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
indicated that few general dental
practitoners are happy to carry out surgical
crown lengthening.1 It is hoped that
this article will enable them to identify
situations where such a procedure would
benefit the patient and allow a referral as
The need for crown lengthening
is dictated by dental and patient factors.
After crown lengthening it should be
possible to put restoration margins
above, or at, the gingival margin. It is well
documented in the literature that this
creates a more favourable condition to
allow periodontal health. Silness2 found
that margins of fixed prosthodontics
significantly compromise the gingival
health, if placed below the gingival margin.
In a study3 it was found that subgingival
margins demonstrated higher plaque,
gingival index scores and probing depths. In
addition, when the bacterial morphotypes
were examined, there was an increase in the
spirochetes, fusiforms, rods and filamentous
bacteria. There is an additional benefit of
ease of impression taking, cleansing4 and
detection of secondary caries.
Periodontal health is the
cornerstone of any successful restorative
procedure. Therefore the correct handling
of the periodontal tissues during restoration
of the tooth is important to the restoration’s
In order to aid the restorative
dentist in understanding crown
lengthening procedure for restorative and
aesthetic reasons, the indications, contra-
indications, biological concepts and surgical
techniques will be discussed.
The indications for crown
? To increase clinical crown height lost due
Joanne Cunliffe, BChD, MRD, FDS RCS,
DPDS, SpR, Restorative Dentistry and
Nick Grey, BDS, PhD, MDSC, DRD, MRD,
FDS RCSEd, MILT, Senior Clinical Teacher/
Honorary Consultant Restorative
Dentistry, Manchester Dental Hospital,
Higher Cambridge Street, Manchester, UK.
to caries, fracture or wear;
? To access subgingival caries;
? To produce a ‘ferrule’ for post crown
? To access a perforation in the coronal
third of the root;
? To relocate margins of restorations that
are impinging on biological width.
? Short teeth;
? Uneven gingival contour;
? ‘Gummy smile’.
Figure 1. Thick tissue biotype with crown margin
impinging on the biological width. This has led to
30 DentalUpdate January/February 2008
When planning a restoration
where the margin will be within 3 mm
of the crestal bone, crown lengthening
should be considered; as the restoration
may impinge on the ‘biological width’,
which is the distance from the crest of the
bone to the margin of the gingivae. If it is
encroached upon, then this may lead to
gingival recession in thin tissue biotypes or
hyperplasia in thick tissue biotypes (Figure
Where there has been
toothwear, compensatory alveolar eruption
may or may not have occurred. In situations
where it does not occur, a better aesthetic
result may be produced by providing an
overdenture because the incisal edge
is in a more apical position (Figure 2).
In cases where compensatory alveolar
eruption has occurred, the lip position and
the incisal edge relationship may have
remained constant. This being the case,
it may be preferable to crown lengthen
in order to avoid a ‘gummy’ smile, gain
adequate tooth structure, provide both a
retentive restoration, as well as improve the
When there has been loss of
tooth structure due to caries or tooth
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).
Symmetrical smiles are deemed
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
If there is sufficient supracrestal
tissue, this outcome may be achieved with
a gingivectomy alone; otherwise, bone
removal is required. Whichever method
is used, it is very important that the
interdental papillae are maintained through
careful planning and consideration of
biological and anatomical factors.
Crown lengthening of a single
tooth or teeth with long clinical crowns may
yield unfavourable aesthetic results, such
as a ‘black triangle’ (Figure 6). As with any
treatment, crown lengthening is contra-
indicated in patients with poor oral hygiene.
There should also be caution
when treating a smoker because of reports
of poorer results in both non-surgical
therapy7 and surgical therapy8 for treatment
of periodontitis in smokers.
When crown lengthening is
planned to increase the length of available
tooth, the biological width needs to be
considered and not encroached upon as
this may lead to periodontal breakdown.9
Gargiulo et al10 described the
‘biological width’ in a histological study.
Large variations in this measurement
Figure 2. (a) Wear on the upper anterior teeth with
no alveolar compensation.
Figure 2. (b) Patient shows no upper teeth and
would benefit from an overdenture.
Figure 3. (a) Failed post crowns with very little
Figure 3. (b) Surgical crown lengthening with
electrosurgery to allow a ferrule to be used.
Figure 4. (a) Amelogenesis imperfecta patient
with posterior toothwear. There is adequate tooth
height to place an indirect restoration on the
lower left first molar.
Figure 4. (b) Patient has had surgical crown
lengthening to increase the vertical height of the
lower left first molar.
32 DentalUpdate January/February 2008
found, but the average was 0.69 mm mean
sulcus depth, 0.97 mm epithelial attachment
and 1.07 mm for connective tissue
attachment. This then totals 2.73 mm mean
length of the dentogingival complex.
