Received: 27 April 2022

| Accepted: 31 May 2022

DOI: 10.1111/iej.13783

REVIEW ARTICLE

Present status and future directions: Surgical endodontics

Frank C. Setzer | Samuel I. Kratchman

Department of Endodontics, School Abstract

of Dental Medicine, University
Endodontic surgery encompasses several procedures for the treatment of teeth with
of Pennsylvania, Philadelphia,
Pennsylvania, USA a history of failed root canal treatment, such as root-­end surgery, crown and root
resections, surgical perforation repair and intentional replantation. Endodontic mi-
Correspondence
Frank C. Setzer, Department of
crosurgery is the evolution of the traditional apicoectomy techniques and incorpo-
Endodontics, School of Dental rates high magnification, ultrasonic root-­end preparation and root-­end filling with
Medicine, University of Pennsylvania, biocompatible filling materials. Modern endodontic surgery uses the dental operat-
240 S 40th Street, Philadelphia, PA,
19104, USA. ing microscope, incorporates cone-­beam computed tomography (CBCT) for preop-
Email: fsetzer@upenn.edu erative diagnosis and treatment planning, and has adopted piezoelectric approaches
to osteotomy and root manipulation. Crown and root resection techniques have ben-
efitted from the same technological advances. This review focuses on the current
state of root-­end surgery by comparing the techniques and materials applied during
endodontic microsurgery to the most widely used earlier methods and materials. The
most recent additions to the clinical protocol and technical improvements are dis-
cussed, and an outlook on future directions is given. Whilst nonsurgical retreatment
remains the first choice to address most cases with a history of endodontic failure,
modern endodontic microsurgery has become a predictable and minimally invasive
alternative for the retention of natural teeth.

KEYWORDS
crown resection, endodontic microsurgery, endodontic surgery, management of endodontic
problems, root resection

I N T RO DU CT ION After these early approaches, there have been many

changes and iterations to endodontic surgical tech-
Endodontic surgery has a long-­standing tradition as a den- niques, with varying acceptance and success. For many
tal procedure. Various clinicians introduced concepts of years, surgical burs were used for osteotomy and root-­
apical surgery in the late 19th and early 20th centuries. end resection, and amalgam as a root-­end filling ma-
The intention was to remove necrotic portions of the apex terial (Castenfelt, 1939; Dorn & Gartner, 1991; Harty
(Beal, 1908; Brophy, 1880; Farrar, 1884) and to excise dis- et al., 1970; Oginni & Olusile, 2002). With advances in
eased periapical tissues. These approaches, however, did initial root canal treatment and nonsurgical retreatment,
not take into account the presence of intra-­radicular in- the utilization of endodontic surgery was called into
fection (Regan et al., 2005). Root-­end resection gained fur- question due to several clinical studies with very low out-
ther attention after publications by Partsch (1896, 1898, come rates (Allen et al., 1989; Frank et al., 1992). These
1899) and Faulhaber and Neumann (1912). low outcome rates were likely related to the continued

© 2022 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Int Endod J. 2022;00:1–39.  wileyonlinelibrary.com/journal/iej | 1

2 |    SURGICAL ENDODONTICS

presence of intra-­and/or extra-­radicular infection after A variety of tooth-­related factors may necessitate sur-
surgical intervention. gical retreatment, including complicated root canal anat-
Modern iterations of endodontic surgery have largely omy, the pathophysiology of the apical pathosis, severe
addressed these issues by applying improved methods to alterations of the root canal anatomy during endodontic
the procedure, including high magnification and illumina- treatments, root filling materials, build-­ups or posts im-
tion using surgical operating microscopes or endoscopes, possible to retreat or at unreasonably high risks, as well as
ultrasonic root-­end preparation and root-­end filling with perforations, resorptions or root fractures.
calcium silicate cement (Kim & Kratchman, 2006). This Natural anatomical challenges leading to a decision
review will: for surgical retreatment may include immature root de-
velopment (>1.5 mm in apical diameter), extreme (>30°)
• contrast the present status of endodontic surgery in the or s-­shaped root curvatures, root canal bifurcations in
form of endodontic microsurgery to more common ear- the middle or apical third, overly long roots (>25 mm)
lier applications, or severe calcifications (Karabucak & Setzer, 2007).
• give an overview of some of the procedures included Changes to the original root canal system anatomy that
within the spectrum of endodontic surgery, including may be difficult to overcome consist of ledges, transpor-
root resection or amputation, crown resection (hemi- tations, perforations, internal and external resorptions,
section, trisection and premolarization or bicuspidiza- or separated instruments, which may result in residual
tion) and microorganisms in proximity to the apical constriction
• highlight the most recent additions and technical im- (Walton & Ardjmand, 1992) or apical foramen (Siqueira
provements in endodontic surgery. & Lopes, 2001) due to inadequate biomechanical disinfec-
tion (Gorni & Gagliani, 2004; Figure 1).
Whilst some of these challenges only become apparent
Indications during actual nonsurgical retreatment, some may be pre-
dictable during the treatment planning phase. If the orig-
Nonsurgical or surgical retreatment is an interven- inal root canal anatomy cannot be successfully explored
tion to treat persistent or recurrent apical periodonti- and submitted to biomechanical instrumentation in cases
tis. Nonsurgical retreatment is considered the option with the presence of apical periodontitis, the success rate
of choice in case of an insufficient primary root canal of nonsurgical retreatment dropped as low as 40% (Gorni
treatment and unidentified canals, or if a new defini- & Gagliani, 2004). In this context, it must also be stressed
tive restoration is planned. The majority of periapical that persistent or recurrent apical periodontitis is main-
lesions, including abscesses, cysts (Nair et al., 1996) and tained by a microbiological spectrum posing greater chal-
granulomas (Bergenholtz et al., 1979; Sjögren et al., 1990; lenges to antimicrobial strategies.
Strindberg, 1956), should respond favourably to adequate Previous root fillings with hard pastes or silver
nonsurgical retreatment. Surgical retreatment is indi- points may not be completely removable by nonsurgical
cated when nonsurgical retreatment attempts have failed means. Resorcinol–­formaldehyde pastes (‘Russian Red’;
or are deemed to be unfeasible. Prior to choosing surgical Albrecht, 1915) may be impossible to remove from the
retreatment, the aetiology of a persistent pathosis must root canal system, requiring a surgical approach. In ad-
be thoroughly evaluated (Karabucak & Setzer, 2007). dition, the orthograde retrievability of calcium silicate-­
Asymptomatic periapical lesions should be monitored at based sealers or putty materials is subject to debate. The
appropriate follow-­up appointments to allow sufficient decision to remove an instrument fragment from a root
time for healing. canal by nonsurgical versus surgical means depends on

(a) (b)

F I G U R E 1 Examples of situations
challenging to overcome by nonsurgical
retreatment. (a) Apical transportation
in the mesial root and (b) mid-­root
perforation with fractured instrument
fragment. Dr Samuel Kratchman, Exton,
PA, USA [SK].
SETZER and KRATCHMAN    | 3

(a) (b) (c)

(d) (e) (f)

F I G U R E 2 Surgical removal of a fractured nickel–­titanium rotary instrument fragment in the mesial root of a mandibular right first
molar. (a) Radiograph depicting an instrument fragment in the apical third of the mesial root beyond the canal curvature (arrow), the presence
of an apical radiolucency; (b) resected mesial root surface, portion of instrument fragment in mesiolingual canal (arrow), canal isthmus and
periodontal ligament stained with methylene blue; (c) removed instrument fragment, resected root tip; (d) root-­end cavity, isthmus space
prepared (micro-­mirror view); and (e) root-­end filling with bioceramic root repair material (RRM; Brasseler, Savannah, GA, USA), postoperative
radiograph confirming the instrument fragment removed and the root-­end filling in situ. Courtesy Dr Michael O'Donnell, Tampa, FL, USA.

the presence or absence of apical periodontitis, the lo- (a) (b)

cation of the fragment in the coronal, middle or apical
third, and the type of instrument, for example a stainless
steel hand versus a nickel–­titanium rotary file (Figure 2).
The expected loss of hard tissue structure must be jus-
tifiable to initiate nonsurgical retreatment (Setzer &
Karabucak, 2018). At or beyond a canal curvature, su-
perelastic nickel–­ titanium instruments may wedge
towards the outer canal curvature, which may render re-
moval attempts very difficult or impossible (Parashos &
Messer, 2006), favouring surgery as a less invasive option
(Karabucak & Setzer, 2007). Cast post and core build-­ups, F I G U R E 3 Indication for endodontic surgery Overly
crowns or long metal posts may necessitate the disassem- long, screw-­type posts pose a potential risk of root fracture by
bly of an existing coronal restoration, which could come nonsurgical retreatment. (a) Maxillary central incisors with
at an elevated risk of hard tissue loss, root fracture or large posts filling more than half of the root and unfilled canal
perforation, favouring a surgical approach (Karabucak & spaces beyond the posts; and (b) postoperative radiograph after
Setzer, 2007; Figure 3). endodontic microsurgery, root-­end instrumentation and root filling
Resorption repairs in the coronal aspect of a with a bioceramic sealer (BC; Brasseler) and RRM. Dr Frank Setzer,
tooth likely warrant a nonsurgical approach (Meister Philadelphia, PA, USA [FS].
et al., 1979; Nicholls, 1962; Pitt Ford et al., 1995a,
1995b; Pitt Ford, Torabinejad, et al., 1995; Setzer & Histologically, periapical lesions are overwhelmingly
Karabucak, 2018), whereas a more apical position will inflammatory pathoses. According to Nair et al. (1996),
favour endodontic surgery (Karabucak & Setzer, 2007), 50% of lesions were granulomas, 35% were periapical ab-
in particular, if a resorptive defect did not arrest after scesses, and 15% were pocket or true cysts. Pocket cysts
nonsurgical treatment (Figure 4). Vertical root fractures have a direct connection to the infected root canal sys-
can be assessed by exploratory procedures (Figure 5). tem, whereas true cysts are independent of the root (Nair
Root amputation of a fractured root may save a multi-­ et al., 1996, Nair, 2006; Figure 7). Primary endodontic
rooted tooth (Figure 6). treatment or nonsurgical retreatment may not allow for
4 |    SURGICAL ENDODONTICS

(a) (b) (c)

(d) (e) (f)

F I G U R E 4 Surgical resorption repair. (a) Maxillary left central incisor with cervical resorptive defect apical to the cementoenamel
junction (arrow); (b) cone-­beam computed tomogram (CBCT) rendering of palatal surfaces of the maxillary incisors, confirming palatal
cervical resorption (arrow); (c) palatal cavity preparation after surgical envelope flap to reach the apical extent of the resorption at bone level
(note the gutta-­percha filling in the root canal where treatment was performed in anticipation of a canal exposure during resorption repair);
(d) resorptive defect repaired with Geristore (Den-­Mat); (e) postoperative radiograph; and (f) 2-­year follow-­up radiograph [SK].

(a) (b)

F I G U R E 5 Assessment prior to exploratory surgery. (a) Preoperative radiograph, 4 months after root-­end surgery, sinus tract was traced
with gutta-­percha (arrow); (b) exploratory procedure confirmed vertical root fracture (arrow), stained with methylene blue [SK].

the healing of true cysts (Nair et al., 1996), necessitating The dentist's decision-­making has to include a detailed
endodontic surgery. Foreign body reactions, by gutta-­ medical and dental history and clinical examination. A
percha and other filling or sealer materials, paper point patient has to be informed about all appropriate treat-
remnants and cholesterol clefts were identified within ment alternatives and their prognoses and risks. Surgical
cystic lesions (Nair, 1998, 2006; Nair et al., 1993). Lastly, procedures exhibit potential risks of damage to adjacent
extra-­radicular infections may be found as biofilms on an anatomical structures, postoperative swelling, discomfort
external root surface (Tronstad et al., 1990) or in the form or impaired wound healing. A patient must be allowed to
of Actinomyces and Propionibacterium colonies within choose based on their understanding of the advantages
asymptomatic lesions (Nair, 1987; Ricucci & Siqueira and disadvantages of proposed alternatives, the value
Jr, 2008; Sjögren et al., 1988; Sunde et al., 2003), and may their tooth presents to them, costs and their ability to un-
necessitate endodontic surgery (Figure 8). dergo specific dental procedures (Kvist, 2001).
SETZER and KRATCHMAN    | 5

(a) (b)

(c) (d)

F I G U R E 6 Root amputation of the mesial root of a mandibular left first molar. (a) Preoperative radiograph with large periradicular
lesion circumferentially around the mesial root; (b) postoperative radiograph after root amputation of the mesial root following clinical
confirmation of a vertical root fracture; (c) 4-­month follow-­up radiograph, the distal root demonstrates normal apical tissues; and (d)
11-­month follow-­up; the mesial extraction socket shows bony regeneration; the patient has received a new crown. Note the mesial extension
of the crown due to the remaining coronal tooth structure [SK].

