12

Digital Dentistry in Operative Dentistry

DENNIS J. FASBINDER, GISELE F. NEIVA

D
igital technology, computerized dentistry, and digital Clinical Application
dentistry are general terms used to describe the clinical
application of computer-assisted design, computer-assisted Treatment planning considerations for CAD/CAM restorations
machining (CAD/CAM). he restorative dentistry application of are not signiicantly diferent from ceramic restorations done with
CAD/CAM technology is the fabrication and delivery of permanent conventional impression materials and techniques. he CAD/CAM
restorations for teeth and implants. For the past 30 years the system represents an alternative means of restoration fabrication,
incorporation of dental CAD/CAM into direct patient care has not the restoration per se. he type of restoration (inlay, onlay,
provided a way for dentists to deliver esthetic ceramic restorations crown), the choice of material to be used, the desired occlusal
in a single dental appointment. relationships, and ability to isolate the tooth preparation for delivery
here are three sequences involved in the CAD/CAM process.1 of the restoration are several primary factors to consider rather
An intraoral scanner or camera is used to accurately record the than the restoration fabrication process itself. A case in point is
hard and soft tissue geometry of the patient’s intraoral condition that the predictable ability to isolate a subgingival margin for
to a computer program in the irst sequence. his is commonly adhesive cementation is a much more important factor to consider
referred to as a digital impression. A proprietary software design than whether the ceramic restoration is fabricated with a conven-
program is used to create a virtual restoration (the volume proposal) tional or digital impression technique. Nonetheless, there are a
in the second sequence. he software programs have the capability few speciic considerations relative to the use of digital impressions.
of controlling and editing the various parameters of the restoration he relative size of the camera may be a concern for patients with
such as emergence proile, proximal contact, and occlusal relation- a restricted ability to open wide. Generally, if there is suicient
ships. Once the proposal of the restoration has been completed, vertical space to complete the tooth preparation with a dental
a computer-controlled device is used to produce the restoration handpiece, there is suicient space for use of a digital camera.
in the third sequence. he most common device uses a subtractive However, patients with a severe gag relex may appreciate the use
process to machine (i.e., grind or mill, depending on whether of a digital impression more than conventional impression since
carbide burs or diamonds are used) the inal restoration from a there is no physical contact with the intraoral tissues by a tray or
preformed block of a variety of restorative materials. Understanding impression material when recording a digital impression.
these three sequences provides a basis for deciding how best to
implement the technology in the dental oice and also creates a Chairide CAD/CAM Sytem
simple way to categorize various systems in the marketplace.
Digital impression systems are designed to accurately record Dr. Francois Duret conceptualized the irst chairside CAD/CAM
the intraoral geometry and then transmit the iles to a dental labora- system in 1973. he irst functioning chairside CAD/CAM pro-
tory for design and fabrication of the desired restoration. here is totype was introduced in the 1980s through the collaboration
minimal if any opportunity for the dentist to design any aspect between a Swiss prosthodontist, Dr. Werner Mörmann, and an
of the restoration on digital impression systems. hey were developed Italian electrical engineer, Marco Brandestini. Dr. Mörmann’s vision
to leverage the digital recording process to take advantage of the was to use CAD/CAM technology to deliver esthetic ceramic
comfort and eiciency of not using conventional impression restorations with improved longevity in a single appointment that
materials as well as the convenience and accuracy of digital transmis- avoided the deleterious consequences polymerization shrinkage
sion of the case to the dental laboratory. caused in composite restorations.2,3 he CEREC 1 unit marked
Chairside CAD/CAM systems employ all three sequences of the introduction of the CEREC system in 1985 with the irst
the CAD/CAM process in the dental oice. hey also record clinical trials reported in 1987.4 he system has evolved through
intraoral scans but provide, in addition, a software program for a series of hardware and software innovations and upgrades that
designing restorations as well as milling units to fabricate the restora- culminated with the introduction of the irst color-streaming
tion during a single dental appointment. hey are designed to powder-free intraoral camera in 2012, the CEREC Omnicam (Fig.
leverage the eiciency of a single appointment procedure for the 12.1).5,6 he Omnicam is the imaging camera of the CEREC AC
delivery of ceramic restorations. Chairside CAD/CAM systems acquisition unit. he Omnicam is connected to a chairside computer
are the primary focus of the chapter because they allow the dentist with the three-dimensional design software and a liquid crystal
complete control of the design, fabrication, and delivery of the display (LCD) monitor. he CEREC system is electronically
restoration in the oice during a single appointment. connected to a milling unit. he newest version is a dry grinding

433
434 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

• Fig. 12.1 CEREC OmniCam and MCX milling chamber. (Courtesy Dentsply Sirona.)

• Fig. 12.2 PlanFit chairside CAD/CAM system. (Courtesy D4D Technologies.)

and wet milling unit that is the irst in-oice means by which to has an intraoral laser scanner, mobile Design Center with Denta-
dry mill zirconia. Single-visit, full-contour, milled zirconia restora- Logic software, and a separate milling unit with a dedicated CAM
tions are then further processed by sintering and glazing the restora- server computer. he milling unit has two opposing electric motors
tion in the CEREC SpeedFire sintering furnace. his is the irst that automatically change between three different diamonds
in-oice zirconia sintering furnace that can sinter preshaded CEREC depending on the speciics of the restoration dimensions. he
zirconia material (CEREC Zirconia) in 10 to 15 minutes, as milling unit has a dedicated computer server, which allows inde-
compared to the multiple hours that are generally necessary for pendent operation separate from the Design Center (after comple-
sintering laboratory processed zirconia restorations. tion and transmission of the case design) (Fig. 12.2).
An increasing number of chairside systems have been introduced The CS 3500 is a powder-free intraoral scanner that was
since the late 2000s. he E4D Dentist System (D4D Technologies) introduced in 2013. he Carestream system allows for in-oice
was introduced in 2008 with its DentaLogic software ofering a design using CS Solutions Restore software and in-oice fabrication
true three-dimensional virtual model.7 he E4D Dentist System using the CS 3000 milling unit. he digital iles may also be
 CHAPTER 12 Digital Dentitry in Operative Dentitry 435

