RestorativeDentistry

Joanne Cunliffe

Nick Grey

Crown Lengthening Surgery –

Indications and Techniques
Abstract: Crown lengthening is a surgical procedure aimed at removal of periodontal tissue to increase the clinical crown height. As
a restorative dentist using this technique of crown lengthening, one needs to have an understanding of biological width, indications,
technique, as well as some possible limitations. The authors aim to discuss these concepts in order that the restorative dentist can use
crown lengthening as part of an overall treatment plan in a controlled and predictable manner, taking into account biological factors.
Clinical Relevance: Today’s restorative dentist faces an apparent increase in patients exhibiting toothwear that may result in shortened
teeth, making crowning these teeth problematic. In addition, it is evident that patients are becoming more aware of the importance of a
pleasing smile. This article discusses crown lengthening as one way in which the restorative dentist can address both clinical demands.
Dent Update 2008; 35: 29-35

Results of a recent review study have significantly compromise the gingival

indicated that few general dental health, if placed below the gingival margin.
practitoners are happy to carry out surgical In a study3 it was found that subgingival
crown lengthening.1 It is hoped that margins demonstrated higher plaque,
this article will enable them to identify gingival index scores and probing depths. In
situations where such a procedure would addition, when the bacterial morphotypes
benefit the patient and allow a referral as were examined, there was an increase in the
appropriate. spirochetes, fusiforms, rods and filamentous
bacteria. There is an additional benefit of
ease of impression taking, cleansing4 and
Introduction detection of secondary caries.
The need for crown lengthening Periodontal health is the
is dictated by dental and patient factors. cornerstone of any successful restorative
After crown lengthening it should be procedure. Therefore the correct handling Figure 1. Thick tissue biotype with crown margin
possible to put restoration margins of the periodontal tissues during restoration impinging on the biological width. This has led to
above, or at, the gingival margin. It is well of the tooth is important to the restoration’s hyperplasia.
documented in the literature that this future success.
creates a more favourable condition to In order to aid the restorative
allow periodontal health. Silness2 found dentist in understanding crown
that margins of fixed prosthodontics lengthening procedure for restorative and to caries, fracture or wear;
aesthetic reasons, the indications, contra- „ To access subgingival caries;
indications, biological concepts and surgical „ To produce a ‘ferrule’ for post crown
techniques will be discussed. provision;
„ To access a perforation in the coronal
Joanne Cunliffe, BChD, MRD, FDS RCS, third of the root;
DPDS, SpR, Restorative Dentistry and Indications „ To relocate margins of restorations that
Nick Grey, BDS, PhD, MDSC, DRD, MRD, The indications for crown are impinging on biological width.
FDS RCSEd, MILT, Senior Clinical Teacher/ lengthening are: Aesthetics
Honorary Consultant Restorative „ Short teeth;
Restorative needs
Dentistry, Manchester Dental Hospital, „ Uneven gingival contour;
„ To increase clinical crown height lost due
Higher Cambridge Street, Manchester, UK. „ ‘Gummy smile’.
January/February 2008 DentalUpdate 29
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 RestorativeDentistry

a b fracture, it has been shown that, when

providing a post crown, teeth prepared
with a ferrule of 1–2 mm have an increased
resistance to fracturing (Figure 3).5
There may also be a loss of tooth
tissue due to attrition and/or erosion. This
may leave inadequate tooth tissue to gain
enough vertical height to gain adequate
retention of an indirect restoration (Figure 4).
Figure 2. (a) Wear on the upper anterior teeth with Figure 2. (b) Patient shows no upper teeth and
no alveolar compensation. would benefit from an overdenture. Aesthetics
Symmetrical smiles are deemed
a b aesthetically pleasing and, ideally, there
should be 1 mm of gingivae visible when
smiling. The proportions of the crown
lengths are also important. The length of
the centrals should be equal to the canines
and the laterals slightly shorter than both
(Figure 5). The highest point of the scallop
should be slightly distal for the centrals, mid
point for the laterals and slightly distal for
the canines.6
If there is sufficient supracrestal
Figure 3. (a) Failed post crowns with very little Figure 3. (b) Surgical crown lengthening with tissue, this outcome may be achieved with
coronal tissue. electrosurgery to allow a ferrule to be used. a gingivectomy alone; otherwise, bone
removal is required. Whichever method
a b is used, it is very important that the
interdental papillae are maintained through
careful planning and consideration of
biological and anatomical factors.