(a) (b)

F I G U R E 7 Histologic appearance of pocket cysts versus true cysts. (a) Pocket cyst, note the cystic lumen connecting to the root canal
system; and (b) true cyst, note independent apical foramen with the root canal and independent cystic lumen. Arrows indicate epithelial
lining. RC, root canal; D, dentine; EP, epithelium; and LU, lumen. Modified from Ramachandran Nair et al. (1996).

Contraindications contraindicate the use of vasoconstrictors with the local

anaesthesia, severely limiting haemostasis during surgery.
Endodontic surgery can be contraindicated or compro- Lastly, teeth with deficient definitive restorations, a mini-
mised in situations where the close proximity of sensitive mal or questionable crown-­to-­root ratio, advanced peri-
anatomical structures may lead to transient or irreparable odontal disease or increased mobility may not be suitable
damage during a surgical procedure. These structures may for a surgical approach due to a less favourable prognosis.
include the nasal or sinus cavities (Figure 9), the mental and
infra-­alveolar nerves (Figure 10) or the palatal neurovascu-
lar bundle (Figure 11). Targeted surgical approaches dis- PRESENT STATUS —­E NDODONTIC
cussed in this review may provide an appropriate solution. MICROSURGERY
Systemic diseases such as congenital bleeding disorders
may prohibit a surgical approach. A history of intrave- Treatment planning
nous bisphosphonate therapy may pose a highly elevated
risk of bisphosphonate-­related osteonecrosis of the jaws The clinician has to ensure to review a patient's medi-
(Setzer & Karabucak, 2018). Some cardiovascular diseases cal and dental history and perform a proper clinical and
6 |    SURGICAL ENDODONTICS

(a) (b) (c)

(d) (e) (f)

F I G U R E 8 Extra-­radicular infection with actinomycosis. (a) Preoperative radiograph with periradicular lesion present around
mandibular right central and lateral incisors after failed primary root canal treatment and failed nonsurgical retreatment; (b) intraoperative
situation after root-­end filling of lateral incisor with RRM (micro-­mirror view); (c) postoperative radiograph with root-­end fillings in situ;
(d) histology-­confirmed actinomycosis; (e) 7-­month follow-­up radiograph, note decrease in lesion size; and (f) 2-­year follow-­up radiograph,
healthy apical tissues; the patient was asymptomatic. Courtesy Dr Meetu Kohli, Philadelphia, PA, USA.

(a) (b)

F I G U R E 9 Maxillary sinus perforation. (a) The sinus perforation (arrow) occurred after root resection of maxillary left second premolar
and removal of granulation tissue, (b) placement of a collagen-­based bone augmentation material (Foundation®; J. Morita USA Inc.) to close
the perforation site, prior to the initiation of bleeding. Courtesy Dr Karla Sermeno De Castillo, Austin, TX, USA.

radiographic examination prior to arriving at a clinical the surrounding tissues to avoid iatrogenic damages dur-
diagnosis. A patient's chief complaint needs to be ad- ing the surgical intervention. However, despite the fact
dressed. If a decision for endodontic surgery has been that CBCT has now been widely adopted in Endodontics
made, a three-­dimensional radiograph should be taken (Scarfe et al., 2009; Setzer et al., 2017), the relatively high
for both diagnostic and medico-­legal purposes. For the radiation exposure compared to periapical radiographs
majority of dental procedures, including endodontic sur- has to be considered and the ALARA principle followed
gery, a limited field-­of-­view (FOV) cone-­beam computed at all times. CBCT allows for the precise evaluation of
tomogram (CBCT) is sufficient to evaluate not only the the size and location of a periradicular lesion, the bone
tooth or teeth undergoing the surgical operation but also thickness over the pathosis, and the proximity to adjacent
SETZER and KRATCHMAN    | 7

(a) (b)

(c) (d)

F I G U R E 1 0 Proximity of the mental foramen to a periradicular lesion and the root tip (a) preoperative radiograph depicting the
overlapping of the lesion (red) and the mental foramen (green) on a mandibular left second premolar; (b) clinical situation after flap
reflection; periodontal probe indicates the approximate location of the root tip. Note the round, stratified appearance of the inflammatory
tissues of the lesion. The mental nerve is embedded in the mucoperiosteal flap and connects to the periapical lesion; (c) removal of some
inflammatory tissues—­arrow indicates mental foramen and mental nerve; (d) root tip visible—­the nerve bundle continues into the apical
portion of the inflammatory lesion (arrow) [SK].

(a) (b)

F I G U R E 1 1 Palatal neurovascular bundle. (a) Flap reflection for root-­end surgery of the palatal root of the maxillary left first molar—­
arrow indicates the neurovascular bundle embedded in the flap, originating from the greater palatine foramen in proximity to the palatal
root tip of the second molar; and (b) surgical site after root-­end resection and filling (left arrow); note the neurovascular bundle protected by
a retractor (right arrow) [FS].

anatomical structures such as the infra-­alveolar and men- and the greater palatine artery canals (Figure 14), making
tal nerve, sinus and nasal cavities and neighbouring roots CBCT an important tool for guided microsurgical tech-
(Frank et al., 1996; Setzer et al., 2017). Whilst there are niques discussed further below.
still impediments in the detection of vertical root fractures
due to limitations in CBCT resolution and beam harden-
ing effects of root filling materials or other radiographic Armamentarium
artefacts, characteristic patterns of bone loss in the form of
an abrupt, narrow vertical defect may indirectly indicate A variety of kits are available for modern endodontic
their presence (Chang et al., 2016; Menezes et al., 2016; surgery and typically consist of miniaturized versions of
Figure 12). To treatment plan endodontic surgery, CBCT standard surgical instruments, often specifically designed
allows accurate measurements of relevant distances, to work under high magnification with a dental operat-
including the buccal bone surface to the root tip or the ing microscope or endoscope. Standard instrument sets
length of a root (Bornstein et al., 2011; Figure 13). In con- should include hand instruments, such as a dental mirror,
trast to two-­dimensional radiographs, CBCT also allows a periodontal probe, an endodontic explorer and micro-­
for the detection of the posterior superior alveolar nerve explorer, a surgical blade holder, and tissue elevators for
8 |    SURGICAL ENDODONTICS

F I G U R E 1 2 CBCT evaluation of a
mandibular left first molar with suspicion
of vertical root fracture in the distal root.
Note the periodontal bone loss in the
coronal view and the J-­shaped lesion
in the sagittal view, both indicative of
a vertical root fracture. The axial view
depicts the extension of the lesion
between the roots of the molar and allows
the assessment of the thickness of the
cortical plate [SK].

(a) (b) F I G U R E 1 3 Treatment planning

with CBCT. (a) Preoperative periapical
radiograph of a mandibular left first
molar with a radix entomolaris (third,
distolingual root); (b) sagittal view,
showing periapical lesions on the
mesial and distobuccal roots, allowing
for measurement of the root length; (c)
coronal view—­distance measured from
distolingual root apex to lingual cortical
(c) (d) plate; and (d) axial view, assessment of the
depth needed to cut the distolingual root
(arrow) in its entirety [SK].

incision and flap elevation; periodontal curettes, surgical as anaesthesia syringe, college pliers, air–­water syringe
curettes, and micro-­endodontic curettes for the removal and a micro-­ irrigator (Figures 16 and 17). Disposable
of pathologic tissues; micro-­mirrors and handle for in- items include anaesthetic solution, surgical blades, bone-­
spection; and carriers and pluggers for root-­end filling cutting burs, gauze and cotton pellets, haemostatic agents,
(Figure 15). In addition to hand instruments, the follow- dyes, saline, root-­end filling and perforation repair materi-
ing armamentarium is needed: a 45° surgical handpiece als, bone grafting and membrane materials, and sutures.
and burs for osteotomy and root resection; tissue retrac- In addition, piezoelectric devices for specific osteotomy
tors; an ultrasonic unit with corresponding tips for root-­ techniques, such as the creation of protective grooves or a
end preparation; a microsurgical tissue forceps; needle bone window, are helpful and have recently increased in
holder and scissors; and miscellaneous instruments such usage (Figure 18).
SETZER and KRATCHMAN    | 9

(a) (b)

F I G U R E 1 4 Detection of the posterior superior alveolar nerve and the greater palatine artery canals. (a) Posterior superior alveolar
nerve canal depicted on axial, coronal and sagittal views (arrows); and (b) greater palatine artery canal visible in axial and coronal views
(arrows) [SK].

F I G U R E 1 5 Surgical armamentarium. Top row, left to right: plastic soft tissue retractor for flap elevation and suturing, micro-­mirrors,
endodontic finger ruler and epinephrine pellets. Bottom row, left to right: mouth mirror, periodontal probe, micro-­explorer (EndoBlack
surgical instruments; Brasseler), elevators, soft tissue curettes and spoon excavators, forceps, syringe with anaesthetic, methylene blue
(blue), ferric sulphate (brown) and micro-­applicators.

Patient positioning microscope provides high magnification, coaxial illumi-

nation and ergonomic seating for the clinician (Kim &
Endodontic microsurgery is applicable to the majority of Kratchman, 2006; Setzer et al., 2012). The direct vision
teeth in both jaws, with the exception of second mandibu- provided by the microscope allows the operator to exam-
lar molars and wisdom teeth. A key aspect of the proce- ine and treat both pathologic tissues and root structure
dure is the positioning of the patient, the clinician and the more precisely and thus minimally invasive. As with in-
assistant (Jouanny & Safi, 2014; Kratchman & Kim, 2017) creasing magnification, the focal depth becomes smaller,
for both the comfort of the patient and the ability of the and correct patient positioning becomes important not
surgical team to execute the procedure to the best of only for the proper execution but also for the efficiency
their ability. For endodontic microsurgery, the operating of the procedure. For each step of the procedure, the
10 |    SURGICAL ENDODONTICS

F I G U R E 1 6 Surgical armamentarium. Top row, left to right: glass slab with RRM, 6-­0 monofilament sutures. Bottom row, left to right:
plastic instruments and condensers, scissors, surgical tissue forceps, micro-­needle holder, micro-­scissors and soft tissue retractors.

elevation, osteotomy and root resection, a patient remains

in a horizontal position just as the long axis of the tooth
undergoing surgery. When the root resection is completed
and verified, the patient has to be readied for ultrasonic
root-­end preparation by ensuring the direct vision of the
resected root surface to avoid misalignment of the ultra-
sonic tip and limit the osteotomy to a reasonable size. This
is achieved by uprighting the chair when working on max-
illary teeth (Figure 20) and further reclining for working
on mandibular teeth (Figure 21). The original position can
resume after the root-­end filling is completed.
F I G U R E 1 7 Chairside attachments: air–­water syringe,
ultrasonic handpiece and 45° surgical handpiece with Lindemann
bur. Anaesthesia

Local anaesthesia in endodontic surgery is used for

both profound analgesia and haemostasis (Kim &
Rethnam, 1997). A resected root surface must be examined
under high magnification to identify problems that may
have led to the failure of the previous endodontic procedure.
Haemostasis provided by a local anaesthetic is achieved
by the addition of a vasoconstrictor, ideally 1:50 000 epi-
nephrine (with 1:80 000 epinephrine as an alternative if a
higher concentration is unavailable; Buckley et al., 1984;
Gutmann, 1993; Kim et al., 2001). A higher concentration
of the vasoconstrictor more effectively reduces bleeding if
it is injected in the submucosa (Gutmann, 1993; Jastak &
F I G U R E 1 8 Piezotome with piezoelectric handpiece Yagiela, 1983; Witherspoon & Gutmann, 1996). Effects of
(Woodpecker US-­II LED Piezo Surgical Unit; Woodpecker Medical higher epinephrine concentrations on the cardiovascular
Instruments Co.). system were raised as a concern (Jastak & Yagiela, 1983;
Troullos et al., 1987), as the plasma level of epinephrine
appropriate magnification level, low, mid and high, has to is elevated when a high dose is administered. Epinephrine
be chosen dependent on whether an overview of an area binds to adrenergic receptors located on the vascular
with several teeth, a single tooth, or specific details must smooth muscles. The predominant receptors in the oral
be in the field of vision (Figure 19). During soft tissue tissues are α-­receptors. Thus, epinephrine predominant
SETZER and KRATCHMAN    | 11

F I G U R E 1 9 Comparison of magnification ranges achievable with loupes versus a dental operating microscope. Procedural steps in
endodontic microsurgery are carried out at low, mid and high magnification.