uploaded to a dental laboratory via CS Connect as they are compat- A concept unique to CAD/CAM restorations has been termed
ible with a number of commercial laboratory design programs “undermilling” or “overmilling.” hese terms have been applied
such as 3Shape (3Shape) and Exocad (Exocad Gmbh). Some of to both grinding and milling processes. Any preparation geometry
the unique features of the intraoral scanner include a disposable smaller than the dimension of the milling instruments presents a
tip and a guiding light, which indicates a successful scan. he potential problem. Either the instrument must cut away more
Carestream system has chairside capability for only a limited number restorative material to ensure the restoration seats completely
of applications, including inlays, onlays, and crowns. (overmilling) or it does not remove the smaller geometry (undermill-
Chairside CAD/CAM systems are able to produce inlays, onlays, ing), leaving restorative material that will prevent complete seating
veneers, and crowns. Some systems also have the ability to fabricate of the restoration. Utilization of a preparation geometry with smooth
short-span ixed partial dentures as well as temporary restorations contours, gently lowing curves, and rounded transition angles
in the dental oice. Additional applications, such as implant helps to limit the potential for overmilling and ensure an accurate
abutments, ixed partial dentures, and orthodontic appliances, are internal adaptation of the restoration.
unique to speciic systems (Table 12.1).
Crown
Tooth Preparation Principle for Tooth preparation for CAD/CAM-fabricated crowns is essentially
CAD/CAM Retoration the same as for laboratory-fabricated ceramic crowns. he margin
design for an all-ceramic crown requires a bulk of ceramic at the
Guidelines for tooth preparation for all-ceramic restorations are margin to avoid the risk of ceramic chipping or fracture. his is
generally based on the speciic geometries and thickness dimensions best accomplished with a shoulder, sloped shoulder, or heavy chamfer
required to provide optimum strength for the selected ceramic margin (Fig. 12.3). All of these margin geometries are equally
material. For example, the occlusal reduction for a full-contour useful for chairside CAD/CAM crowns as long as the internal
zirconia crown is less than that required for a leucite-reinforced angles are rounded (i.e., not sharp or angular) to facilitate internal
or feldspathic porcelain crown, even if both materials are fabricated adaptation of the crown. he occlusal and axial reduction require-
with a chairside CAD/CAM system. However, there are several ments are determined based on the speciic material properties of
preparation guidelines that enhance the accuracy of the CAD/ the ceramic material selected for the crown. Axial reduction for
CAM restoration due to their inluence on the imaging and fabrica- CAD/CAM ceramic crowns should be 1 to 1.2 mm for the
tion process, such as smooth contours, rounded transitions, and monolithic ceramic materials as there is no opaque inner coping
uniform pulpal loor. that needs to be covered (veneered). A greater variation in occlusal

TABLE 12.1 Clinical Applications for Chairside CAD/CAM Systems

System Inlays/Onlays Crowns Veneers FPDs Implant Abutment Orthodontic Application CBCT Compatible
CEREC (Dentsply Sirona)
BlueCam X X X X X X X
OmniCam X X X X X X X
PlanFit (Planmeca) X X X X – – X
CS Solutions (Carestream) X X X – – – X

A B
• Fig. 12.3 A and B, Examples of chairside CAD/CAM crown preparations.
436 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

A
• Fig. 12.5 Onlay preparations for teeth #3 and #4 relying primarily on
the adhesive bond of the resin cement for retention of the restoration.

B
• Fig. 12.4A and B, Examples of the occlusal clearance for chairside
CAD/CAM crown preparations.

• Fig. 12.6 Full cuspal onlay preparation for tooth #3 and MODL onlay
for #4 with smooth and rounded internal angles.
reduction may be expected as a function of the material selected.
Most glass ceramic materials require a minimum of 1.5 mm occlusal
reduction in the central issure area and over nonfunctional cusps Inlay and Onlay
and 2 mm over functional cusps (Fig. 12.4). Laboratory-based (in
vitro) research studies suggest that full-contour zirconia crowns CAD/CAM inlay and onlay preparations are primarily adhesive-style
may be fabricated with an occlusal thickness of 1 mm without preparations that rely on the adhesion of the resin cement to dentin
compromising the strength of the crown. Additionally, the manu- and enamel for retention of the restoration (Fig. 12.5). hese
facturer of lithium disilicate blocks has recently announced that preparations are divergent and relatively nonmechanically retentive
e.maxCAD crowns now only require a 1-mm occlusal reduction; in design as this provides a more conservative preparation than
however, this claim still requires independent validation. All angles the requirement for mechanical resistance through grooves, slots,
of the preparation should be rounded to facilitate accurate internal or boxes. he internal aspect of the preparation should avoid sharp
adaptation and needless overcutting of the internal surface of the divots or concavities, and all internal angles should be rounded
crowns during milling. (Fig. 12.6). Occlusal reduction should be uniform and of suicient
It is not uncommon to identify signiicant undercuts in a crown thickness to provide optimum strength of the selected ceramic
preparation as a result of prior large restorations or caries excavation. material similar to crown preparations. Preparation should allow
Undercuts will be accurately recorded by the digital camera and for a minimum of 1.5 mm of ceramic thickness in the central
be present in the calculated virtual model in the CAD software fossa and over nonfunctional cusps, and 2 mm over functional
program. However, the milling process will not duplicate any cusps. All cavosurface margins should be strategically placed away
internal undercuts in the preparation that might prevent seating from the contact position of the opposing cusp(s) and be well
of the restoration. hese undercuts would subsequently be illed deined (smooth) for easy identiication in the design software.
in with the resin cement. Alternatively, undercuts could be blocked Beveled margins must be avoided, as thin areas of ceramic are
out using the software program during design of the restoration. prone to fracture.8,9 Similarly, the preparation isthmus should be
his process is not recommended, however, as it could ultimately at least 2 mm in faciolingual width so as to avoid inlay/onlay
result in an internal inaccuracy as the digital model is altered. fracture (Fig. 12.7).
herefore, if blockout is necessary, it is best accomplished with an CAD/CAM onlay preparations do not require the creation of
appropriate dentin substitute material, as indicated, prior to digital a ferrule with the ceramic restoration as used with metal castings
scanning. (Fig. 12.8). On the contrary, a ferrule may actually interfere with
 CHAPTER 12 Digital Dentitry in Operative Dentitry 437

• Fig. 12.10 Modiied butt-joint margin with a football-shaped diamond

for improved esthetic blending of the onlay margin.
• Fig. 12.7 Inlay preparation for tooth #13 and onlay preparation for
tooth #14 with smooth lowing outline form and crisp cavosurface margins.
of esthetic concern, a modiication of the facial butt-joint margin
is necessary. he cavosurface margin may be modiied with a
football-shaped diamond at a 45-degree angle, creating opportunity
for a transition of ceramic thickness over the underlying enamel
while maintaining a bulk of ceramic at the margin for physical
strength of the ceramic (Fig. 12.10). An in vitro study on ceramic
preparations for conservative restoration of endodontically treated
teeth reported a signiicant improvement in the marginal and
internal it of the ceramic restoration with this modiied-margin
design relative to both a ferrule and 90-degree butt-joint margin.10