Contra-indications
Crown lengthening of a single
Figure 4. (a) Amelogenesis imperfecta patient
tooth or teeth with long clinical crowns may
with posterior toothwear. There is adequate tooth Figure 4. (b) Patient has had surgical crown yield unfavourable aesthetic results, such
height to place an indirect restoration on the lengthening to increase the vertical height of the as a ‘black triangle’ (Figure 6). As with any
lower left first molar. lower left first molar. treatment, crown lengthening is contra-
indicated in patients with poor oral hygiene.
There should also be caution
when treating a smoker because of reports
Restorative where it does not occur, a better aesthetic of poorer results in both non-surgical
When planning a restoration result may be produced by providing an therapy7 and surgical therapy8 for treatment
where the margin will be within 3 mm overdenture because the incisal edge of periodontitis in smokers.
of the crestal bone, crown lengthening is in a more apical position (Figure 2).
should be considered; as the restoration In cases where compensatory alveolar
may impinge on the ‘biological width’, eruption has occurred, the lip position and
Biological considerations
which is the distance from the crest of the the incisal edge relationship may have Biological width
bone to the margin of the gingivae. If it is remained constant. This being the case, When crown lengthening is
encroached upon, then this may lead to it may be preferable to crown lengthen planned to increase the length of available
gingival recession in thin tissue biotypes or in order to avoid a ‘gummy’ smile, gain tooth, the biological width needs to be
hyperplasia in thick tissue biotypes (Figure adequate tooth structure, provide both a considered and not encroached upon as
1). retentive restoration, as well as improve the this may lead to periodontal breakdown.9
Where there has been aesthetics. Gargiulo et al 10 described the
toothwear, compensatory alveolar eruption When there has been loss of ‘biological width’ in a histological study.
may or may not have occurred. In situations tooth structure due to caries or tooth Large variations in this measurement

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 RestorativeDentistry

a b

Figure 6. ‘Black triangles’.

furcation to the crestal bone pre-operatively

Figure 5. (a) Uneven gingival contour around the in order to reduce the risk of furcation
upper anterior teeth with a temporary bridge. This Figure 5. (b) Electrosurgery was used to recontour exposure.14
patient had a high lip line which made the contour and increase the length of the upper left central If the roots are close together,
of the gingival important. and right lateral. there may be very little interdental bone,
which may make it impossible to use an
a b instrument in between the teeth for bone
removal without risking damaging the
roots. If the bone is not removed from the
interproximal area, then it may be difficult
to reposition the soft tissues, and there will
be a reduction in the length that is gained,
thereby compromising the retention of a
restoration.
The position of the lip on
smiling will have an effect on the aesthetic
Figure 7. (a) Pigmented gingiva needing crown Figure 7. (b) Internal bevel gingivectomy outcome. Therefore, the examination of
lengthening. undertaken to keep the pigmented gingiva.
the lip position is important, as it will
determine the amount of tooth and
gingiva on display.15
found, but the average was 0.69 mm mean to be taken into account when a patient If only one tooth needs
sulcus depth, 0.97 mm epithelial attachment is being assessed for crown lengthening, treatment and there is a higher lip line,
and 1.07 mm for connective tissue including: then the gingival discrepancy will be seen
attachment. This then totals 2.73 mm mean „ Length and shape of root; and the resultant aesthetics poor. Other
length of the dentogingival complex. „ Furcation position; soft tissue considerations are the muscle
Owing to the concept of „ Lip line (at rest and smiling); insertions, as a high muscle insertion
‘biological width’, it has been proposed that „ Width of interdental bone; may affect the apical repositioning of the
there should be 3 mm of supracrestal tooth „ Local soft/hard tissue anatomy and muscle flap. This is also true if there is a shallow
tissue between the bone and the margin of insertions; vestibular sulcus or a high external oblique
the proposed restoration.9 But there have „ Amount of attached gingival tissue. ridge, as it may limit the position of the
been other recommendations of between 3.5 There needs to be a favourable flap.
mm and 5.25 mm11,12 crown:root ratio after treatment, as well The amount of attached
While these measurements are as adequate tooth tissue to allow the gingiva needs to be measured as part of
provided as a guide, one needs to remember accommodation of the restoration. If the the assessment. It has been shown that, to
that there are variations between individuals tooth narrows considerably apically, there maintain periodontal health, there should
and around different teeth. It was observed may be a risk of pulp exposure during be 2–3 mm of attached gingival.16
that there was a re-establishment of the preparation or risk of overcontouring the
biological width in teeth that were crown restoration owing to insufficient space. In
lengthened by 6 months. The re-established addition, there is a risk of compromising the
Techniques
biological width was found to be the same appearance if the crown has to be over Soft tissue recontouring
vertical dimension as the pre-surgery contoured. This technique is generally
measurement.13 If the furcation is exposed used to improve aesthetics and takes the
during the bone removal, an area of plaque form of a gingivectomy to excise the soft
stagnation, which may lead to more bone tissue. Normally, the gingival margin is
Anatomical considerations loss, may occur. It has been demonstrated 1 mm coronal to the CEJ. If it is greater,
Anatomical considerations need that there needs to be 4 mm from the then the clinical crown is shorter than the