F I G U R E 2 0 Patient positioning for direct observation of the F I G U R E 2 1 Patient positioning for direct observation of the
resected root surface in the maxilla. The patient's chin is tilted resected root surface in the mandible. The patient's head is inclined
downwards; the microscope is tilted away from the clinician. backwards, the chin is tilted upwards, and the microscope is tilted
Modified from Kratchman and Kim (2017). towards the clinician. Modified from Kratchman and Kim (2017).

effect in the oral mucosa, submucosa and periodontium the surgical haemostasis in the operating field. Unless a di-
is vasoconstriction (Kim & Kratchman, 2006). Therefore, rect injection into a blood vessel takes place, potential car-
the application of local anaesthetics containing epineph- diovascular effects should be short-­lived and minimal and
rine 1:50 000 should be a constraint to injections 1–­2 teeth well-­tolerated by the majority of patients. For patients with
mesial and distal from the tooth receiving surgery into the a history of cardiovascular disorders or surgery, higher
buccal or palatal submucosa using an aspirating syringe. epinephrine concentrations may be contraindicated, and a
Higher epinephrine concentrations are unnecessary for an consultation with the patient's physician will be necessary
infra-­alveolar nerve block since there is no contribution to (Besner, 1972; Knoll-­Kohler et al., 1989; Yagiela, 1995).
12 |    SURGICAL ENDODONTICS

Flap designs—­soft tissue management to other flap designs because of a compromised blood sup-
ply to the flap (Kramper et al., 1984). Similarly, a single
With the exception of palatal roots of maxillary molars, vertical incision above the root, with lateral retraction to
surgical access for endodontic microsurgery is generally expose bone over the apex (Buckley, 1911; Weaver, 1949),
from the buccal, which presents with three tissue types, is not considered a viable option nowadays due to reduced
alveolar mucosa, the attached gingiva and the marginal access to larger lesions and an increased risk of postop-
gingiva. The alveolar mucosa is a thin, nonkeratinized erative infection, as the closed sutures will be directly on
mucosal layer loosely attached to the underlying bone. top of the osteotomy site. Contemporarily, the two most
The attached gingiva is the portion of gingiva extending widely used flap designs are the intra-­sulcular and sub-
from the base of the gingival crevice to the mucogingival marginal incisions.
junction, firmly connected to the underlying bone and The intra-­sulcular incision is a long-­established flap
cementum and therefore immovable. The marginal gin- design (Hofer, 1935). It is a full-­thickness flap that aims
giva is the crest of the free gingiva surrounding the tooth, at keeping the blood supply intact to allow for primary
forming the soft tissue portion of the gingival sulcus. Any wound healing (Gutmann & Harrison, 1991; Figure 22).
surgical manipulation must be carefully undertaken to Variations are a triangular flap with a singular, and a
minimize any potential scarring. Proper flap design and rectangular flap with two vertical incisions. For many
tissue elevation must allow for appropriate surgical access situations where a single tooth is undergoing surgery, a
to the underlining bone, root structure and pathosis and triangular design allows for sufficient access. A rectan-
facilitate uncomplicated and scar-­free soft tissue healing gular design may be needed to address a large periapi-
(Mitsis, 1970). Many flap designs have been introduced for cal lesion or in case multiple teeth require intervention.
endodontic surgery over the years (Velvart & Peters, 2005; Intra-­sulcular flap designs demonstrated excellent reat-
Velvart et al., 2005a, 2005b; von Arx & Salvi, 2008). The tachment, and minimal postoperative pain and swell-
semilunar flap, involving a curved incision entirely situ- ing, as postoperative infection of the blood coagulum in
ated in the mucosa (Brock, 1961), is now considered obso- the bony crypt is unlikely (Gutmann & Harrison, 1991).
lete due to its limited access to larger periradicular defects, Disadvantages may include moderate gingival recession,
challenges with reapproximation, delayed secondary which may be of concern in an aesthetic area, such as the
healing, increased postoperative swelling and pain, flap maxillary anterior region, or when artificial crown mar-
shrinkage, and the potential for more scarring compared gins are present (Kramper et al., 1984). Dental papilla

(a) (b)

F I G U R E 2 2 Intra-­sulcular incision. (a) Schematic diagram, triangular flap design for surgical access to a mandibular first molar with a
vertical release of two teeth mesial at the first premolar to avoid iatrogenic damage to the mental nerve (from Maggiore & Setzer, 2017); and
(b) clinical representation [FS].

(a) (b) (c)

F I G U R E 2 3 Papilla-­base flap. (a) Preoperative view in the anterior maxilla, note attached gingiva versus buccal mucosa; (b) surgical
incision dissecting the papilla base as described in the narrative; (c) full-­thickness flap elevated, note the three papillae remaining intact
below the interproximal contacts and the large apical defect [FS].
SETZER and KRATCHMAN    | 13

(a) (b)

F I G U R E 2 4 Submarginal incision. (a) Schematic diagram, triangular flap design for surgical access to a maxillary lateral incisor with
a scalloped horizontal incision within the attached gingiva and a vertical release one tooth mesial at the central incisor, parallel to the
frenulum (from Maggiore & Setzer, 2017); and (b) clinical representation [FS].

damage may occur (Grung, 1973; Velvart et al., 2004), par-

ticularly when the soft tissues are poorly keratinized, the
papilla is very thin, or by iatrogenic errors. Preservation of
the papilla with this flap design is most predictable, when
the vertical incision joins the horizontal incision lateral to
the papilla at the cervical margin at a 90° angle, which
provides the best blood supply. The intra-­sulcular incision
may not be well suited for patients with a high smile line
or a thin-­scalloped periodontal biotype. The papilla base
incision is a variation of the intra-­sulcular incision that
aims at avoiding papilla recession by placing the intra-­ F I G U R E 2 5 Scar tissue formation due to misplacement of the
sulcular component of the incision only in the buccal–­ horizontal incision at the border of attached gingiva and mucosa
cervical aspect of the tooth, but leaving the papilla intact [documented by SK].
by continuing the incision line through the base of the
papilla without detaching it with the flap (Velvart, 2002; Osteotomy
Figure 23). Significantly less recession of the papilla may
occur if this incision is used (Velvart et al., 2004). Periradicular lesions may be fully contained inside the
The submarginal incision is a flap design, where, in bone or may have already penetrated a cortical plate. In
contrast to the intra-­sulcular incision, the free gingiva sur- the latter situation, simple curettage of the inflamma-
rounding the teeth will not be detached (Figure 24). This flap tory tissues may be enough to expose and identify a root
design was introduced over a century ago (Neumann, 1926) tip. If a root tip is still covered by bone, the practitioner
and further propagated by Ochsenbein-­ Luebke (Lubow will have to use the information gained from pre-­surgical
et al., 1984). The key element of the design is a horizon- treatment planning, including clinical observation and
tal, submarginal incision in the middle of the attached the preoperative measurements derived from periapical
gingiva following the contour of the cervical margin. Both radiographs or a CBCT. The operator must be conscious
rectangular and triangular variations of the flap are avail- of the proximity of the surgical field to root apices of ad-
able to the operator, with the same indications as outlined jacent teeth, the infra-­alveolar nerve, the mental foramen,
above. This flap design is ideally indicated in situations the nasal cavity or the maxillary sinuses (Jang et al., 2017;
where the attached gingiva is wider, to leave gingival tis- Kuzmanovic et al., 2003; Oberli et al., 2007). Endodontic
sues undisturbed, such as in the maxillary anterior region, microsurgery is a minimally invasive procedure. An oste-
in the presence of artificial crown margins, or other aes- otomy site should be kept as small as possible whilst al-
thetically challenging situations (Grung, 1973). Situations lowing for the removal of inflammatory tissues, adequate
where surgical access is limited, or a large periradicular root resection, an inspection of the resected root surface,
lesion, particularly in the coronal–­apical direction, is pres- root-­end preparation and root-­end filling. Boyne et al.
ent, may be contraindications for this flap design. Whilst (1969) demonstrated differences in the healing of osseous
the submarginal incision provides good preadaptation and defects in the anterior region depending on the size of the
wound healing most of the time, postoperative scarring has lesion. Lesions 5–­8 mm in diameter healed with complete
been noted in circumstances where soft tissues had teared bone regeneration, whilst defects with a 9–­12 mm cross
(Kramper et al., 1984) or the horizontal incision did not stay section demonstrated herniations with fibrous tissue
within the attached gingiva, but had been placed directly at (Figure 26). Similarly, Hjorting-­Hansen (1970) provided
the delineation of attached gingiva and mucosa (Figure 25). evidence that cavity spaces up to 5 mm could result in
14 |    SURGICAL ENDODONTICS

(a) (b) (c) (d)

F I G U R E 2 6 Healing with probable scar tissue formation of a case with a large defect. (a) Preoperative periapical radiograph, a
radiolucency is apparent distal to the maxillary right lateral incisor; (b, c) defect size measurements taken in coronal and sagittal views; (d)
9-­month follow-­up, incomplete healing. Courtesy Dr Roy Nesari, San Francisco, CA, USA.

apices of the first molar or the first premolar. The distance

of the mental foramen to the closest root ranged from 0.3
to 9.8 mm (Aminoshariae et al., 2014; Figure 27). In more
rare instances, its location was shown to be at the same
vertical height or coronal to the apices of adjacent teeth or
to present with a secondary foramen (Abella et al., 2014;
Oberli et al., 2007). The mandibular canal is located infe-
rior and lingual to the root apices of mandibular molars.
The canal is usually at a safe distance from the root tips
of the first molars. However, due to its close proximity
to apices of second molars, together with their posterior
location and the thickness of the bone in the area of the
ramus, it typically prohibits conventional microsurgical
approaches to these teeth.
Protection of the mental foramen during mandibular
posterior surgery mandates a specific protocol, including
an intra-­sulcular incision for a better overview, a vertical
incision mesial of the first premolar for surgical proce-
F I G U R E 2 7 Mental foramen location in relation to the
dures of both second premolar and first molar, and the
mandibular first and second premolars and the first molar (from
placement of a bony groove for safe anchorage of the
Mendez-­Montalvo et al., 2017).
retractor. This bony groove should not exceed 1.5 mm in
width and should only be cut deep enough to provide safe
complete bone regeneration independent of the anatomi- support for a surgical retractor. When correctly applied
cal site. Radiographic observation also demonstrated a di- by either a surgical bur or a piezoelectric device, slippage
rect relationship between osteotomy size and the speed of of a retractor or accidental trauma with a surgical instru-
healing—­the smaller the osteotomy, the faster the healing ment is less likely, and the risks of transient or permanent
(Rubinstein & Kim, 1999). An atraumatic minimized hard trauma to the mental nerve are greatly reduced (Abella
tissue approach must be supported by careful handling of et al., 2014; Figure 28).
the surrounding soft tissues and protection of sensitive ad- The maxillary sinus may not be only close to the sur-
jacent structures. gical site, but it may also be exposed if a periapical lesion
The mental and inferior alveolar neurovascular bun- reaches or perforates the membrane. An opening to the
dles are frequently encountered in the proximity of a oral cavity may occur by excision of the inflammatory tis-
surgical site. Radiographic assessment and CBCT imag- sues (Hauman et al., 2002). Precaution needs to be taken
ing, together with careful treatment planning, are essen- if a sinus perforation is likely to happen or if it has al-
tial for endodontic surgery in the mandibular molar and ready occurred. No tissue remnants or foreign body mate-
premolar area (Imada et al., 2014; Moiseiwitsch, 1995; rials must be displaced into the sinus cavity. The manner
Shibli et al., 2010; von Arx et al., 2013). In a majority of of how to resect the root tip was debated, in particular
situations, the mental foramen is located near the apex of if it is advisable to carefully reduce a root tip (Lemon
the second mandibular premolar and less often near the et al., 1993) rather than to cut it whilst securing the apex
SETZER and KRATCHMAN    | 15

(a) (b)

F I G U R E 2 8 Mental foramen and nerve management. (a) Flap reflection by careful application of backpressure to the periosteal side of
the flap, thereby gently detaching the flap from the bone, avoiding iatrogenic damage to the mental nerve (arrow) and (b) creating a bony
groove using the piezotome for the anchorage of the retractor [FS].

(a) (b) (c)

(d) (e) (f)

F I G U R E 2 9 Protection of the maxillary sinus. (a) Preoperative radiograph with an apical lesion on the distobuccal root of a maxillary
left first molar in immediate sinus proximity (arrow); (b) exposure of distobuccal root (arrow), curettage of granulation tissues; (c) resection
of the intact root tip rather than gradually shaving down the root, to avoid dentinal shavings entering the sinus; (d) root-­end filling with
mineral trioxide aggregate (MTA; Dentsply Sirona; arrow); (e) postoperative radiograph; and (f) 1-­year follow-­up radiograph, complete
healing [SK].