Chairide CAD/CAM Clinical Worklow

he clinical worklow to design and fabricate a chairside CAD/
• Fig. 12.8 Ferrule margin design with opposing walls for mechanical CAM restoration is relatively similar for all currently available
retention more appropriate for cast-metal restorations. systems, with noticeable diferences in the unique cameras, software
programs, and milling chambers of marketed systems (Fig. 12.11A–L
worklow sequence). he tooth preparation, including the margins,
must be visible by retraction of soft tissues and isolated from
moisture contamination so that the camera may accurately capture
a digital image of the preparation. he opposing arch is also
recorded, as well as a scan of the dentition in maximum intercuspa-
tion from the facial aspect. The computer software virtually
articulates the opposing models using the scan of the facial surfaces
so the appropriate occlusal relationships for the restoration may
be designed. he restoration design is initiated by identifying the
margins of the planned restoration to identify the limits of the
restoration design. he software utilizes data from adjacent and
opposing teeth to generate a proposed (virtual) restoration, which
may then be edited by a series of tools unique to each software
program. he design software enables control of the emergence
• Fig. 12.9 Preferred butt-joint margin design for ceramic onlay proile of the restoration, occlusal anatomy, planned occlusal
preparation. contacts, and size and intensity of proximal contacts. Once the
design of the restoration is complete, it is transmitted to the milling
unit so the fabrication process may create the volumetric shape of
proper seating of the restoration due to undermilling of the relatively the restoration out of an industrially produced block of ceramic
parallel walls and/or sharp transitions. Alternatively the system material. Although a variety of chairside fabrication processes may
may signiicantly overmill the intaglio surface of the restoration, be imagined, subtractive grinding or milling processes of ceramic
thinning the restoration further. Both undermilling and overmilling blocks are accomplished based on the volumetric design created
are detrimental to the inal onlay restoration. Consequently, a with the software design program. Most restorations may be designed
butt-joint margin is preferred as it allows for proper thickness of and milled within 10 to 15 minutes to allow for delivery of the
the ceramic material at the margin, reducing the incidence of restoration at the same appointment. Extended machining times
marginal fracture (Fig. 12.9). Unfortunately, this marginal design may be required for more complex geometries of ixed partial
often causes a visible demarcation between the tooth and the restora- dentures or implant restorations. Slower machining may be preferred
tion. Hence, when the blend of the restoration and the tooth is for thin margins, such as for porcelain veneers, in order to prevent
438 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

chipping during fabrication. Certain systems allow for ine machin- ceramic restoration will then have very good adaptation to the
ing modes, which slow the advancement of the block at each pass existing RPD. he copy-design process is also very useful for anterior
of the diamonds/burs (or allow for a smoother second machining restorations through use of a diagnostic wax-up containing strategi-
pass), so as to reine the surface contour. Final glaze iring and/or cally planned contours of the restorations. hese contours may be
external surface polishing follows clinical conirmation of the virtually copied onto the recorded preparation, digitally perfected,
anatomy and marginal adaptation of the resultant restoration. he and then transmitted for milling.
inal restoration is adhesively cemented with resin cement.
Chairside CAD/CAM software programs also ofer various Chairide Retorative Material
design techniques that provide the opportunity to copy a pretreat-
ment or prototype tooth form onto the recorded tooth preparation. Dental material manufacturers produce monolithic materials for
he copy function minimizes the need for restoration editing chairside CAD/CAM restorations generally referred to as “blocks.”
following the proposal of the restoration, which is especially useful he blocks are dense, homogeneous materials that have been
in clinical situations requiring the restoration of fractured abutment industrially produced under ideal conditions so as to limit the
teeth for removable partial dentures (RPD). Existing rest seat and presence of internal laws (porosity or voids). Limited inclusion
proximal contours are copied from the pretreatment tooth and of laws enables maximization of the physical properties of the
subsequently applied to the recorded tooth preparation. he new Text continued on p. 443

A B

C
• Fig. 12.11 Chairside CAD/CAM worklow using the CEREC system. A, Preoperative view of tooth
#19. B, All-ceramic crown preparation for tooth #19. C, Case identiication in the Administrative Phase.
 CHAPTER 12 Digital Dentitry in Operative Dentitry 439

E
• Fig. 12.11, cont’d D, Intraoral digital scan of the mandibular left quadrant. E, Virtual mounting of the
opposing digital models. Continued
440 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

G
• Fig. 12.11, cont’d F, The Model Axis is set for the model. G, The crown margin is identiied.
 CHAPTER 12 Digital Dentitry in Operative Dentitry 441

I
• Fig. 12.11, cont’d H, Biogeneric proposal of the crown. I, Visualization of the occlusal contacts for
reinement. Continued
442 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

K
• Fig. 12.11, cont’d J, Visualization of the proximal contact for reinement. K, Crown proposal in the
proposed mill block (Celtra Duo).
 CHAPTER 12 Digital Dentitry in Operative Dentitry 443

L
• Fig. 12.11, cont’d L, Delivered Celtra Duo ceramic crown for tooth #19. (C–K, Courtesy Dentsply
Sirona.)

TABLE 12.2 Restorative Material Options for Chairside CAD/CAM Systems

Material Brand CEREC PlanFit CS Solution
Adhesive ceramic
Leucite-reinforced IPS EmpressCAD (Ivoclar) X X –
Feldspathic Vita Mark II (Vita) X X X
Sirona Blocs (Dentsply Sirona) X – –
High-strength ceramic
Lithium disilicate IPS emaxCAD (Ivoclar) X X –
Zirconia-reinforced lithium-silicate Celtra Duo (Dentsply Sirona) X – –
Lithium-silicate Obsidian (Glidewell) – X –
Resilient ceramic (resin nano ceramic) Lava Ultimate (3M) X X X
Enamic (Vita) X X X
Cerasmart (GC America) X – –
Composite resin Paradigm MZ100 (3M) X – –
Brilliant Crios (Coltene) X – –
Zirconia (full contour) CEREC Zirconia (Dentsply Sirona) X – –
Provisional acrylic materials TelioCAD (Ivoclar) X X –
Vita CAD-Temp (Vita) X – –

material. he blocks are attached to mandrels that are speciic to 4. Composite materials that have a resin matrix
the various brands of chairside CAD/CAM milling units. 5. Full-contour zirconia that may be cemented to the tooth
he irst CAD/CAM block was created as a result of the col- 6. Provisional materials used for temporary restorations
laboration between Dr. Werner Mörmann and the Vita Corporation. The adhesive ceramic category includes both fine-grained
he Vita Mark I blocks were originally created out of feldspathic feldspathic porcelain and leucite-reinforced porcelain. hese materi-
porcelain and eventually evolved into the current generation of als contain a signiicant glass component resulting in increased
feldspathic blocks, Vita Mark II. Since then the CAD/CAM market translucency allowing them to have an improved “chameleon”
has expanded to include multiple formulations of ceramic efect. he chameleon efect may be described as the ability to
materials. relect the color of the surrounding tooth structure and thus blend
Chairside CAD/CAM materials may be divided among a number into the existing tooth shade (Fig. 12.12). hese materials have a
of categories based on material composition for ease in understand- moderate lexural strength on the order of 100 to 175 megapascals
ing their properties and clinical applications.11,12 hese categories (MPa). he glass component of these materials allows them to be
include (Table 12.2): etched with hydroluoric acid for micromechanical adhesive bonding.
1. Adhesive ceramics (feldspathic, leucite-reinforced) that must Adhesive bonding is critical to their long-term success because the
be etched and adhesively bonded to the tooth structure glass matrix makes them brittle. hese materials do not have enough
2. High-strength ceramics (lithium disilicate, zirconia reinforced inherent physical strength to be cemented with resin-modiied
lithium silicate) with improved strength properties compared glass ionomer or traditional glass ionomer cements. he adhesive
to the adhesive ceramic materials resin cement not only provides retention for the restoration but,
3. Resilient ceramics that do not require a porcelain furnace and by virtue of its adhesive properties, contributes to the physical
must be adhesively bonded to the tooth strength of the ceramic to resist fracture by limiting lexure under
444 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