Owing to the concept of
‘biological width’, it has been proposed that
there should be 3 mm of supracrestal tooth
tissue between the bone and the margin of
the proposed restoration.9 But there have
been other recommendations of between 3.5
mm and 5.25 mm11,12
While these measurements are
provided as a guide, one needs to remember
that there are variations between individuals
and around different teeth. It was observed
that there was a re-establishment of the
biological width in teeth that were crown
lengthened by 6 months. The re-established
biological width was found to be the same
vertical dimension as the pre-surgery
Anatomical considerations need
to be taken into account when a patient
is being assessed for crown lengthening,
? Length and shape of root;
? Furcation position;
? Lip line (at rest and smiling);
? Width of interdental bone;
? Local soft/hard tissue anatomy and muscle
? Amount of attached gingival tissue.
There needs to be a favourable
crown:root ratio after treatment, as well
as adequate tooth tissue to allow the
accommodation of the restoration. If the
tooth narrows considerably apically, there
may be a risk of pulp exposure during
preparation or risk of overcontouring the
restoration owing to insufficient space. In
addition, there is a risk of compromising the
appearance if the crown has to be over
If the furcation is exposed
during the bone removal, an area of plaque
stagnation, which may lead to more bone
loss, may occur. It has been demonstrated
that there needs to be 4 mm from the
furcation to the crestal bone pre-operatively
in order to reduce the risk of furcation
If the roots are close together,
there may be very little interdental bone,
which may make it impossible to use an
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
The position of the lip on
smiling will have an effect on the aesthetic
outcome. Therefore, the examination of
the lip position is important, as it will
determine the amount of tooth and
gingiva on display.15
If only one tooth needs
treatment and there is a higher lip line,
then the gingival discrepancy will be seen
and the resultant aesthetics poor. Other
soft tissue considerations are the muscle
insertions, as a high muscle insertion
may affect the apical repositioning of the
flap. This is also true if there is a shallow
vestibular sulcus or a high external oblique
ridge, as it may limit the position of the
The amount of attached
gingiva needs to be measured as part of
the assessment. It has been shown that, to
maintain periodontal health, there should
be 2–3 mm of attached gingival.16
Soft tissue recontouring
This technique is generally
used to improve aesthetics and takes the
form of a gingivectomy to excise the soft
tissue. Normally, the gingival margin is
1 mm coronal to the CEJ. If it is greater,
then the clinical crown is shorter than the
Figure 5. (a) Uneven gingival contour around the
upper anterior teeth with a temporary bridge. This
patient had a high lip line which made the contour
of the gingival important.
Figure 5. (b) Electrosurgery was used to recontour
and increase the length of the upper left central
and right lateral.
Figure 6. ‘Black triangles’.
Figure 7. (a) Pigmented gingiva needing crown
Figure 7. (b) Internal bevel gingivectomy
undertaken to keep the pigmented gingiva.
34 DentalUpdate January/February 2008
anatomical crown. In thin tissue biotypes,
a gingivectomy will expose more of the
crown and improve the appearance. It may
be achieved with a scalpel, or with the use
If there is pigmentation in the
tissue, it needs to be determined if the
patient wishes to maintain or lessen this
amount. An external bevel incision will
remove pigment, and it may be necessary
to extend the gingivectomy to the premolar
region to stop a marked transition being
visible on smiling. This colour change
may be permanent, but occasionally the
pigment returns slowly. If the patient wishes
to keep the pigment, then an internal bevel
incision is needed to produce an internal
gingivectomy (Figure 7).
Soft tissue and bone recontouring
When there is a thick tissue
biotype, especially with a ledge on the
crestal bone, an apically repositioned flap
and bone recontouring may be preferable.
If there is adequate attached
gingiva, labially or buccally, then an inverse
bevel incision can be made 2–3 mm from
the gingival margin, following a scalloped
pattern around the gingival margins. This
would be followed by a second incision
into the intracrevicular sulcus (Figure 8a).
The incision should be extended distally
1–2 teeth to blend into the gingival sulcus
of the untreated teeth. A third incision
is then placed interproximally to release
the interdental papillae, after which a
full thickness flap is raised to allow bone
exposure, the osseous recontouring. If there
is inadequate attached gingiva, then a
vertical releasing incision should be made
and the flap apically repositioned. Vertical
releasing incisions are also used if there is a
need for increased visibility or to avoid the
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
flap is then recontoured to follow the new
position of the bone.
Bone recontouring can be
carried out using fissure burs or coarse
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).
Enough bone is removed to create a 3 mm
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
to show the restoration’s expected margin
If the last tooth to be crown
lengthened is the most distal tooth, then
the incision needs to blend into a wedge
flap to reduce the bulk of the tissue distal to
the last tooth.
Sutures and dressing
Continuous or interrupted
sutures can be used. The continuous sutures
are particularly useful if there have been
several teeth with apically repositioned flaps.
The use of a periodontal dressing
is one of personal preference. The authors
do not use them and prefer to achieve full
bone coverage with the soft tissue flaps.
As with any procedure, the
patient needs to be informed of any
potential complications. For crown
lengthening these include:
? Possible poor aesthetics due to ‘black
? Root sensitivity;
? Root resorption;
? Transient mobility of the teeth.
Figure 8. (a) Shows the first incision and the
second incision being undertaken.