(a) (b)

F I G U R E 3 0 Protection of the maxillary sinus with a cotton pellet during the surgical procedure. (a) Granulation tissues were firmly
attached to the sinus membrane, perforation of the sinus has occurred; and (b) placement of a sterile cotton pellet in the sinus opening,
secured by a surgical suture. If the cotton pellet is accidentally dislodged into the sinus, it can be retrieved by gently pulling the suture back
towards the opening and grabbing the cotton pellet carefully with small forceps [SK].
16 |    SURGICAL ENDODONTICS

(Guess & Kratchman, 2017). On the one hand, the opera- molar may include the neurovascular bundle within the
tor must avoid the displacement of dentinal shavings into flap (Figure 11). However, any posterior attempt on a sec-
the sinus (Figure 29). On the other hand, a root tip might ond molar may involve the foramen with danger to the
be at risk of displacement as a whole. A sterile cotton pel- bundle and may greatly increase the risk of severe hae-
let secured by a suture can be placed temporarily into the morrhage or nerve injury. The vertical releasing incision
sinus opening to block any shavings or foreign body ma- for a palatal flap should be placed between the canine
terials from entering the sinus (Kim & Kratchman, 2006; and the first premolar (Gutmann & Harrison, 1985, 1991).
Figure 30). Watzek et al. (1997) demonstrated that the Transantral approaches to the palatal roots have been de-
outcome of endodontic surgery would not be compro- scribed (Altonen, 1975; Walton & Wallace, 1996) but are
mised by a sinus opening itself, as the repositioned flap nowadays limited to root fusions of distobuccal and pal-
will provide protection after the surgical procedure. atal roots to allow for adequate root-­end preparation and
Larger sinus openings may require a bone grafting ma- root-­end filling (Figure 31). For individual palatal roots,
terial such as collagen or a membrane covering the buc- a transantral approach may be greatly limited by the dis-
cal defect. Antibiotic coverage may be advised but is not tance from the buccal wall to the palatal apex and may
necessary for all patients. However, a decongestant may pose additional risks of leaving dentinal shavings or for-
prevent any pressure issues from within the sinus to dis- eign body materials in the sinus.
turb wound healing.
The palatine neurovascular bundle may be at risk
during palatal surgery, which is largely limited to first Apical curettage
molars. Maxillary premolars are treated via a buccal ap-
proach. Conventional, nontargeted endodontic micro- The removal of the inflammatory tissues of the apical
surgery from palatal is no option for second molars in periodontitis around the root tip is an integral part of
almost all situations due to the anatomical risks. The root-­end surgery. Limited indications exist for apical
greater palatine foramen is located approximately 3–­4 mm curettage as a self-­sufficient procedure without root re-
anterior to the posterior border of the hard palate, with section or root-­end filling, including exploratory proce-
nerves and blood vessels projecting in an anterior direc- dures for the identification of vertical root fractures or
tion in the submucosa approximately halfway between other situations when a tooth is declared nonrestorable.
the midline of the palate and the gingival margin. Palatal Teeth that undergo a surgical procedure should receive
soft tissue elevation to approach the palatal root of a first treatment that addresses both potential intra-­radicular

(a) (b) (c) (d)

(e) (f) (g)

F I G U R E 3 1 Transantral approach in a maxillary first left molar with a distobuccal/palatal root fusion. (a) Preoperative radiograph,
apical radiolucency on the mesiobuccal root and no indication of proximity to sinus; (b) distobuccal and palatal root fusion, access to the
root will open the sinus, coronal view; (c) root fusion, axial view; (d) measurements to reach the entire root during resection; (e) clinical
picture after root resection, left arrow shows mesial root with first and second mesiobuccal canals resected, and right arrow shows fused root
with isthmus; (f) root fillings in situ; and (g) postoperative radiograph. Courtesy Dr Lindi Orlin, Exton, PA, USA.
SETZER and KRATCHMAN    | 17

and extra-­radicular causes for failure. Therefore, root-­

end resection and root-­end filling must be part of the
procedure to maximize surgical prognosis. Whilst
granulomas or abscesses are expected to heal after the
aetiology of a failed root canal treatment has been ad-
dressed, it cannot be determined during surgery if an
extra-­
radicular infection is present. Thus, the entire
periradicular lesion should be removed (Brock, 1961;
Lin et al., 2010; Nichols, 1965; Rud & Andreasen, 1972)
to include any epithelial remnants that might continue
the proliferation of a cystic lesion or any extra-­radicular
infection. The concept of selective curettage has been
recently introduced as a conservative approach to treat- F I G U R E 3 2 Bevel angle on the distal root of a mandibular
ing large and complicated lesions by removing 50%–­70% left first molar. A shallow bevel angle prevents the opening of
of the soft tissue lesion to avoid iatrogenic damage to more dentinal tubules. Proper patient positioning and microscope
neighbouring structures and successfully demonstrated angulation allow for direct visualization of the resected root
surface (arrow). Note staining with methylene blue and residual
in a case series (Nesari et al., 2020).
epinephrine pellet in osteotomy site of mesial root during resection
and inspection of the distal root [FS].

Root-­end resection

After removal of the inflammatory tissues from the per-

iradicular area, the root tip should be identifiable. In
comparison with the white colour of the bone, which is
soft and bleeds upon scraping, a root has a darker, yel-
lowish colour and is hard (Kim et al., 2001). The root-­end
resection will address intra-­radicular infection that may
be contained in the anatomical complexities of the apex,
including apical ramifications, accessory canals or severe
apical curvatures; iatrogenic mishaps that prevented bio-
mechanical disinfection of the root canal system by means
of nonsurgical retreatment, such as perforations, ledges, F I G U R E 3 3 Comparison of root resection angles. Incomplete
transportations or foreign body materials; apical root root resection at 1 and 2. Note how a lateral canal (red line in
fractures or cracks; or apical resorptions that prevented vertical cross section on the left) translates to a horizontally
an adequate seal during the conventional procedure. The resected canal in 2 (red dot). Complete resection at 3. Modified
root-­end resection will also aid in removing other aetio- from Floratos et al. (2017).
logical factors from the tissues, such as foreign body ma-
terials attached to the tooth or extra-­radicular infection in
the form of a biofilm on the root surface. The resection of An anatomical study identified that the apical 3 mm of
the apex should be performed with a Lindemann bone-­ a root tip contained 98% of apical ramifications and 93%
cutting bur (Figure 17), a fissure bur or a piezoelectric tip of lateral canals, suggesting to use this value as a clini-
to allow for a smooth resection that permits the inspection cal guideline for resection (Kim & Kratchman, 2006).
of the anatomy on the resected root surface, thus allowing Nevertheless, the actual amount of resection may vary
for the identification of potential reasons for the failure of from case to case. The proximity of anatomical structures
the previous treatment. such as the mental nerve may necessitate resection of a
The literature does not present a uniform opinion on longer apical portion of the root to minimize the risk of
how much of the root should be resected. However, there damaging the nerve structure. Cracks or fracture lines
is consensus that resection to the base of the lesion, which must be eliminated completely, if necessary, exceeding
had been advocated earlier (Buckley, 1914), is nowadays the 3-­mm guideline. On the contrary, if there is a limited
regarded as unnecessary (Gutmann & Harrison, 1985, amount of root structure available apical of a post, the
1991). The preservation of as much buccal bone as possi- tooth presents with significant resorptions, or if there is
ble is advised. Gilheany et al. (1994) proposed to resect at a history of previous surgical intervention, the amount of
least 2 mm to minimize bacterial leakage from the canals. resection may be less.
18 |    SURGICAL ENDODONTICS

(a) (b) (c)

F I G U R E 3 4 Application of epinephrine pellet for haemostasis (a) The pellet placed into the osteotomy site will be moistened with
saline solution; (b) waiting period, the pellet (arrow) has been compacted into the bony crypt; and (c) after epinephrine pellet removal and
staining with methylene blue. The resected root surface can now be observed with good haemostasis. Note the outline of the resected root
and the canal lumen filled with debris stained by methylene blue (micro-­mirror view) [FS].

Current recommendations suggest resecting the root

at a shallow 0–­10° bevel rather than a traditional steep
45 ° bevel (Carr, 1994; Kim & Kratchman, 2006; Rud &
Andreasen, 1972; Figure 32). The more perpendicular a re-
section angle is to the long axis of the root, the more apical
root structure may be preserved, the chance of identifying
lingual and accessory canals increases, guarantees a com-
plete root resection, exposes fewer dentinal tubules that
may harbour intra-­radicular infection (Chong et al., 1997;
Gilheany et al., 1994; Gutmann et al., 1994; Tidmarsh &
Arrowsmith, 1989; Figure 33), and allows for an easier
coaxial root-­end preparation with ultrasonic tools. Intra-­
radicular infection may reach the periradicular tissues
F I G U R E 3 5 Precise application of ferric sulphate for
primarily via the apical foramen and accessory and lateral
haemostasis using a micro-­applicator (arrow) (FS).
canals as the major physiological pathways. Whilst bac-
teria are capable of propagating into dentinal tubules, an
intact cementum layer will prevent them from reaching effective haemostat in endodontic surgery (Selden, 1970),
the periodontal tissues. The exposure of microorganisms but it only exhibits a tamponade effect by closing vascu-
to the periradicular tissues via dentinal tubules opened by lar openings in the bone and has no effect on the blood
root resection was discussed as a potential source of in- clotting mechanism. In animal studies, bone wax has
fection of the surrounding tissues. However, a correlation been shown to produce consistent inflammatory reactions
between the presence of bacteria in dentinal tubules and (Ibarrola et al., 1985).
the degree of periradicular inflammation has not been Cotton pellets containing racemic epinephrine hydro-
demonstrated (Rud & Andreasen, 1972). Nevertheless, a chloride (Racellets, Pascal Co.) work both as a mechan-
shallow resection angle will minimize the number of open ical and as a chemical haemostyptic agent. The amount
dentinal tubules after resection. of racemic epinephrine varies with the size of the pellets
and ranges between 0.55 and 1.15 mg on average. The top-
ical use of epinephrine causes immediate local vasocon-
Root-­end inspection striction, with very limited absorption into the systemic
circulation. The pulse rate of patients did not change with
The inspection of the resected root surface is considered the application of racemic epinephrine in the bony crypt
one of the most important steps during endodontic micro- (Besner, 1972). An epinephrine pellet can be placed after
surgery (Kim & Kratchman, 2006). Complete haemostasis all inflammatory tissues are removed. The application of
should be achieved before this procedural step. After rins- backpressure with additional sterile cotton pellets and
ing the osteotomy site with saline, areas that still exhibit the backside of a mirror or college pliers in combination
bleeding may be controlled by using cotton pellets soaked with the epinephrine release has an immediate and pro-
with epinephrine or other haemostatic agents. Ferric sul- found effect on vasoconstriction (Figure 34). It must be
phate and aluminium chloride are likely the most com- ensured that all cotton pellets are removed before wound
monly used today. Bone wax has been described as an closure.
SETZER and KRATCHMAN    | 19

(a) (b) (c)

(d) (e) (f)

F I G U R E 3 6 Inspection of the resected root surface. (a) Application of methylene blue using a micro-­applicator, followed by a saline
rinse; (b) drying of a resected root surface using the Stropko irrigator; (c) resected root surface of a maxillary premolar (mirror view)
with a missed palatal canal (arrow) and carrier-­based root filling in buccal canal (high magnification, 24×); (d) resected root surface of a
mesiobuccal root of a maxillary molar with microfracture (arrows, 24×); (e) maxillary premolar (mirror view) with missed palatal canal and
faint isthmus line (arrows) that must be prepared and filled, connecting to the buccal canal (24×); and (f) maxillary central incisor (mirror
view) with insufficient root filling and debris remnants (arrow) between gutta-­percha and canal walls (24×) [FS].