A B

C D
• Fig. 12.12 Vita Mark II (Vita) onlay for tooth #30. A, Preoperative view of tooth #30. B, Vita Mark II
onlay delivered. C, Vita mark II onlay at the 3-year recall. D, Vita mark II onlay at the 5-year recall.

occlusal load. Vita Mark II (Vita) and Sirona Blocks (Dentsply iring also creates optimum translucency for the material (Fig.
Sirona) are both feldspathic porcelain blocks with a ine-grained 12.14). Celtra Duo (Dentsply Sirona) is a zirconia-reinforced lithium
particle size that averages 4 microns and a lexural strength of silicate (ZLS) material that is another example of ceramic with high
100 MPa.13,14 strength. he ZLS microstructure has high content of ultraine
he leucite-reinforced glass ceramic was initially introduced glass ceramic crystals (<1 µm) and 10% zirconia content. It is
as ProCAD (Ivoclar) and later evolved into IPS EmpressCAD provided by the manufacturer in a fully crystallized state that may
(Ivoclar) with a similar crystal structure as IPS Empress 1 (Ivoclar). be either hand polished or glaze ired in a ceramic furnace prior to
EmpressCAD has a iner particle size of 1 to 5 microns that is delivery. Hand polishing the restoration results in a material that
evenly dispersed 35% to 45% by volume using a proprietary has a lexural strength of 210 MPa, while glazing it in a porcelain
manufacturing process. It comes in two levels of translucency as oven results in a restoration with a lexural strength of 370 MPa.
well as multishaded blocks.13 he manufacturer-reported lexural Celtra Duo is available in shades A1, A2, A3, A3.5, and B2 in
strength is 160 MPa, which is within the range of what is reported both high and low translucencies (Fig. 12.15). NICE! (Straumann)
independently in the literature. EmpressCAD also has a light is another fully crystallized zirconia-reinforced lithium silicate
scattering behavior that allows for a natural chameleon efect block that has recently been introduced for chairside CAD/CAM
(Fig. 12.13). restorations.
here are several higher strength glass ceramic materials available he Resilient Ceramic category of chairside CAD/CAM blocks
for chairside CAD/CAM restorations. IPS e.maxCAD (Ivoclar) [Lava Ultimate (3M), Enamic (Vita), and Cerasmart (GC America)]
is composed of lithium disilicate and has a signiicantly greater includes materials that have a resin matrix (instead of a glass matrix)
lexural strength and fracture toughness than other adhesive glass that, according to manufacturers, allows greater force absorption
ceramics.15,16 he manufacturer provides the IPS e.maxCAD block in capability without fracture. he added feature of these materials
a partially crystallized state (160 MPa, 40% crystalized by volume) to is that no additional iring is required allowing for a very eicient
allow for easier and more eicient grinding of the material. After the delivery process following fabrication of the restoration. All three
restoration has been fabricated, it must be subjected to a two-stage materials (Lava Ultimate, Cerasmart, and Enamic) exhibit lexural
iring cycle in a ceramic furnace under vacuum to complete the strength properties similar to human dentin, and are indicated for
crystallization process and achieve the maximum lexural strength single-unit restorations. In contrast, the low stifness properties of
potential of the material (500 MPa). he resulting glass ceramic these materials may be considered disadvantageous from a bonding
restoration has a grain size of approximately 1.5 microns with a 70% perspective, as marginal seal debonding due to material lexure
crystal volume incorporated in a glass matrix. he crystallization might occur.17 Therefore treating the intaglio surface of the
 CHAPTER 12 Digital Dentitry in Operative Dentitry 445

A B

• Fig. 12.13 IPS EmpressCAD (Ivoclar) restoration. A, Onlay

preparation for tooth #19. B, IPS EmpressCAD onlay delivered. C,
C
IPS EmpressCAD onlay at the 2-year recall.

A B

C D
• Fig. 12.14 IPS emaxCAD (Ivoclar) crown for tooth #30. A, Preoperative view of tooth #30. B, IPS
emaxCAD crown delivered. C, IPS emaxCAD crown at 2-year recall. D, IPS emaxCAD crown at 4-year
recall.
446 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

A B

C D
• Fig. 12.15 Glazed Celtra Duo (Dentsply Sirona) crown for teeth #4 and #5. A, All-ceramic crown
preparations for teeth #4 and #5. B, Facial view of all-ceramic crown preparations from the facial. C,
Delivered glazed Celtra Duo crowns for teeth #4 and #5. D, Facial view of delivered Celtra Duo glazed
crowns.