Figure 8. (b) Full thickness flap raised to expose
the bone. Note there are no relieving incisions
required in this case.
Figure 8. (c) Osseous recontouring using a rose-
head bur with copious saline.
Figure 8. (d) Flap repositioned before suturing.
Figure 9. A surgical stent made of acrylic to
use during surgery to indicate the proposed
restoration margins. The bone can be removed
3mm apical to this margin.
Restoration of the teeth
The gingival margin does
not stabilize until at least 20 weeks post
surgery.17 This is of particular importance
when in the anterior region as the
aesthetics may be more crucial. After a
2–3 week post surgery period, temporary
crowns may be used until there has been
full healing and the gingival margin is in a
Crown lengthening should
be within the capabilities of a specialist
restorative dentist. The most likely
specialist to perform this procedure has
been shown to be a periodontist.1
There is no reason
why general practitioners who are
comfortable with surgical dentistry
should not perform crown lengthening.
However, if this procedure lies outside
their ‘comfort zone’ then a referral to a
specialist is appropriate.
Surgical crown lengthening
has an important role in restorative
dentistry and, in dentitions that are worn,
it is a necessary consideration when
treatment planning is being undertaken.
Thanks to Stephen Brindley
for the help on some of the clinical
1.Wyatt G, Grey N, Deery C. A cross
sectional survey of clinicians
performing periodontal surgical crown
lengthening. Eur J Prosthodont Restor
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2. Silness J. Fixed prosthodontics and
periodontal health. Dent Clin N Am
1980; 24: 317–339.
3.Flores-de-Jacoby L, Zafiropoulas GG,
Cianco S. The effect of crown margin
location on plaque and periodontal
health. Int J Perio Rest Dent 1989; 9:
4.Silness J. Periodontal conditions in
patients treated with dental bridges
II. The influence of full and partial
crowns on plaque accumulation and
development of gingivitis and pocket
formation. Int J Perio Rest Dent 1970; 5:
5.Hemmings KW, King PA, Setchell DJ.
Resistance to torsional forces of various
post and core designs. J Prosthet Dent
1991; 66: 325–329.
6. Kay HB. Esthetic considerations in
the definitive periodontal prosthetic
management of the maxillary anterior
segment. Int J Perio Rest Dent 1982; 2:
7.Preber H, Bergstrom J. The effects of
non-surgical therapy on periodontal
pockets in smokers and non smokers.
J Clin Periodontol 1986; 13: 319–323.
8. Preber H, Bergstrom J. Effect of
cigarette smoking on periodontal
healing following surgical therapy. J Clin
Periodontol 1990; 17: 324–328.
9.Nevins M, Skurow HM. The
intracrevicular restorative margin, the
biological width and maintenance of
the gingival margin. Int J Perio Rest Dent
1984; 4: 30–49.
10. Gargiulo A, Wentz F, Orban B.
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gingival junction in humans.
J Periodontal 1961; 32: 261–267.
11. Rosenberg ES, Garber DA, Evian C.
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Exposing adequate tooth structure
for restorative dentistry. Int J Perio Rest
Dent 1989; 9: 322–333.
13. Lanning SK, Waldrop TC, Gunsolley J,
Maynard JG. Surgical crown
lengthening: evaluation of the
biological width. J Periodontol 2003;
14. Dibart S, Capri D, Kachouh I et al.
Crown lengthening in mandibular
molars; a 5 year retrospective
radiological analysis. J Periodontol
2003; 74: 815–882.
15. Tjan AHL, Miller GD, The JGP. Some
aesthetic factors in a smile. J Prosthet
Dent 1984; 51: 24–28.
16. Maynard JG Jr, Wilson RDK.
Physiological dimensions of the
periodontium significant to the
restorative dentist. J Periodontol 1979;
17. Wise MD. Stability of the gingival
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HOW WELL DO YOUR COMPLETE
DENTURE PATIENTS CHEW?
RCT comparing posterior occlusal
forms for complete dentures. Sutton AF,
Worthington HV, McCord JF. Journal of
Dental Research 2007; 86: 651–655.
Technicians make complete dentures
with different occlusal forms, often at
their own discretion rather than the
clinician’s prescription. The flatter the
occlusal plane the easier to construct the
denture, but there is some evidence that
cusped posterior teeth actually function
better and give improved patient
satisfaction. This research aimed to
compare patient satisfaction with three
different types of posterior occlusal form,
zero-degree, anatomic and lingualized
Forty-five patients were
randomly assigned three sets of dentures
to wear over an eight-week period. The
dentures were identical other than the
occlusal tables. Statistical analysis of the
results revealed no difference in patient
satisfaction between the lingualized and
anatomical occlusal forms, but that both
of these were significantly preferable
to the zero-degree form. Interestingly
patients preferred the lingualized and
anatomical occlusal forms in four of the
five aspects of the survey, appearance,
cleaning, stability and chewing.
The results for speech showed no
difference between the three forms.
Clinicians should be aware
of these findings when writing the
technical prescription for complete
denture fabrication in the laboratory.
Glasgow Dental School