Ferric sulphate (Stasis 21%; Midway Dental Supply toxic components that might have adverse effects on heal-
Co.) is a chemical agent that achieves haemostasis by ag- ing (Haasch et al., 1989; Ibarrola et al., 1985; Jeansonne
glutination of blood proteins that occlude the capillary et al., 1993; Lemon et al., 1993) and allow the osteotomy
orifices after a reaction of the blood with both ferric and site to fill in with blood.
sulphate ions under the acidic condition (pH 0.21) of the Methylene blue (Vista Apex Dental Products), a thi-
solution (Evans, 1977). The use of ferric sulphate results azine dye, is used to stain the resected root surface (Kim
in an immediate chemical reaction and does not require & Kratchman, 2006; Figure 36a) after drying it with a
the application of backpressure (Figure 35). However, fer- small irrigator, such as the Stropko device (Stropko
ric sulphate is cytotoxic and may cause tissue necrosis if et al., 2005; Stropko irrigator; Vista Apex Dental
left behind in the osteotomy site. It may have significant Products; Figure 36b). The dye will stain the circum-
adverse effects on osseous healing (Lemon et al., 1993) ference of the periodontal ligament to verify complete
and must be thoroughly flushed out with saline to avoid resection and to detect missed canals (Figure 36c), mi-
impaired healing. crofractures (Figure 36d), isthmuses (Figure 36e), other
Aluminium chloride (Expasyl, Acteon) is a haemo- anatomical details, aberrations or iatrogenic errors
static agent with a working mechanism similar to fer- (Figure 36e). The inspection of the resected root surface
ric sulphate. It has been compared to a variety of other must be carried out at high magnification (16×–­24×;
means to establish surgical haemostasis (Menendez-­ Kim & Kratchman, 2006; Von Arx et al., 2011). Canal
Nieto et al., 2016; Penarrocha-­Oltra, Menendez-­Nieto, isthmuses are narrow, ribbon-­shaped communications
et al., 2019; Penarrocha-­Oltra, Soto-­Penaloza, et al., 2019; between two root canals that contain pulpal tissues
Peñarrocha-­Oltra et al., 2022). A systematic review and (Weller et al., 1995). An isthmus is a part of the canal
meta-­analysis by Khater et al. (2021) found aluminium system and not a separate entity. It must be cleaned,
chloride to rank first in bleeding control during endodon- shaped and filled as thoroughly as other parts of the root
tic surgery, albeit with a low quality of evidence. From a canal system. At a 3-­mm resection level from the origi-
clinical perspective, the paste-­like consistency causes it to nal apex, isthmuses were found at 90% of the mesiobuc-
adhere well to the osteotomy site and may require bony cal roots of maxillary first molars, 30% of the maxillary
curettage for effective removal in addition to saline irri- and mandibular premolars, and over 80% of the mesial
gation for removal. By the end of the surgical procedure, roots of the mandibular first molars (Hsu & Kim, 1997;
all haemostatic agents must be removed to clear away any Weller et al., 1995). An evaluation of unsuccessful cases
20 |    SURGICAL ENDODONTICS

identified mismanagement or failure to manage isthmus material and the root canal wall or due to anastomoses
spaces as the main cause of failure in mesial roots of between canals. Even fine isthmuses connecting main
molars (Hsu & Kim, 1997). canals should be cleaned during root-­ end preparation
(Mannocci et al., 2005; Figure 37). A root-­end preparation
will also greatly diminish bacteria inside dentinal tubules,
Root-­end preparation as the majority of bacteria in the apical third of a root are
located in the dentine immediately adjacent to the root
Root-­end preparation aims at disinfecting portions of a canal (Jolly & Sullivan, 1956; Shovelton, 1964). A root-­end
root canal system that had been left untreated by earlier preparation is a Class 1 cavity with walls parallel to and
endodontic therapy, including previously non-­negotiated coincident with the anatomy of the root canal space (Carr,
canals and cases where the quality of the existing root 1994).
filling is unsatisfactory, either due to insufficiency of the Root-­end preparation as part of endodontic micro-
sealer materials to fill the spaces between the core filling surgery is carried out using ultrasonic tips (Sultan & Pitt
Ford, 1995; Figure 38). It is important to orient the ultra-
sonic tip in the direction of the long axis of the root at
low magnification (4×–­8×; Figure 39). Tip variations with
different angulations exist for different sections of the
jaw. Whilst ultrasonic tools had been under suspicion to
create cracks in the dentine after root-­end preparation
(Frank et al., 1996; Layton et al., 1996), these concerns
do not seem to be relevant to the clinical outcome (Beling
et al., 1997). A practitioner should choose tip sizes and an-
gulations dependent on the original shape and size of the
root canal (Figure 38). Before placing a root-­end filling, the
retrograde cavity must be dried using the micro-­irrigator
and inspected at high magnification using a micro-­mirror
F I G U R E 3 7 Completed root-­end preparation (arrow) in the to verify that all filling materials in the cavity were re-
mesial root of a mandibular left first molar. The mesiobuccal and moved completely (Stropko et al., 2005; Figure 40). Filling
mesiolingual canals were connected by an isthmus, which was remnants are often still detected in the buccal aspect of the
prepared into a single cavity. The root-­end cavity must be dry prior cavity, as this portion of the root canal wall cannot be di-
to placement of the root-­end filling [FS]. rectly observed during ultrasonic preparation (Figure 41).

F I G U R E 3 8 Piezoelectric and ultrasonic attachments. Upper left: piezoelectric attachments for placement of a protective groove, bone
window technique and general osteotomy (Woodpecker Medical Instruments Co.). Lower left: piezoelectric tips for root-­end preparation
and refinement of bony crypt (Woodpecker). Upper right: diamond-­coated KiS ultrasonic root-­end preparation tips (Obtura Spartan
Endodontics). General-­purpose tips for smaller and larger canals in anterior and posterior areas; and buccal and lingual (left & right) tips
with 75° or 110° angulation for premolar and molar access. Lower right: ultrawave ultrasonic retrograde instrumentation tips (Acteon
Satelec, Acteon North America) in 3-­, 6-­and 9-­mm length for deep cavity preparations.
SETZER and KRATCHMAN    | 21

bacteriostatic properties would also be preferential, con-

sidering the overall purpose of treatment. A root-­end fill-
ing material should also show good adhesion to the root
canal wall, dimensional stability, noncorrosiveness, resist-
ance to dissolution and ease of manipulation with an ad-
equate working time. It should not stain teeth or tissues,
exhibit osteo-­and cementogenic properties, and be radi-
opaque. Over time, a wide range of root-­end filling ma-
terials have been introduced, investigated and reviewed
(Chong & Pitt Ford, 2005; Johnson, 1999. Common mate-
rials that have been investigated in clinical studies include
amalgam (Del Fabbro et al., 2007; Harty et al., 1970), gutta-­
F I G U R E 3 9 Alignment of the ultrasonic tip in the direction of percha (Frank et al., 1996; Persson, 1964), zinc oxide/cal-
the longitudinal axis of the root (black arrow) at mid-­magnification cium sulphate types of cement (Cavit; Finne et al., 1977;
(ca. 12×) [FS]. Nord, 1970; Persson et al., 1974), polyvinyl resin (Diaket;
Tetsch, 1986), glass–­ ionomer cement (Bronkhorst
et al., 2008), composite resin (Geristore, RetroPlast; Al-­
Sabek et al., 2005), zinc oxide/eugenol cement (IRM,
SuperEBA) and calcium silicate types of cement (mineral
trioxide aggregate (MTA), biodentine and bioceramic root
repair material (BC, RRM)). With the exception of amal-
gam, which was included due to its historical importance
and because it may still be used (Bronkhorst et al., 2008),
only the most contemporary root-­end filling materials are
discussed below.
Amalgam was found to be the most popular and widely
used root-­ end filling material (Block & Bushell, 1982;
Friedman, 1991; Von Hippel, 1914). It has been criticized
F I G U R E 4 0 Inspection of the root-­end cavity prior to root-­ for lack of biocompatibility, corrosion, a risk of crack for-
end filing at high magnification (24×). The adequate depth and mation in the root apex, hard tissue staining and soft tissue
complete removal of filling remnants on the canal walls must be tattoos due to silver salts (Harrison & Johnson, 1997), and
ensured [FS].
poor prognosis (Allen et al., 1989; Dorn & Gartner, 1990;
Finne et al., 1977; Jesslén et al., 1995; Pantschev
et al., 1994; Setzer et al., 2010). The leakage of amalgam
was found using dye penetration tests (Friedman, 1991;
Olson et al., 1990) or the fluid filtration model (Spangberg
et al., 1989; Wu et al., 1990). Critics pointed out that these
were not in vivo conditions (Peters & Harrison, 1992;
Roda & Gutmann, 1995). However, amalgam also demon-
strated bacterial leakage (Chong et al., 1995; Torabinejad,
Hong, Ford, et al., 1995; Torabinejad, Hong, McDonald,
et al., 1995; Torabinejad, Rastegar, et al., 1995), consis-
tently allowing for greater leakage than any other ma-
terial, independent of the methods (Chong et al., 1995).
F I G U R E 4 1 Schematic representation of the most challenging Therefore, amalgam is likely to leak as a root-­end fill-
area to instrument and to inspect the buccal aspect of the root canal ing material as well (Andreasen & Rud, 1972; Chong
walls (arrow). et al., 1995; Gutmann & Harrison, 1991). Amalgam's lack
of biocompatibility stems from the mercury content in the
metal alloy mixture. Mercury is an environmental hazard
Root-­end filling and has great scrutiny attached to its use as a restorative
filling material (Eley & Cox, 1993). Histologically, amal-
An ideal root-­end filling material has to be biocompatible gam and its corrosion products repeatedly demonstrated
and demonstrate excellent sealing ability. Bactericidal or unfavourable inflammatory tissue responses (Baek et al.,
22 |    SURGICAL ENDODONTICS

2005, Chong et al., 1997), with traces of amalgam still

detectable from the root end (Peters & Harrison, 1992).
Amongst all materials compared, amalgam showed the
most severe and extensive periapical tissue inflammation
(Chong et al., 1997; Peters & Harrison, 1992; Pitt Ford
et al., 1995a, 1995b; Pitt Ford, Torabinejad, et al., 1995;
Torabinejad, Hong, Ford, et al., 1995; Torabinejad, Hong,
McDonald, et al., 1995; Torabinejad, Rastegar, et al., 1995;
Torabinejad et al., 1997).
Composite resins exhibited good sealing abilities as
a root-­end filling material in vitro (Adamo et al., 1999;
McDonald & Dumsha, 1987, 1990). Geristore (Den-­Mat),
a dual-­curing hydrophilic modified composite resin, has F I G U R E 4 2 Placement of bioceramic root repair material
been used for conventional root-­end filling and the repair (RRM) as root-­end filling material using a microsurgical plastic
of subgingival or subosseous defects and as a barrier ma- instrument [FS].
terial for guided tissue regeneration (GTR). A resin-­based
technique to seal the resected root apex was first intro- better outcomes than amalgam (Dorn & Gartner, 1990;
duced by Rud et al. (1991) and more recently used by von Rubinstein & Kim, 1999, 2002). Histologically, they are
Arx et al. (2010). The protocol requires the preparation of more biocompatible than unmodified ZOE, although some
a concave cavity over the entire resected root surface by inflammatory cells on the root surface were still observed
a round bur, which is then etched with EDTA, and filled (Peters & Harrison, 1992; Pitt Ford et al., 1992; Pitt Ford
over with a bonded resin material in a domelike fashion. et al., 1995a, 1995b; Pitt Ford, Torabinejad, et al., 1995).
The material most frequently used with this technique Both IRM and SuperEBA display low solubility (Chong
is RetroPlast (RetroPlast; RetroPlast Trading), a dentine-­ et al., 1994), good antibacterial action (Chong et al., 1994;
bonded dual-­curing composite resin (Rud et al., 1991; von Torabinejad, Hong, Ford, et al., 1995; Torabinejad, Hong,
Arx et al., 2010). Although being incorporated into a mi- McDonald, et al., 1995; Torabinejad, Rastegar, et al., 1995)
crosurgical approach, this technique differs significantly and little leakage in dye penetration tests (Chong
from other approaches, as no conventional root-­end cavity et al., 1994; O'Connor et al., 1995). SuperEBA demon-
is prepared, and no conventional root-­end filling is placed. strated significantly less leakage and better root wall ad-
Whilst this resin-­based technique has produced fa- aptation compared to amalgam. Clinical studies that used
vourable results compared to traditional root-­end surgery either IRM or SuperEBA as root-­end filling materials, in
techniques (Jensen et al., 2002;Rud et al., 1996a, 1996b), combination with ultrasonic root-­end preparation and the
it has demonstrated a lower weighted pooled success rate use of high magnification, qualify for inclusion in a meta-­
compared to contemporary techniques (Kohli et al., 2018). analysis evaluating the outcome of endodontic microsur-
Most practitioners may limit its indications to situations gery (Kohli et al., 2018; Setzer et al., 2010, 2012).
where a root-­end cavity cannot be prepared with ultra- Calcium silicate cements are dental materials that were
sonic tips, for example if a post reaches close to the end originally derived from Portland cement, a silica, alumina
of a root. The technique requires moisture control beyond and calcium compound construction material. To date, a va-
the haemostasis provided with regular bleeding control riety of dental filling and repair materials have been devel-
during surgery to allow for favourable dentine bonding to oped, including mineral trioxide aggregate (MTA; Dentsply
the resected root surface (Rud et al., 1996a, 1996b), which Sirona), Biodentine (Septodont USA) or Bioceramic root
may be the major disadvantage of the procedure. repair material (BC, RRM; Figure 42). All calcium silicate
Zinc oxide eugenol (ZOE) cement was recom- cements are hydrophilic, but there are differences in set-
mended and used in root-­end surgery for many decades ting time and methods of preparation. Calcium silicate
(Garcia, 1937; Nichols, 1965). The two most widely ac- cements offer significant improvements compared with
cepted materials are intermediate restorative material ZOE cements, including reduced cytotoxicity (Bortoluzzi
(IRM; Dentsply Caulk), a ZOE cement reinforced by et al., 2015; Collado-­González et al., 2017), increased bio-
the addition of polymethacrylate to the powder, and su- compatibility (Gilheany et al., 1994; Mestieri et al., 2015),
perethoxybenzoic acid (SuperEBA; Harry J Bosworth increased cell attachment (Collado-­González et al., 2017),
Company), modified by the partial substitution of eu- cemento-­and osteoinductive properties (Chen et al., 2016;
genol liquid for orthoethoxybenzoic acid with the ad- Gilheany et al., 1994), and increased pH values (Grech
dition of fused quartz or aluminium oxide (alumina) to et al., 2013). MTA was the first calcium silicate cement to
the powder. Both materials demonstrated significantly be introduced in Endodontics (Torabinejad, Hong, Ford,
SETZER and KRATCHMAN    | 23