restoration with sandblasting technique as well as selecting a total- improving the fracture resistance of the material due to its capability
etch approach combined with adhesive cementation is considered of undergoing plastic deformation.20 he manufacturer recommends
to be imperative. Because resilient ceramics are less dense they the material for inlays, onlays, and crowns and reports that lexural
mill faster, with a smaller incidence of margin chipping during strength of Enamic is 150 MPa, which is signiicantly lower than
milling compared to glass-containing materials.17 Lava Ultimate or Cerasmart. his is in line with the results of an
Lava Ultimate (3M) is a nanoceramic material that contains independent study (approximately 135 ± 25 MPa).17
20 nanometers (nm) size silica particles, 4 to 11 nm size zirconia Composite resin block materials are gaining in interest as the
particles, and agglomerated nanosize particles of silica and zirconia, eiciency of chairside designing and milling a CAD/CAM restora-
all embedded in a highly cross-linked polymer matrix with an tion has improved. he chairside CAD/CAM worklow allows for
approximately 80% ceramic load. Lava Ultimate has a reported easier control of proximal contours, contacts, and occlusal relation-
lexural strength of 170 MPa and it is indicated for inlays and ships for larger, more complex multisurface composite restorations
onlays but not for crowns (Fig. 12.16).17,18 compared to incremental hand placement of direct composite
Cerasmart (GC America) is described by the manufacturer as materials. Paradigm MZ100 (3M) is a composite block based on
a lexible nanoceramic with a resin matrix containing homoge- Z100 composite chemistry and relies on a proprietary processing
neously distributed nanoceramic iller particles. he material is technique to maximize the degree of cross-linking in the bis-GMA
a high-density composite resin with 71% silica and barium glass polymer-based composite material. It has zirconia-silica iller, which
nanoparticles iller by weight.17 he reported lexural strength is radiopaque, and is 85% illed by weight with an average particle
of Cerasmart is 230 MPa and it is indicated for inlays, onlays, size of 0.6 micron.21 he manufacturer reported lexural strength
and crowns.17 of Paradigm MZ100 is 150 MPa. An independent study reported
Enamic (Vita) is described by the manufacturer as a resin-based slightly higher value 157 ± 30 MPa, which was not signiicantly
(14 wt%) hybrid ceramic comprised of a dual interpenetrating diferent than the lexural strength reported for EmpressCAD.17
structure of a leucite-based and zirconia-reinforced ceramic network Brilliant Crios (Coltene) is a recently introduced reinforced
(86 wt%). he mechanical properties of the material are in between composite block containing amorphous silica and glass ceramic
glass ceramics and highly illed composites.19 he ceramic network particles in a cross-linked methacrylate matrix.
provides wear resistance; however, it makes the material more brittle he most recent material innovation for chairside CAD/CAM
and susceptible to fracture. he polymer network is capable of restorations was the introduction, in 2016, of CEREC Zirconia
 CHAPTER 12 Digital Dentitry in Operative Dentitry 447

900 MPa; therefore it is suitable for crowns as well as short-span

ixed partial dentures (FPDs) that may be cemented with traditional
cements.
A unique property of zirconia is that it shrinks volumetrically
approximately 22% to 24% when sintered. he CEREC software
program automatically compensates for the degree of shrinkage
in the milled restoration. When the restoration design is ready for
milling, the bar code on the zirconia block is input into the software
program. he bar code contains the precise amount of expected
shrinkage of the particular zirconia block as determined by the
manufacturer. he software virtually expands the designed restoration
by this degree and an enlarged restoration is milled. he CEREC
software automatically programs the SpeedFire furnace to sinter
the milled zirconia restoration and iring shrinkage results in a
inal restoration that accurately its the preparation. he sintering
A
process takes 10 to 15 minutes for crowns and more than 25
minutes for FPDs. Subsequent glaze iring and surface color
characterization is optional. Glazing of the zirconia restoration
may be accomplished in the SpeedFire furnace or in a conventional
porcelain furnace.
CAD/CAM blocks for provisional restorations are also avail-
able for chairside fabrication of long-term provisional crowns and
FPDs. he chairside CAD/CAM process avoids the air-inhibited
layer present on conventional self-cure or VLC acrylics as well as
polymerization shrinkage. Vita CAD-Temp blocks (Vita) are made
from a highly cross-linked, microilled polymer and are available
in extended block sizes, including 40 mm and 55 mm lengths, to
accommodate multiple unit FPDs. Telio CAD (Ivoclar) is a millable
cross-linked polymethyl methacrylate block that is part of the Telio
System (a self-curing composite, desensitizer, and cement). he
Telio CAD material is also available in 40 mm and 55 mm size
B
blocks.

Accuracy of Digital Impreion

It is axiomatic that the accuracy of the inal restoration depends
on the accuracy of the recorded dimensions of the tooth preparation.
his is true for both conventional and digital impressions. he
accuracy of the margin it and internal adaptation of any restoration
is limited by the geometry of the tooth preparation and the limita-
tions of the recording medium. he tooth preparation must be
well isolated from moisture contamination and adjacent soft tissues
if an accurate digital impression is to be made.
Current technology will not allow the digital capture of
the tooth preparation through saliva, blood, or soft tissue.
A simple way to think about digital impressions is that the
C camera can only accurately record what is clearly visible to the
eye of the operator. Careful control of the scanning environ-
• Fig. 12.16 Lava Ultimate (3M) onlay for tooth #14. A, Onlay prepara- ment ensures an accurate surface reproduction with the digital
tion for tooth #14. B, Lava ultimate onlay delivered for tooth #14. C, Lava impression.
Ultimate onlay at the 3-year recall. Conventional impression materials require lateral and cervical
retraction of the soft tissues for an accurate impression. Lateral
space must be adequate to ensure suicient impression material
to resist tearing at the margin. Cervical space, generally 1 mm
(Dentsply Sirona). his material is a precolored, full-contour cervical to the margin, is required for accurate assessment of the
zirconia that may be processed eiciently for a single-appointment recorded margin in the impression. Digital impressions have the
delivery. he fast production time is a result of the simultaneous advantage that soft tissues only need be retracted laterally in order
introduction of the SpeedFire (Dentsply Sirona) furnace that is able to visualize the margin.
to sinter the zirconia restorations in under 20 minutes. Zirconia Digital impressions provide excellent immediate feedback relative
has a lexural strength and fracture toughness that is generally to the recorded tooth preparation. Digital magniication of the
at least three times as great as glass ceramic materials.22 CEREC image, in many cases up to 20 times lifesize, facilitates critical
zirconia has a manufacturer reported lexural strength of over evaluation of the tooth preparation while the patient is still in the
448 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