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 RestorativeDentistry

a b exposure of a crown margin.

Palatally, a scalloped inverse
bevel incision using a number 15 blade
should be made, again following a scalloped
pattern, but this time the scallop is much
deeper than the original gingival margins.
Alternatively, intra-crevicular incisions can
be used and a full thickness flap raised
(Figure 8b); after the bone recontouring, the
Figure 8. (b) Full thickness flap raised to expose flap is then recontoured to follow the new
Figure 8. (a) Shows the first incision and the the bone. Note there are no relieving incisions position of the bone.
second incision being undertaken. required in this case. Bone recontouring can be
carried out using fissure burs or coarse
c d
diamond stones with copious amounts
of normal saline (Figure 8c). The bone is
thinned until there is a thin layer remaining
over the surface. To reduce the risk of
damaging the root surface, the authors
consider that this final thin layer of bone
should be removed by using a bone chisel,
files or an ultrasonic scaler. Then any
bone ledges should be smoothed to aid
the repositioning of the flap (Figure 8d).
Figure 8. (c) Osseous recontouring using a rose- Enough bone is removed to create a 3 mm
head bur with copious saline. Figure 8. (d) Flap repositioned before suturing.
space between the crest of the bone and
the new restoration’s margin. This can be
measured using a periodontal probe, or a
surgical stent can be made in the laboratory
pigment returns slowly. If the patient wishes
to show the restoration’s expected margin
to keep the pigment, then an internal bevel
(Figure 9).
incision is needed to produce an internal
If the last tooth to be crown
gingivectomy (Figure 7).
lengthened is the most distal tooth, then
the incision needs to blend into a wedge
Soft tissue and bone recontouring flap to reduce the bulk of the tissue distal to
When there is a thick tissue the last tooth.
biotype, especially with a ledge on the
crestal bone, an apically repositioned flap
Figure 9. A surgical stent made of acrylic to Sutures and dressing
and bone recontouring may be preferable.
use during surgery to indicate the proposed Continuous or interrupted
If there is adequate attached
restoration margins. The bone can be removed sutures can be used. The continuous sutures
gingiva, labially or buccally, then an inverse
3mm apical to this margin. are particularly useful if there have been
bevel incision can be made 2–3 mm from
several teeth with apically repositioned flaps.
the gingival margin, following a scalloped
The use of a periodontal dressing
pattern around the gingival margins. This
is one of personal preference. The authors
anatomical crown. In thin tissue biotypes, would be followed by a second incision
do not use them and prefer to achieve full
a gingivectomy will expose more of the into the intracrevicular sulcus (Figure 8a).
bone coverage with the soft tissue flaps.
crown and improve the appearance. It may The incision should be extended distally
be achieved with a scalpel, or with the use 1–2 teeth to blend into the gingival sulcus
of electrosurgery. of the untreated teeth. A third incision Complications
If there is pigmentation in the is then placed interproximally to release As with any procedure, the
tissue, it needs to be determined if the the interdental papillae, after which a patient needs to be informed of any
patient wishes to maintain or lessen this full thickness flap is raised to allow bone potential complications. For crown
amount. An external bevel incision will exposure, the osseous recontouring. If there lengthening these include:
remove pigment, and it may be necessary is inadequate attached gingiva, then a „ Possible poor aesthetics due to ‘black
to extend the gingivectomy to the premolar vertical releasing incision should be made triangles’;
region to stop a marked transition being and the flap apically repositioned. Vertical „ Root sensitivity;
visible on smiling. This colour change releasing incisions are also used if there is a „ Root resorption;
may be permanent, but occasionally the need for increased visibility or to avoid the „ Transient mobility of the teeth.