BC or RRM, which only differ in particle size. These mate-

rials alleviated some of the concerns that had arisen with
MTA. Both Biodentine and RRM exhibit less tooth dis-
coloration than MTA (Kohli et al., 2015). RRM has been
more widely applied as a root-­end filling material than
Biodentine, which is more often used for perforation repair.
RRM is dimensionally stable, demonstrates a high pH and
is as short as 2–­4 h of setting time. RRM and MTA are not
significantly different in their antimicrobial efficacy
(Lovato & Sedgley, 2011), biocompatibility (Alanezi
et al., 2010) and sealing ability (Nair et al., 2011). An in
vivo study comparing RRM and MTA as root-­end filling
materials (Chen et al., 2015) demonstrated no or only
minimal inflammation at the surgical site upon healing,
with cementum-­like tissues observed adjacent to RRM,
comparable to previous findings for MTA (Figure 43).
Two randomized controlled trials investigating endodon-
F I G U R E 4 3 Histology of a root-­end surface after retrograde
tic microsurgery have shown highly favourable outcomes
filling with RRM and 6-­month healing period in canines. No
inflammatory cells were identified near the root canal exit in the (Shinbori et al., 2015; Zhou et al., 2017).
periapical area. RRM remnants within the periapical tissues did not
induce an inflammatory reaction (yellow arrow). Cementum-­like
tissue formed on the resected root surface and RRM root-­end filling Guided tissue regeneration (GTR)
(green arrow) with fibrous insertion from the adjacent periodontal
ligament-­like tissue. From Shin et al. (2017). After completing a surgical procedure, the osteotomy site
must be inspected and cleaned of any excess materials and
et al., 1995; Torabinejad, Hong, McDonald, et al., 1995; haemostatic agents to avoid foreign body reactions and to
Torabinejad, Rastegar, et al., 1995) and has been compre- remove any toxic by-­products. Blood should fill back into
hensively investigated. Histologically, MTA demonstrated the osteotomy site so that the formation of a blood clot
considerably less inflammation around root-­end fillings and subsequent osseous healing can take place. Grafting
in in vivo studies (Baek et al., 2005; Regan et al., 2002; materials or membranes should be placed at this stage of
Torabinejad, Hong, Ford, et al., 1995; Torabinejad, Hong, the procedure. Whilst extensively used in periodontology
McDonald, et al., 1995; Torabinejad, Rastegar, et al., 1995; and implant dentistry, the use of GTR techniques is far
Torabinejad et al., 1997). New cementum and periodontal less common in endodontics (Tsesis et al., 2011), and the
ligament structure have frequently been shown to form scientific evidence for the benefit of its use was considered
over a resected root surface and the root-­end filling itself low (Corbella et al., 2015). Membranes to separate bone
(Torabinejad, Hong, Ford, et al., 1995; Torabinejad, Hong, healing from connective tissue healing were introduced
McDonald, et al., 1995; Torabinejad, Rastegar, et al., 1995; for dentoalveolar applications in the 1960s (Boyne, 1969).
Torabinejad et al., 1997). The formation of a hydroxyapa- Membranes for endodontic surgery were investigated in
tite (HA) layer on the MTA surface in contact with tissue animal studies (Dahlin et al., 1990; Maguire et al., 1998)
fluid during the setting of the material, described as ‘bio- and in patients (Pecora et al., 1995). Common materials
mineralization’, has been observed (Bird et al., 2012). This for GTR include polytetrafluoroethylene (ePTFE, Gore-­
layer may create a biological seal between MTA and the Tex), collagen or polylactide for membranes; and freeze-­
dentine interface and may enhance its long-­term sealing dried bone allografts, demineralized freeze-­ dried bone
ability. Disadvantages of MTA include handling proper- allografts, HA, tricalcium phosphate, bioglass or calcium
ties and possible tooth discoloration, for both its grey and sulphate for grafts. GTR prevents epithelial ingrowth into
white formulations (Kohli et al., 2015). Freshly mixed lesions and therefore allows bone regeneration in compar-
MTA has the consistency of a moist, granular paste, and it ison with control lesions without the use of barriers (Baek
may be difficult to place into a root-­end cavity. It may also & Kim, 2001; Villar & Cochran, 2010).
wash out in the presence of excessive bleeding or other GTR for endodontic surgery was subject to review
tissue fluids, which may compromise its sealing ability. (Corbella et al., 2015; Deng et al., 2016; Lin et al., 2010;
Newer versions of calcium silicate cements have been Sumangali et al., 2021; Tsesis et al., 2011; Zubizarreta-­
introduced, including Biodentine, a capsule-­based mate- Macho et al., 2022). For the application of GTR in end-
rial that has to be mixed in a triturator, and the premixed odontic surgery, a distinction can be made between
24 |    SURGICAL ENDODONTICS

uncomplicated defects, complicated defects and peri- increased effectiveness of combinations of membranes
odontally involved defects. Uncomplicated defects are and bone replacement analogues. However, the same
true endodontic lesions without any periodontal com- study also concluded that the singular use of bone re-
ponent, such as deep probings on the tooth or a connec- placement materials improved the surgical outcome for
tion between concomitant periodontal and endodontic endodontic surgery, which was not confirmed by a re-
defects. For uncomplicated defects, the healing rate with cent network meta-­analysis for bone graft materials alone
or without membrane placement did not demonstrate (Zubizarreta-­ Macho et al., 2022). Zubizarreta-­Macho
any differences (Maguire et al., 1998), similarly for the et al. (2022) appraised the clinical evidence on the efficacy
placement of a membrane combined with graft at a 1-­year of GTR techniques and included 11 randomized clini-
recall (Taschieri et al., 2007). Evaluated by CT imaging, cal trials comparing six GRT techniques, including bone
periapical bone healing and bone density after 6 months graft, membrane, membrane plus bone graft, platelet-­rich
of follow-­ up did not exhibit differences (Santamaria plasma or membrane plus platelet-­rich plasma. Both the
et al., 1998). Complicated defects are endodontic lesions membrane and the membrane plus bone graft techniques
with a defect size exceeding 10 mm in diameter, ‘through-­ demonstrated statistically significant odds ratios com-
and-­through’ lesions with a bucco-­lingual defect, and/or pared to procedures conducted without GTR.
perforation to the nasal cavity or a large maxillary sinus Periodontally involved defects may display apico-­
perforation. marginal or perio-­endo communication defects, bone loss in
Complicated defects may benefit from GTR. Membrane the furcation, or a loss of the buccal plate due to dehiscence
placement on both the buccal and lingual aspects of or completely denuded root. The use of GTR techniques
‘through-­and-­through’ rat calvaria defects showed com- for chronic periodontic-­endodontic lesions was evaluated
plete healing versus no healing without membranes in by Britain et al. (2005). da Silva Pereira (2000) suggested
the control group (Bohning et al., 1999). In similar de- that the combined use of a membrane and graft may sig-
fects, complete healing after endodontic surgery could nificantly increase cementum deposition in situations with
be seen when a barrier was used versus controls that complete buccal plate loss. The overall success rate for end-
showed only fibrous connective tissue (Dahlin et al., 1988; odontic surgery is significantly decreased for periodontally
Dahlin et al., 1990). Azim et al. (2020) confirmed that involved defects compared to endodontic lesions alone (Kim
the quality of apical bone remodelling after endodontic et al., 2008; Song, Shin, et al., 2011; Song, Jung, et al., 2011).
surgery was improved with GTR techniques. In patients,
healing of through-­and-­through lesions was observed in
88% with GTR placement versus 57% without (Taschieri Wound closure and postoperative care
et al., 2008). Taking these findings together indicates that
for through-­and-­through lesions, both buccal and lingual After an osteotomy site has been cleaned and any appro-
barriers should be placed for effective healing (Bohning priate grafts or membranes have been placed, the surgi-
et al., 1999). Lesions exceeding 10 mm in diameter healed cal flap can be repositioned and sutured. Wound closure
faster and with better outcomes when GTR was used and postoperative care will have a great effect on the bio-
versus without (Pecora et al., 1995; Pecora et al., 2001), logic and aesthetic healing process. The soft tissue should
including radiographic, clinical and histologic results be moistened with a wet gauze containing saline before
(Pecora et al., 1995; Rankow & Krasner, 1996; Tobon the repositioning of the flap to ensure that dehydration
et al., 2002). However, the healing of lesions measuring during the surgery will not have a negative effect on the
10 mm or larger in diameter combined with a loss of both natural elasticity of the tissues. Sutures will be necessary
the buccal and lingual cortical plates remained unaffected to replace the mucoperiosteal flap in its original posi-
by the placement of resorbable collagen membranes ac- tion. A microscope or loupes should be used for smaller
cording to both two-­and three-­dimensional evaluation suture diameters. Today, common sutures for endodon-
(Parmar et al., 2019). tic microsurgery are monofilament sutures that range
A systematic appraisal of the literature demonstrated in diameter between 5–­0 and 6–­0 for standard interven-
some general improvement in surgical endodontic out- tions and between 6–­0 and 7–­0 for aesthetically demand-
comes by GTR techniques. Sumangali et al. (2021) con- ing areas, such as the anterior maxilla or when a papilla
ducted a systematic review and meta-­analysis evaluating base incision was performed. Traditional silk sutures may
various bone regenerative materials for periradicular promote bacterial growth and impede wound healing.
surgery. Their meta-­analysis showed higher success rates Nylon, polypropylene, or polytetrafluoroethylene (PTFE)
when bone graft materials were used in conjunction with monofilament or coated monofilament sutures have be-
barrier materials. These findings concurred with the come the material of choice for endodontic microsurgery
meta-­analysis by Deng et al. (2016), who confirmed the (Velvart et al., 2005a, 2005b). Contact to the underlying
SETZER and KRATCHMAN    | 25

(a) (b) (c)

F I G U R E 4 4 Flap repositioning and suturing. (a) Submarginal incision, single interrupted 6-­0 monofilament sutures; (b) sling suture
around mandibular left first molar. The needle enters mesiobuccally of the molar, slings around the lingual portion of the tooth, and exits
and enters distobuccally (arrow) again to complete the sling suture with a mesiobuccal knot (no puncturing of lingual tissue); and (c)
repositioning of the flap at the mesial vertical releasing incision at high magnification (24×) [FS].