chair. Preparation corrections may be accomplished immediately. higher than that of the other methods (P < 0.05). he mean
Additionally, inadequately captured areas may be immediately internal it was 29 ± 7 µm for Lava COS, 88 ± 20 µm for CEREC
reimaged without the need to redo the entire impression, as is the AC, 50 ± 2 µm for iTero, 36 ± 5 µm for single-step putty-wash
case with conventional impression materials. technique, and 35 ± 7 µm for two-step putty-wash technique.
here was no signiicant diference in the mean internal it for all
groups (P > 0.05) except the CEREC AC (P < 0.05).
Reearch Relative to CAD/CAM Sytem Another study compared the it of Lava DVS zirconia crowns
fabricated using Lava COS digital impressions to Vita Rapid
Dentists have ongoing concern that restoration adaptation to tooth Layering Technique crowns using digital impressions with the
preparations allows for optimal clinical performance. he CEREC CEREC AC system.25 Two posterior crowns were fabricated for
system was the initial chairside CAD/CAM system introduced to each of 14 patients using each digital impression technique on the
the dental marketplace and has over 30 years of both laboratory same tooth preparation. he replica technique was used with all
and clinical research documenting the relative accuracy of the it crowns to measure the clinical adaptation and margin it. he
of CEREC chairside CAD/CAM restorations. Digital camera study reported that crowns made with the Lava COS system had
technology has evolved from a single image capture process a statistically signiicant better mean marginal it (51 ± 38 µm)
(RedCam) to the LED-based BlueCam to the present video version when compared to crowns fabricated using the CEREC system
(OmniCam). he it of CEREC restorations have consistently (83 ± 51 µm); however, this diference in it was below the accepted
been considered accurate irrespective to the version of the image clinical threshold of 100 µm and therefore it may not be clinically
capturing device used. Cook and Fasbinder compared marginal relevant.
it and internal adaptation of crowns fabricated on virtual models Lee et al. investigated the margin it of ceramic crowns from
made from the CEREC 3 infrared laser camera (RedCam) and two diferent digital impression systems and the CEREC chairside
CEREC BlueCam.10 No signiicant diference was found in the CAD/CAM system.26 Crowns were fabricated from digital impres-
margin it and internal adaptation of CEREC crowns fabricated sions using the Lava COS and Cercon systems and from digital
with either RedCam or BlueCam. he average marginal gap was impressions using the CEREC BlueCam and compared to PFM
67 ± 18 µm for all groups evaluated. crowns made with a conventional impression technique. he mean
Marginal adaptation (or margin it) plays a critical role in marginal gaps were 70.5 ± 34.4 µm for the PFM crowns, 87.2 ±
long-term clinical performance of CAD/CAM restorations; when 22.8 µm for Lava, 58.5 ± 17.6 µm for Cercon, and 72.3 ± 30.8 µm
the adaptation of the restoration to the preparation is poor it leads for CEREC BlueCam. here were no signiicant diferences in the
to greater discrepancies at the margin. Restoration adaptation has marginal it among most of the groups except that Cercon crowns
been thoroughly investigated in the literature. Whereas some internal presented signiicantly smaller marginal gaps than Lava crowns (P
space is necessary to accommodate the resin cement, most authors < 0.001). However, once again this diference in it was below the
are in agreement that margin openings under 100 µm would be accepted clinical threshold of 100 µm and therefore may not be
desirable. A systematic review evaluated the it and margin adapta- clinically relevant.
tion of CAD/CAM restorations.23 Two electronic databases were Another study investigated diferent chairside CAD/CAM
searched for articles published between 2000 and 2012 and systems relative to margin it of ceramic crowns.27 hree lithium
cross-matched against predetermined inclusion and exclusion criteria. disilicate crown fabrication techniques were included: CEREC 3D
A total of 230 studies were reviewed and 90 were selected for the BlueCam, E4D laser scanner, and a lost-wax, heat-pressed technique
meta-analysis, including data on 26 diferent CAD/CAM systems. (IPS Empress 1). Microcomputed tomography was used to measure
he authors concluded that restorations fabricated using CAD/ margin discrepancies on the crowns. Heat-pressed crowns had a
CAM systems have better internal it than restorations fabricated mean vertical misit of 36.8 ± 13.9 µm and CEREC crowns had
using traditional methods. he marginal gap of crowns, made mean vertical misit of 39.2 ± 8.7 µm, both of which were statisti-
from a variety of primarily ceramic materials, ranged from 10 to cally signiicantly smaller than the mean vertical misit recorded
110 µm, often with gaps less than 80 µm. It was reported that for the E4D crowns, 66.9 ± 31.9 µm (P < 0.05). In addition, the
the limitation of CAD/CAM systems is not achieving a precise authors suggested that clinically acceptable it should be equal or
margin it, but the reliability of doing so over a large set of less than 75 µm. he percentage of crowns with a vertical misit
restorations. under the 75 µm reported was 83.8% for CEREC and heat-pressed
Margin it is also an indicator of accuracy of restorations. An technique, whereas only 65% of the E4D crowns had vertical
in vitro study by Seelbach et al. compared the accuracy of ceramic misit under that value, potentially indicating better it accuracy
crowns fabricated from scans using Lava COS, CEREC AC, and for CEREC and heat-pressed technique.
iTero digital impressions with two diferent conventional impression Ender and Mehl evaluated the in vivo precision of impressions
techniques.24 A stainless steel master model was scanned 10 times using conventional and digital methods.28 he conventional methods
each with the Lava COS and iTero (Cadent) systems, and zirconia used were metal full-arch tray or triple tray with PVS material. In
crowns were made from each digital impression. he master model addition, eight digital impression systems were also evaluated: Lava
was scanned 10 times with the CEREC AC (BlueCam) system True Deinition Scanner and Lava COS (3M ESPE), iTero (Cadent),
and 10 EmpressCAD crowns were fabricated. Ten putty-wash Trios (3Shape), Trios Color (3Shape), as well as CEREC BlueCam
impressions using a single step and a two-step technique were (Software 4.0), CEREC BlueCam (Software 4.2), and CEREC
made and zirconia crowns were made from each impression. here Omnicam (Dentsply Sirona). Five subjects each received three
was no statistically signiicant diference in the marginal it of the quadrant impressions with each of the impression methods. he
crowns fabricated using Lava COS (48 ± 25 µm), CEREC AC impressions were superimposed within each test impression group,
(30 ± 17 µm), iTero (41 ± 16 µm), and the single-step putty-wash for each patient, using CAD software (Geomagic Qualify 12, 3D
technique (33 ± 19 µm), whereas the mean margin it for the Systems). A perfect match (misit of zero) would indicate ideal
two-step putty-wash technique (60 ± 30 µm) was signiicantly precision, with increasing values from zero gradually indicating
 CHAPTER 12 Digital Dentitry in Operative Dentitry 449