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 RestorativeDentistry

Restoration of the teeth References 9. Nevins M, Skurow HM. The

The gingival margin does 1. Wyatt G, Grey N, Deery C. A cross intracrevicular restorative margin, the
not stabilize until at least 20 weeks post sectional survey of clinicians biological width and maintenance of
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when in the anterior region as the lengthening. Eur J Prosthodont Restor 1984; 4: 30–49.
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2–3 week post surgery period, temporary 2. Silness J. Fixed prosthodontics and Dimensions and relations of dento
crowns may be used until there has been periodontal health. Dent Clin N Am gingival junction in humans.
full healing and the gingival margin is in a 1980; 24: 317–339. J Periodontal 1961; 32: 261–267.
stable position. 3. Flores-de-Jacoby L, Zafiropoulas GG, 11. Rosenberg ES, Garber DA, Evian C.
Cianco S. The effect of crown margin Tooth lengthening procedures.
Compend Continuing Educ Dent 1980;
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Discussion health. Int J Perio Rest Dent 1989; 9:
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restorative dentist. The most likely patients treated with dental bridges
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specialist to perform this procedure has II. The influence of full and partial
13. Lanning SK, Waldrop TC, Gunsolley J,
been shown to be a periodontist.1 crowns on plaque accumulation and
Maynard JG. Surgical crown
There is no reason development of gingivitis and pocket
lengthening: evaluation of the
why general practitioners who are formation. Int J Perio Rest Dent 1970; 5:
biological width. J Periodontol 2003;
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should not perform crown lengthening. 5. Hemmings KW, King PA, Setchell DJ. 14. Dibart S, Capri D, Kachouh I et al.
However, if this procedure lies outside Resistance to torsional forces of various Crown lengthening in mandibular
their ‘comfort zone’ then a referral to a post and core designs. J Prosthet Dent molars; a 5 year retrospective
specialist is appropriate. 1991; 66: 325–329. radiological analysis. J Periodontol
6. Kay HB. Esthetic considerations in 2003; 74: 815–882.
the definitive periodontal prosthetic 15. Tjan AHL, Miller GD, The JGP. Some
Conclusion management of the maxillary anterior aesthetic factors in a smile. J Prosthet
Surgical crown lengthening segment. Int J Perio Rest Dent 1982; 2: Dent 1984; 51: 24–28.
has an important role in restorative 45. 16. Maynard JG Jr, Wilson RDK.
dentistry and, in dentitions that are worn, 7. Preber H, Bergstrom J. The effects of Physiological dimensions of the
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Thanks to Stephen Brindley cigarette smoking on periodontal crest after surgery and before anterior
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photos. Periodontol 1990; 17: 324–328. 53: 20–23.

Abstract
HOW WELL DO YOUR COMPLETE better and give improved patient of these were significantly preferable
DENTURE PATIENTS CHEW? satisfaction. This research aimed to to the zero-degree form. Interestingly
RCT comparing posterior occlusal compare patient satisfaction with three patients preferred the lingualized and
forms for complete dentures. Sutton AF, different types of posterior occlusal form, anatomical occlusal forms in four of the
Worthington HV, McCord JF. Journal of zero-degree, anatomic and lingualized five aspects of the survey, appearance,
Dental Research 2007; 86: 651–655. occlusions. cleaning, stability and chewing.
Forty-five patients were The results for speech showed no
Technicians make complete dentures randomly assigned three sets of dentures difference between the three forms.
with different occlusal forms, often at to wear over an eight-week period. The Clinicians should be aware
their own discretion rather than the dentures were identical other than the of these findings when writing the
clinician’s prescription. The flatter the occlusal tables. Statistical analysis of the technical prescription for complete
occlusal plane the easier to construct the results revealed no difference in patient denture fabrication in the laboratory.
denture, but there is some evidence that satisfaction between the lingualized and Peter Carrotte
cusped posterior teeth actually function anatomical occlusal forms, but that both Glasgow Dental School

January/February 2008 DentalUpdate 35

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