F I G U R E 4 5 Three basic phases

of wound healing: Inflammation,
proliferation and remodelling. From
Dapkute et al. (2017).

bone is needed to establish stable conditions, minimize cooling with an ice pack will prevent excessive swelling
the thickness of the subperiosteal blood clot and allow for (Gutmann, 2005; Gutmann & Harrison, 1991).
healing by primary intention. Whilst resorbable sutures, Patients need to be informed that besides swelling and
such as gut, may reduce the number of office visits, an pain, temporary discoloration and bruising may occur in a
inflammatory component is added to the wound healing small number of patients. Nonsteroidal anti-­inflammatory
process by resorption of the suture. A suture removal ap- drugs (NSAIDs) are the first choice as analgesics if the pa-
pointment allows the practitioner to check on the patient tient can tolerate this type of drug. Antibiotic coverage is
48 h (Gutmann & Harrison, 1991) to 4 days (Gutmann & not advised on a general basis (Gutmann, 2005) but may be
Harrison, 1985; Velvart & Peters, 2005) after the proce- needed based on the patient's medical or dental history or,
dure. If sutures remain too long, some flap margins may for example, a large opening of the maxillary sinus during
be compromised by infection (Grung, 1973; Gutmann & the procedure. A chlorhexidine rinse after the first day will
Harrison, 1991). Needle size, shape and curvature are im- allow for better wound healing, as it reduces bacterial con-
portant, but its selection may depend on the periodontal tent in the oral cavity and therefore reduces the risks of
biotype, the ability to access the area and the preference postoperative infection. The patient should receive contact
of the clinician (Velvart et al., 2005a, 2005b). Single inter- information for after-­hour emergencies and instructions
rupted sutures allow for a better readaptation than con- on when they should return for follow-­up. It is advisable
tinuous sutures (Figure 44a,b). A sling suture is useful for to have the patient return after 4 weeks for a follow-­up to
interproximal readaptation in the posterior (Figure 44c). check soft tissue healing and the absence of any clinical
Instructions for a patient include avoiding exercise for symptoms. Clinical and radiographic follow-­ups should
1–­2 days and not pulling up their lips or cheeks to prevent take place after 1, 2 and 4 years to observe the healing pro-
any unnecessary disturbance of the flap, which could cess and ensure that long-­term success is guaranteed.
result in bleeding or open up flap margins. The under-
lying blood clot must be protected from any postopera-
tive risk of infection, which may be associated with pain Modes of healing
and swelling, or delayed healing. The patient should not
smoke for as long as possible and choose food that can During the healing phase of the periapical tissues, stem
easily be cleaned away from the surgical site. Intermittent and progenitor cells are recruited from the bone marrow,
26 |    SURGICAL ENDODONTICS

endosteum, periosteum and the periodontal ligament which was not observed for SuperEBA or amalgam (Baek
(PDL) to differentiate into osteoblasts fibroblasts and ce- et al., 2010).
mentoblasts. An excisional wound after surgery will heal
faster than a granuloma or cyst after nonsurgical treat-
ment, as the inflamed tissues must first be broken down Outcome of surgical endodontics
by phagocytic debridement (Lin et al., 2010). After endo-
dontic surgery, the osteotomy site is filled with blood. The The most widely used criteria to assess the outcome of en-
repositioned flap will protect the blood clot from microbes dodontic surgery were based on Rud and Molven (Molven
present within the oral cavity. Epithelial cells will prolif- et al., 1987; Rud et al., 1972). The authors defined radiographic
erate to close surgical incision wound. Healing will occur success as complete healing or incomplete (scar tissue for-
as two separate processes below the soft tissues, osseous mation) healing and clinical success as the absence of pain,
healing and dentoalveolar healing. swelling, percussion sensitivity or a sinus tract. Radiographic
Osseous healing requires haemostasis by vasoconstric- failure includes uncertain healing (reduced lesion size) and
tion and platelet aggregation (Lin et al., 2010). There are unsatisfactory healing (unchanged or increased lesion size),
three basic phases of wound healing, which considerably whilst clinical failure means the presence of any of the symp-
overlap: inflammation, proliferation and remodelling toms described above. According to Molven et al. (1987),
(Kumar et al., 2009; Figure 45). Within these three phases, healing-­related changes after surgery occur predominantly
a complex and coordinated series of events occurs. The in- within the first year. Cases that were considered uncertain
flammatory phase includes chemotaxis and phagocytosis healing should be re-­evaluated for up to 4 years.
(Kumar et al., 2009). During the proliferation phase, neo- If all historical techniques are included, surgical
collagenesis, epithelialization and angiogenesis result in success may range from 37% to 91%, varying with the
the formation of a granulation tissue that originates from operator and the specific techniques (Friedman, 2005).
the PDL and the endosteum (Harrison & Jurosky, 1992; Great variations in treatment protocol and methodology
Kumar et al., 2009; Majno & Joris, 2004). In the remod- exist between different studies. Therefore, the interpre-
elling phase, active collagen remodelling and tissue mat- tation of the outcome has to be undertaken cautiously.
uration take place, which may result either in repair or in Variables include study design, sample sizes, inclu-
regeneration (Kumar et al., 2009). For the osseous wound, sion and exclusion criteria, follow-­up periods, lack of
this results in a sequence of revascularization of the ini- standardized clinical and radiographic parameters for
tial blood clot and the formation of a mineralizing matrix, healing, the periodontal condition of the teeth prior to
from which woven bone eventually matures into cancel- surgery, variations in the quality of previous endodontic
lous bone. New bone formation starts in the centre and treatment, the coronal restoration, and the surgical ma-
progresses externally towards the level of the former cor- terials and techniques itself. Moreover, many historical
tical plate. When new woven bone approaches the lamina studies were case series or other studies with a low level
propria, the overlying membrane matures into functional of evidence (Mead et al., 2005).
periodontium. The differences in outcome for endodontic surgery
During the dentoalveolar healing process, viable PDL depending on the techniques used in individual studies
cells from the adjacent root surface will proliferate and have been documented by systematic reviews and meta-­
cover the denuded resected root (Lin et al., 2010). These analyses. Traditional, now obsolete techniques using
PDL stem cells will differentiate into cementoblast-­ a straight surgical handpiece, a bevelled root resection
like cells and eventually regenerate cementum (Lin and often a retrograde amalgam filling demonstrated a
et al., 2010; Lin & Rosenberg, 2011). Root resorption that weighted pooled success rate of 59.0% (Setzer et al., 2010).
involves both cementum and dentine can only be repaired The use of loupes, ultrasonic root-­end preparation and
by cementoid tissues, as PDL stem cells can not differ- more biocompatible filling materials increased cumulative
entiate into odontoblasts. In the absence of infection or success to 86% (Setzer et al., 2012). Endodontic microsur-
severe inflammation, the cementum can grow back to gery, using the same tools and techniques, only replacing
cover the resected dentine surface (Andreasen, 1973, loupes with a dental operating microscope allowing for
1981; Harrison & Jurosky, 1992; Rowe, 1967). Both MTA high magnification, demonstrated even higher success
and RRM allow cementum to apposition directly on the rates ranging from 91.4% to 94.4% for true endodontic le-
surface of the materials (Chen et al., 2015; Torabinejad, sions (Kohli et al., 2018; Setzer et al., 2010; Torabinejad
Hong, Ford, et al., 1995; Torabinejad, Hong, McDonald, et al., 2015; Tsesis et al., 2013; Figure 46). Resin-­based
et al., 1995; Torabinejad, Rastegar, et al., 1995; Torabinejad endodontic surgery, using a concave cavity and a dome-­
et al., 1997). Moreover, MTA may support the reestablish- shaped composite filling, demonstrated a weighted pooled
ment of a PDL width comparable to its natural thickness, success rate of 82.2% (Kohli et al., 2018). BC RRM has
SETZER and KRATCHMAN    | 27

(a) (b) (c)

(d) (e) (f)

F I G U R E 4 6 Long-­term follow-­up after endodontic microsurgery. (a) Preoperative radiograph, the patient had received traditional root-­
end surgery with retrograde amalgam fillings several years ago and presented with percussion and palpation sensitivity on the maxillary
left first molar; (b, c) postoperative radiographs after endodontic microsurgery with bioceramic RRM root-­end fillings; (d) 2-­year follow-­up,
complete bony regeneration, the patient is free from clinical symptoms; and (e) 3-­year follow-­up and (f) 5-­year follow-­up show no changes or
reversal of the successful outcome [FS].

been successfully used as an alternative to mineral triox- Kim and Kratchman (2006) developed a microsurgical clas-
ide aggregate, with success rates ranging between 92.0 and sification where true endodontic lesions are characterized
94.4% (Shinbori et al., 2015; Zhou et al., 2017). as Classes A through C. Briefly, Class A represents a case
However, a reversal of healing after periradicular sur- with unresolved symptoms after nonsurgical approaches
gery has often been debated. Del Fabbro et al. (2007) as- have failed but without a lesion present on a periradicu-
sessed randomized clinical trials comparing nonsurgical lar radiograph; Class B, a small periapical lesion together
versus surgical retreatment. The authors described faster with clinical symptoms; and Class C, a large periapical le-
healing after the surgical procedure after 1 year but a re- sion progressing coronally but without periodontal pocket
gression of successful cases for endodontic surgery over and mobility. In contrast, periodontally compromised teeth
a follow-­up period of 4 years (Del Fabbro et al., 2007). represent Classes D through F, with Class D being sim-
Friedman made similar assertions reviewing the outcome ilar to those in class C but with deep periodontal pockets;
of endodontic surgery (Friedman, 2011). However, the Class E represents a periapical lesion with an endodontic–­
majority of the healing reversals described can be iden- periodontal communication; and Class F represents an api-
tified as relating to now obsolete techniques, including cal lesion and complete denudement of the buccal plate.
retrograde gutta-­percha or amalgam fillings. There are Kim et al. (2008) compared teeth undergoing endodon-
abundant data today that confirm that surgical procedures tic microsurgery depending on the microsurgical classifi-
with modern techniques and proper case selection do not cation described above. The difference in success between
undergo excessive failure rates. However, as with all den- teeth in Classes A–­C was 95.2% versus a success rate of
tal procedures, there is attrition of cases that were labelled 77.5% for the periodontally compromised teeth in Classes
successful at follow-­up. According to Song et al. (2012)), D–­F, which was statistically significant (Kim et al., 2008).
teeth that had undergone surgery using microsurgical The lowest success rates were observed for cases with
techniques demonstrated a success rate of 93.3% for more probing to the apex of the root with or without complete
than 6 years. Cases that were considered unsuccessful loss of the buccal cortical plate.
frequently exhibited failure patterns associated with root
fractures or operator mistakes, including missing root-­end
fillings, incorrect root-­end preparation, missed canals, or Crown and root resection
unaddressed and leaking isthmuses (Song et al., 2012).
The studies described above largely assessed cases of end- Root amputation procedures were first introduced for the
odontic surgery that are considered true endodontic lesions. treatment of multi-­rooted teeth with furcation involvement
28 |    SURGICAL ENDODONTICS