poorer precision. he precision for all methods ranged from 18.8 by using both a replica technique and visual examination looking
± 7.1 µm for the metal full-arch tray to 58.5 ± 22.8 µm with the at common criteria for ceramic restorations. he quality of the
triple tray. he conventional metal full-arch tray had statistically preparation inluenced the accuracy of the margin it in ways that
best precision of all groups, followed by True Def (21.7 ± 7.4 µm), were statistically signiicant. Ideal preparations had a mean margin
Trios (25.7 ± 4.9 µm), Trios Color (26.1 ± 3.8 µm), and group it of 38.5 ± 9 µm, fair preparations had 58.3 ± 12 µm, and poor
BlueCam 4.0 (34.2 ± 10.5 µm). No statistically signiicant diference preparations had 90.1 ± 23 µm. A second in vitro study measured
was found between BlueCam 4.2 (43.3 ± 19.6 µm), OmniCam the margin it and internal adaptation of E4D fabricated emaxCAD
(37.4 ± 8.1 µm), Lava COS (47.7 ± 16.1 µm), iTero (49 ± crowns.32 Mean margin its varied from 79.32 ± 63.18 µm for
12.4 µm), and conventional triple tray impressions (58.5 ± buccal margins to 50.39 ± 35.98 µm for lingual margins. Additional
22.8 µm). he authors concluded that despite signiicant diferences independent studies are warranted for a more precise assessment
found, all of the digital impression systems were capable of produc- of margin it and internal adaptation of PlanFit and CS Solutions
ing quadrant impression with precision that was clinically restorations.
acceptable.
Hack and Patzalt measured the ability of six intraoral scanners Clinical Longevity of CAD/CAM Retoration
to accurately capture a single molar abutment tooth in vitro.29 he
scanners tested included iTero, True Def, PlanScan, CS 3500, he clinical performance of chairside CAD/CAM restorations has
Trios, and CEREC Omnicam. A master typodont model of a been studied so as to assess relative longevity in the oral environment.
single crown preparation was scanned with a highly accurate Long-term randomized clinical trials are considered the most robust
industrial benchtop scanner, and the digital ile from the benchtop study design for the purpose of proper assessment of clinical longev-
scanner was compared to the digital scans of the intraoral scanners ity. However, there is considerable amount of variation in the
using a CAD software program (Geomagic Qualify). Precision dental literature when searching for independent randomized studies
was measured by superimposing the benchtop scanner digital ile on clinical longevity of chairside CAD/CAM restorations. he
onto the digital iles recorded by each scanner and evaluated for vast majority of the publications report on the long-term clinical
three-dimensional deviations. Similar to a previously mentioned performance of CEREC restorations primarily because the CEREC
study, a perfect match (misit of zero) would indicate ideal precision, System has been available since the early 1990s whereas other
with increasing values from zero gradually indicating poorer preci- systems have been more recently introduced. Systematic reviews
sion. he authors reported most accurate precision values for the represent invaluable tools to synthesize the results of these multiple
Trios (4.5 ± 0.9 µm), followed by True Def (6.1 ± 1 µm), iTero and varied clinical studies; however, the conclusions of systematic
(7 ± 1.4 µm), CS3500 (7.2 ± 1.7 µm), CEREC OmniCam (16.2 reviews are only as valuable as the quality of the studies they seek
± 4 µm), and PlanScan (26.4 ± 5 µm). Statistically signiicant to combine.
differences were reported between all scanners and CEREC Wittneben and coworkers evaluated the clinical performance
Omnicam (P < 0.05) as well as between all scanners and PlanScan of CAD/CAM restorations in a systematic review.33 he authors
(P < 0.05). he authors concluded that, even though there were performed an electronic search of all publications on clinical
diferences in levels of accuracy, all scanners investigated produced performance of CAD/CAM restoration between 1985 and 2007.
clinically acceptable accuracy. Studies were selected following speciic inclusion criteria. he
A more recent systematic review also evaluated the marginal included publications comprised 14 prospective and 2 retrospective
it of single-unit all-ceramic crowns fabricated after conventional studies on the chairside CEREC System (CEREC 1 and 2) as well
and digital impressions. he search included studies published as the laboratory system Celay, providing follow-up data from 2
from January 1989 through December 2014. From the original to 10 years. he search yielded data on a total of 1957 restorations
63 articles that were identiied, 12 were selected (both in vitro and with a mean exposure time of 7.9 years. he restorations included
in vivo) after applying the inclusion and exclusion criteria. For in mostly posterior crowns, but some studies evaluated inlays, onlays,
vitro studies mean marginal it of crowns fabricated after conven- endocrowns, and anterior crowns. A total of 170 failures were
tional impressions was 58.9 µm (95% CI: 41.1–76.7 µm), whereas reported, at a rate of 1.75% failure per year. he most common
for digital impressions it was 63.3 µm (95% CI: 50.5–76 µm). modes of failure described were fractures of the restoration or
However, for in vivo studies the results were reversed with mean tooth. he estimated survival rate for CEREC single-tooth restora-
marginal it of crowns fabricated after digital impressions 56.1 µm tions was 91.6% (95% CI: 1.22%–2.52%). Restorations fabricated
(95% CI: 46.3–65.8 µm), whereas for digital impressions it was with feldspathic porcelain had the highest 5-year survival rate,
79.2 µm (95% CI: 59.6–98.9 µm). he authors reported low which contrasted with the lowest 5-year survival rate for glass
overall risk of bias of the included studies as well as moderate ceramic. At 5 years, ceramic onlays performed equally as successful
heterogeneity, mostly due to the variety of intraoral scanners and as crowns; however, the authors identiied a signiicant lack of
ceramic materials in the studies included. he result of the meta- randomized studies as well as a shortage of scientiic evidence
analysis indicated no statistically signiicant diference in marginal longer than 3 years.
gap of single-unit ceramic restorations fabricated after conventional Among the CEREC literature, several of the studies published
or digital impressions. he authors suggested that the digital data on CAD/CAM generated feldspathic porcelain restorations.
worklow exceeds clinically acceptable standards and performs equal Posselt and Kerschbaum conducted a retrospective study on the
to conventional impressions.30 clinical performance of 2328 inlays and onlays for 794 patients
he PlanFit and CS Solutions systems have been more recently in a private practice setting. A total of 35 failures were reported
introduced for chairside CAD/CAM restorations and have very over 9 years. he Kaplan-Meier survival probability reported was
limited published research on margin it and internal adaptation. 97.4% at 5 years and 95.5% at 9 years for CEREC inlays and
One study measured the marginal it of E4D fabricated crowns onlays. According to the authors, failure rate was not signiicantly
on typodont preparations completed by 62 diferent clinicians.31 inluenced by restoration size, tooth vitality, previous presence of
Each of the crown preparations was judged as good, fair, or poor deep caries, type of tooth treated, or whether the restoration was
450 C HA P T E R 1 2 Digital Dentitry in Operative Dentitry