(Faulhaber & Neumann, 1912). Root amputation is con- remaining crown section must be contoured to ensure that
sidered a ‘root resection’ technique as it only involves no undercuts remain, which could be attractive to plaque.
the removal of root structure below or at the level of the All granulation tissues must be removed, the root surfaces
cementoenamel junction without removal of portions of cleaned, and an osteoplasty performed for the remain-
the crown (Setzer et al., 2019). In contrast, ‘crown resec- ing bone to eliminate any irregularities and to provide a
tion’ includes hemisection, trisection and premolarization sound biologic width for the dentogingival complex. The
(bicuspidization), respectively, and all procedures where flap should then be repositioned and sutured. Follow-­up
a dissection transverses through the furcation and the instructions follow the same guidelines as for root-­end
crown of a multi-­rooted tooth so that a root and the asso- surgery. The definitive restoration, if it remains or be it
ciated portion of the crown may be removed (hemisection, renewed, should allow good hygiene access.
trisection) or all root/crown sections are being retained A number of clinical studies (Bergenholtz, 1972;
(premolarization, bicuspidization; Setzer et al., 2019). Bühler, 1988; Carnevale et al., 1991; Carnevale et al., 1998;
Indications and contraindications for crown and root re- De Beule et al., 2017; Erpenstein, 1983; Fugazzotto, 2001;
section were introduced and further amended (Minsk & Hamp et al., 1989; Hou et al., 1999; Langer et al., 1981; Park
Polson, 2006; Setzer et al., 2019; Staffileno, 1969). et al., 2009; Svärdström & Wennström, 2000; Zafiropoulos
Crown and root resections are indicated for situations et al., 2009) assessed the outcome of crown and root resec-
with severe bone loss affecting one root, not amenable to tion therapies. Survival of the tooth has been validated as
other forms of therapy; moderate to advanced furcation the positive outcome measure for crown and root resection
involvement with divergent roots; unfavourable root (Setzer et al., 2019). A systematic review and meta-­analysis
proximity between adjacent teeth; root fracture, perfo- demonstrated a cumulative survival rate of 85.6% after at
ration, root caries, or external root resorption involving least 1 year, with no statistical difference between crown re-
one root or the furcation area; endodontic treatment of section and root resection techniques (Setzer et al., 2019).
a particular root canal cannot be performed, and root-­
end surgery is contraindicated; a tooth, which is an
abutment of a bridge, can be retained after removal of a FUTURE DIRECTIONS —­R ECENT
particular root; or when anatomical situations preclude ADVANCEMENTS
implant placement.
Crown and root resections are contraindicated if there Over decades, endodontic surgery has evolved into endodon-
is insufficient bone support around the remaining roots tic microsurgery. Whilst the most obvious emphasis is on the
or in the furcation area; the furcation is too close to the inclusion of the surgical operating microscope, ultrasonic
apex, not sufficiently separated, or roots are fused; it is im- root-­end preparation and, today, calcium silicate materials,
possible to perform endodontic treatment in the remain- there are, in fact, many other technical changes that added
ing roots, due to unfavourable anatomy of the remaining to the evolution of endodontic surgery and also Endodontics
roots, extensive caries or root resorption in the furcation as a whole. With the realization of long-­term problems with
area and a minimal strategic value of the remaining root dental implants, such as peri-­implantitis and peri-­implant
structures. mucositis, a shift started to take place to refocus on the re-
Whenever a crown or root resection is considered, tention of natural teeth. There is a renewed interest in pro-
proper endodontic treatment must be carried out prior cedures such as crown and root resections, and other new
to the surgical procedure (Minsk & Polson, 2006). A flap techniques, such as regenerative endodontics, have emerged.
should not be raised before metal restorations are dissected What are the emerging trends for endodontic surgery?
or removed or major areas of dentine have been cut so that
no metallic fragments or tooth particles will be left behind
in the soft tissues. Buccal and lingual full-­thickness mu- Piezoelectric surgery
coperiosteal flaps are indicated for proper surgical access
and visualization to complete the resection and to achieve The piezotome has long had a place in endodontic surgery.
proper wound closure. Any inflammatory tissues must be The preparation of a protective groove for safe anchorage
removed. A long fissure bur or a Lindemann bone-­cutting of surgical retractors is carried out in the safest way with
bur is recommended to remove the root section from a piezoelectric tip, which can not harm soft tissues with
the main trunk of the tooth. The full separation must be its cutting action (Degerliyurt et al., 2009). However, in
verified using a periodontal probe for careful evaluation recent years significant progress has been made regard-
through the furcation and assessment of the mobility ing the development of thinner piezoelectric blades and
of each root. A resected root must be carefully removed more powerful devices. These thinner tips allow for the
to avoid additional damage to adjacent structures. The increased application of the bone ‘window technique’
SETZER and KRATCHMAN    | 29

(a) (b) (c)

(d) (e)

(f) (g) (h)

(i) (j)

F I G U R E 4 7 Bone window technique surgery on a mandibular left first molar. (a) Preoperative radiograph demonstrating a
periradicular lesion around the mesial and distal root ends; (b) CBCT assessment and treatment planning of the bone window (note the
trapezoidal outline of the proposed sections); (c) clinical view of bone window outline cut by piezoelectric tips; (d) HBSS (Sigma-­Aldrich) for
intermediate storage of the cortical plate lid; (e) mesial root-­end filling (arrow); (f) distal root-­end filling (arrow); (g) bone graft placement
(Oragraft MD, Ariston Dental) and repositioning of the cortical plate lid secured by surgical collagen (Morita Foundation®); (h) buccal
placement of a surgical membrane, adaptation with saline (Ossix Plus, Dentsply Sirona), (i) postoperative radiograph with root-­end fillings
in situ; and (j) 1-­year follow-­up shows complete bony regeneration, the patient was free from clinical signs or symptoms. Courtesy Dr Joe
Legg, Scranton, PA, USA.

where a bony lid of the cortical plate is resected, tem- preserve a more bony structure, to maintain the integrity
porarily stored in Hanks Balanced Salt Solution (HBSS) of the healthy cortical plate (Hirsch et al., 2016), and to
and then repositioned at the conclusion of the surgical have easier access to the target roots without the need for
procedure (Lee et al., 2020). The indications for the bone preparation of two separate osteotomies (Figure 47).
window technique are an intact cortical plate of at least With the improvements in piezoelectric surgery, its
1-­mm thickness, close proximity to the sinus or large le- future application may not only be with the creation of
sions involving multiple roots (Lee et al., 2020). The pri- a protective groove or a bone window but its general use
mary aims of performing a bone window technique are to for bone cutting, root resection and root-­end preparation.
30 |    SURGICAL ENDODONTICS

(a) (b) (c)

(d) (e)

(f) (g) (h)

F I G U R E 4 8 Targeted endodontic microsurgery (TEMS) on the palatal root of a maxillary left first molar. (a) Preoperative radiograph,
(b) milled surgical stent, (c) placement of the stent over the palatal mucosa, (d) tissues removed by a trephine bur with 5.0 mm inner
diameter, including palatal mucosa, bone, root tip and sinus floor; (e) trephine bur guided by a surgical stent; (f) micro-­mirror view of root-­
end filling placed in the palatal root (arrow); (g) repositioning and suturing of palatal mucosa punch excision (access was achieved without
flap elevation); and (h) postoperative radiograph. Courtesy Dr Alex Ruch, Exton, PA, USAS.

Ultrasonic vibrations were shown to wash away parti- CBCT healing assessment
cles from the surgical site resulting in less intraoperative
bleeding and better visibility (Goyal et al., 2012; Landes CBCT technology has become commonplace in endo-
et al., 2008; Pappalardo & Guarnieri, 2014). Horton dontic practice with widespread applications. A survey of
et al. (1975) discovered that bone healing was faster after CBCT use completed by 1083 active members of a profes-
using an ultrasonic instrument (piezosurgery) in com- sional Endodontic society identified that the most frequent
parison with a low-­speed rotary bur. The original cortical applications were taken either for diagnostic purposes, for
and cancellous structure of the bone was preserved when example evaluating resorptions or identifying missed ca-
a piezoelectric electric cutting tip was used compared to nals, or for treatment planning for nonsurgical or surgical
a micro-­saw or a Lindemann bur (Maurer et al., 2007). retreatment (Setzer et al., 2017). Only a very small per-
The same study also showed that, histologically, the centage of survey participants reported the use of CBCT
cell viability of the bone at the site of the cut was better for healing assessment. One of the traditional problems
maintained with piezoelectric tools. In a patient study, in endodontic surgery has been the evaluation and clas-
results demonstrated better haemorrhage control during sification of lesions that fall into either the ‘incomplete
surgery, improved quality of life in the first week post-­ healing’ (scar tissue, success) or ‘uncertain healing’ (fail-
surgery, less pain and swelling, and a smaller number of ure) categories for healing assessment. CBCT imaging has
analgesics taken (Bharathi et al., 2021). In conclusion, been confirmed to allow a more precise appraisal of peri-
piezosurgery may be used for more applications than to apical lesions than periapical films. Schloss et al. (2017)
date and make endodontic surgery an even less traumatic demonstrated that cases that were inconclusive in the
experience. healing assessment on two-­ dimensional periapical
SETZER and KRATCHMAN    | 31

radiographs could be clearly assigned to a specific healing and instruments tracked by a stereoscopic vision camera
category using three-­dimensional CBCT imaging. Criteria (Dianat et al., 2021; Gambarini et al., 2019). All these op-
for three-­dimensional assessment of periapical healing tions provide clinicians with previously unknown preci-
after endodontic surgery have been introduced (Chen sion and safety nets during surgical procedures.
et al., 2015; Schloss et al., 2017; von Arx et al., 2016) and During the same time period that guided surgical
since clinically validated (Safi et al., 2019). The future may techniques took hold, the first CBCT-­based endodon-
also see the traditional healing categories to be replaced tic applications for artificial intelligence and its sub-
by strict volumetric assessment of lesions, which has been domain deep learning were developed. Applications
already introduced for a number of clinical evaluations include the development of automated algorithms for
(Curtis et al., 2018; Schloss et al., 2017). Volumetric as- computer-­aided detection and diagnosis (CAD) of peri-
sessment with the aid of semi-­automated or fully auto- apical lesions indicative of apical periodontitis (Orhan
mated lesion segmentation would then allow the clinician et al., 2020; Setzer et al., 2020), the identification of
to assess healing progress in absolute measurements for a cracks (Shah et al., 2018), and the automated segmen-
precise comparison to the preoperative situation. The cur- tation of teeth (Lahoud et al., 2021) and the mandibu-
rent progress in CBCT imaging technology, with the avail- lar nerve canal (Kwak et al., 2020). Early attempts have
ability of limited FOV high-­resolution volume scans with also been made to use deep learning for the differen-
minimal distortion, and radiation doses up to 15 times tial diagnosis of cystic periapical lesions from granu-
lower than conventional CT scans (Scarfe et al., 2009), will lomas (Okada et al., 2015). It will likely not be before
likely continue and increase the ability for practitioners to long that Endodontics will see a coming together of
use CBCT imaging in private practice settings for a more guided surgical techniques with artificial intelligence-­
precise healing assessment. based applications. Artificial intelligence may aid in the
decision-­making if a surgical procedure may be neces-
sary (cyst versus granuloma) and feasible (fracture de-
Guided techniques and artificial tection), and in the treatment planning of the approach
intelligence with automated support for the fabrication of surgical
guides (location of the lesion and the mandibular canal,
The availability of CBCT technology has driven an other anatomy and tooth segmentation). Ultimately, this
entirely new branch of endodontics, with the intro- may culminate in the development and application of
duction of guided surgical techniques in endodontic mi- robotic endodontic microsurgical procedures, which
crosurgery. Guided or targeted endodontic microsurgery have made their first introduction in implant dentistry
­utilizes three-­dimensional printed templates or stents for (Haidar, 2017; Wu et al., 2019).
guided osteotomy and root resection (Ahn et al., 2018;
Giacomino et al., 2018; Strbac et al., 2017). The super-
imposition of preoperative CBCT images with intraoral CONCLUSION
scans allows for the precise planning of the osteotomy size
and location and aids with the three-­dimensional print- Endodontic surgery has a remarkable history and is going
ing of the surgical guides. Variations of the technique in- through a constant evolution with gains in both research
clude access to the osteotomy site with a traditional flap developments and clinical applications. Its current itera-
or in the form of a direct flapless approach. The surgical tion of endodontic microsurgery has been demonstrated
stents were used to guide piezoelectric saws (Strbac et al., to have successful short-­and long-­term outcomes. The
2017), trephine burs (Giacomino et al., 2018) or implant technical armamentarium and materials available for the
drills (Ahn et al., 2018) for osteotomy and root resection. clinician allowed it to become a standard technique for
Targeted endodontic microsurgery has since continued the practitioner specialized in or a focus on Endodontics.
to develop and has since improved with the consolida- The future developments for Endodontic surgery are on
tion of the necessary digital workflows (Ray et al., 2020), the horizon and paint an intriguing picture of the next it-
the detailed assessment of anatomy specific to guided erations of this technique.
surgical techniques, such as the location of the greater
palatine artery (Smith et al., 2021), and the validation of ACKNOWLEDGEMENTS
the techniques by larger case series (Buniag et al., 2021; We want to thank our friends and colleagues, the ‘Penn
Figure 48). Another variation of guided surgical tech- Endo Family’, who have contributed to this article, espe-
niques is dynamic navigation, a freehand approach to en- cially Dr. Syngcuk Kim, all of our’s mentor, who has been
dodontic microsurgery without templates or guides that instrumental in developing Endodontic Microsurgery in
is directed by CBCT location and calibrated surgical burs its current form.
32 |    SURGICAL ENDODONTICS

in ferrets: a pilot study. Oral Surgery, Oral Medicine, Oral

CONFLICT OF INTEREST Pathology, Oral Radiology and Endodontology, 91, 710–­714.
The authors have stated explicitly that there are no con- Baek, S.H., Lee, W.C., Setzer, F.C. & Kim, S. (2010) Periapical bone
flicts of interest in connection with this article. regeneration after endodontic microsurgery with three differ-
ent root-­end filling materials: amalgam, SuperEBA, and min-
DATA AVAILABILITY STATEMENT eral trioxide aggregate. Journal of Endodontics, 36, 1323–­1325.
Data sharing not applicable to this article as no datasets Baek, S.H., Plenk, H., Jr. & Kim, S. (2005) Periapical tissue responses
were generated or analysed during the current study and cementum regeneration with amalgam, SuperEBA, and
MTA as root-­end filling materials. Journal of Endodontics, 31,
444–­449.
ORCID Bharathi, J., Mittal, S., Tewari, S., Tewari, S., Duhan, J., Sangwan, P.
Frank C. Setzer https://orcid.org/0000-0003-0834-1398 et al. (2021) Effect of the piezoelectric device on intraoperative
hemorrhage control and quality of life after endodontic micro-
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