located in the maxilla or mandible. he most common type of in margin adaptation was noted when inlays of both materials were
failure reported was tooth extraction.34 A 10-year prospective clinical compared to baseline values due to margin wear of the adhesive
trial on feldspathic CEREC 1 inlays and onlays reported a Kaplan- luting cement over time. Composite inlays had fewer fractures
Meier survival probability of 90.4% after 10 years for 200 restora- in 10 years, with a calculated survival rate of 95% for Paradigm
tions placed in private practice. he restorations were placed in MZ100 inlays versus 87.5% for Vitablocks Mark II. he calculated
108 patients (62 female, 46 male). he mean age of the patients annual failure rates were 0.5% for composite inlays and 1.25% for
was 37 years (range 17 to 75 years). All patients presented with ceramic inlays.39
good dental care and a low risk for caries. he restorations were he vast majority of publications report on feldspathic CAD/
fabricated chairside using Vita MK I feldspathic ceramic and were CAM materials because they were the irst blocks available for
delivered with adhesive technique with luting composite resin chairside milling. More recent studies have evaluated newer CAD/
instead of resin cement. A total of 15 restorations (8%) failed in CAM materials. A randomized clinical study compared leucite-
10 years, primarily due to either restoration or tooth fracture.35 reinforced (Paradigm C, 3M ESPE) and feldspathic (Vita Mark
In a follow-up report of that study, the authors reported less than II, Vita) CEREC onlays cemented with a self-etching, self-adhesive
3% drop in survival rate for the same restorations at 17 years, resin cement (RelyX Unicem, 3M ESPE). No statistically signiicant
with reported Kaplan-Meier survival probability of 88.7%. Six diferences in the clinical performance were noted between the
restorations failed during the 7-year period between evaluations, two materials at 3 years.40 his trend continued to be observed at
once again primarily due to either restoration or tooth fracture.36 the 5-year follow-up as no statistically signiicant diference was
Compared to clinical studies using early versions of the CEREC noted in margin adaptation between the two materials either at 5
system, these more recent studies reported better survival years or when results were compared to baseline values. However,
probabilities. an increased trend for localized crevice formation was noted over
he clinical survival of CAD/CAM restorations is inluenced time and a statistically signiicant diference was found between
by the adhesive cementation, which in turn is maximized with the baseline and 5-year data for both materials when more discriminative
presence of enamel margins. his was well demonstrated by a criteria were applied.41
longitudinal study on clinical performance of nonretentive feld- Chairside CAD/CAM systems were initially limited to the
spathic CAD/CAM overlays (occlusal veneers). A single operator fabrication of inlays and onlays since crowns were not possible
placed 310 CEREC overlays paying particular attention to keeping with the milling instruments irst introduced; therefore most of
preparation margins within enamel whenever possible. After 8 the initial studies focus on chairside all-ceramic inlays and onlays.
years of follow-up, 286 paired onlays were available for evaluation With the advent of newer materials and evolution of the milling
and the calculated survival rate was 99.3%. he only two fractures systems, an increased number of publications focus on chairside
observed in this study were on maxillary premolars of one patient CAD/CAM crowns. Reich and coworkers reported a short-term
with occlusal parafunction.37 he clinical success of these restorations clinical study on the performance of chairside CAD/CAM IPS
was likely due to the predictable bonding that is often achieved e.maxCAD crowns fabricated with the CEREC system. Forty-one
whenever the all-ceramic preparation is within enamel. In addition, full-contour e.maxCAD crowns were placed in 34 patients and
an experienced operator may have inluenced such remarkable 39 were available for the 24-month recall. Kaplan-Meier analysis
performance, as more inexperienced operators did not achieve revealed a 2-year survival rate of 97.4%. However, the failures
similar results. For example, a short-term prospective randomized observed were not due to crown fracture; one crown exhibited
controlled clinical trial looked at the clinical performance of 68 secondary caries and two crowns received root canal treatment.42
paired feldspathic CEREC onlays (Vitablock Mark II) that were In contrast, a large longitudinal clinical study evaluated the clinical
cemented with a self-adhesive cement (RelyX Unicem, 3M ESPE). performance of 100 IPS e.maxCAD CEREC crowns at 2, 4, and
he inluence of selective enamel etching was evaluated so each 5 years.43-45 All crowns were fabricated and delivered at a single
patient had one onlay cemented with the self-etch technique and appointment. he irst 62 crowns were placed with either a self-
the other one after selective etching. Statistically signiicant changes etching bonding agent and resin cement or a self-adhesive resin
were observed for marginal adaptation and marginal discoloration cement. he last group consisted of 38 crowns that were delivered
between baseline and 2 years but no statistically signiicant diference using an experimental self-etching, self-curing cement. No crown
in clinical performance was recorded between the two diferent failures were reported during the irst 24 months, therefore the
cementation groups. Two onlays debonded, one from each group; 2-year survival rate was 100%. A total of ive failures were recorded
two onlays fractured from the self-etch group. he 2-year failure at 5 years, four crowns debonded (three of which had been delivered
rate for CEREC feldspathic onlays was 5.1% for the self-etch with the experimental cement that never made it to market), and
technique and 1.7% for the selective etching group. he authors one crown fractured, for a 95% survival rate at 5 years. his study
concluded that selective enamel etching did not statistically sig- is currently ongoing and the optimistic trends continue to be
niicantly inluence the results.38 However, the failure to ind observed.
signiicance could be attributed to the short follow-up time. here is considerable published clinical research on chairside
Long-term clinical trials indicate that failures tend to continue to CAD/CAM technology that has revealed it to be a valuable tool
increase over time. for the delivery of high-quality restorations delivered during a
A long-term randomized clinical trial was designed to access single appointment. he ability to adhesively bond ceramic restora-
the longitudinal performance of 80 inlays machined from either tions at the time of restoration fabrication minimizes the occurrence
a composite resin material (Paradigm MZ100) or feldspathic of postoperative sensitivity while allowing for more conservative
ceramic (Vitablocks Mark II), cemented with a dual-cured resin tooth preparation as no preparation retention is required to retain
cement (RelyX ARC) using a total-etch bonding technique. At a temporary restoration. Research studies have assessed an extensive
the 10-year recall 89% of the inlays were available for evaluation. variety of resin-based, porcelain, glass ceramic, and high-strength
No statistically signiicant diference in margin adaptation was ceramic materials that may be used to provide restorative solutions
evident between the two materials; however, a signiicant decrease for inlays, onlays, veneers, and full crowns.
 CHAPTER 12 Digital Dentitry in Operative Dentitry 451

Concluion 19. Della Bona A, Corazza PH, Zhang Y: Characterization of a polymer-

iniltrated ceramic-network material. Dent Mater 30(5):564–569,
he clinical application of CAD/CAM technology has developed 2014.
through a continuous evolution of the hardware and software. 20. El Zhawi H, Kaizer MR, Chughtai A, et al: Polymer iniltrated
ceramic network structures for resistance to fatigue fracture and wear.
A variety of restorative materials are available to ofer alternative
Dent Mater 2016, pii: S0109-5641(16)30362-1. doi:10.1016/j.
solutions for a variety of clinical problems. Laboratory and clinical dental.2016.08.216. [Epub ahead of print].
research has documented the accuracy, longevity, and efectiveness 21. Rusin RP: Properties and applications of a new composite block for
of CAD/CAM fabricated restorations. he eicient treatment CAD/CAM. Compend Contin Educ Dent 22(6 Suppl):35–41, 2001.
worklow provides an opportunity for patient-centered treatment 22. Guazzato M, Albakry M, Ringer SP, et al: Strength, fracture toughness
in one appointment. he evidence-based reliability, as well as and microstructure of a selection of all-ceramic materials. Part II.
the perceived value of same-day dentistry, has helped secure a Zirconia-based dental ceramic. Dent Mater 20:449–456, 2004b.
permanent spot for CAD/CAM dentistry in operative dentistry 23. Boitelle P, Mawussi B, Tapie L, et al: A systematic review of CAD/
practice. CAM it restoration evaluations. J Oral Rehabil 41:853–874, 2014.
24. Seelbach P, Brueckel C, Wostmann B: Accuracy of digital and
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