Crown lengthening and restorative procedures in the esthetic zone

1. In the name of God
By Seyedeh Marzieh Hashemi Nejad

3.  Crown lengthening is one of the most common surgical procedures in
periodontal practice. A recent American Academy of Periodontology
survey reported that approximately 10% of all periodontal surgical
procedures are performed in order to achieve gain in crown length (1).
 The main indications of crown-lengthening surgical procedure include
treatment of subgingival caries, crown or root fractures, altered passive
eruption, cervical root resorption and short clinical abutment. The
rationale of crown lengthening is to reestablish the biologic width (e.g.
the natural distance between the base of the gingival sulcus and the
height of the alveolar bone) in a more apical position to avoid a violation
that may result in bone resorption, gingival recession, inflammation or
hypertrophy.

4. The concept of biologic width stems from the classic
histologic study by Gargiulo et al. (13), who measured
the average dimension of the epithelial junction (0.97
mm) and connective tissue attachment (1.07 mm) in
humans. These values were summed to provide the
biologic width, yielding an average dimension of 2.04
mm. A recent systematic review (22) found similar
mean values of biologic width (2.15–2.30 mm),
although considerable intra- and interindividual
variances were reported (subject sample range: 0.20–
6.73 mm).

5.  The integrity of the biologic width is considered a necessary step, in
restorative and prosthetic rehabilitations, to obtain and maintain
healthy soft tissues. While crown-lengthening procedures in
posterior areas have been investigated in detail, crown lengthening
performed for esthetic reasons in anterior areas is still a matter of
debate.
 A literature search on PubMed for ‘esthetic crown lengthening’
returned a list of 250 articles. Among these articles, there are no
systematic reviews and only a few controlled clinical trials (3, 5, 14,
16, 20).
 Moreover, anterior crown lengthening is often described as part of a
multidisciplinary orthodontic and restorative treatment plan. For
these reasons, although a number of surgical procedures are
described, an evidence-based technique is not available and many
questions still remain unanswered.

6. The purpose of this paper is to focus on the description
of the surgical and restorative phases in the esthetic
crown-lengthening procedure by answering the
following questions:
what is the ideal surgical flap design?
how much supporting bone should be removed?
how should the position of the flap margin relate to
the alveolar bone at surgical closure?
 and how should the healing phase be managed in
relation to the timing and the position of the
provisional restoration with respect to the gingival
margin?

7. Soft- and hard-tissue management
 Flap design (vestibular aspect)
 Flap design (palatal aspect)
 Ostectomy
 Osteoplasty
 Flap suturing and positioning

8. Flap design (vestibular aspect)
The flap is designed by creating submarginal parabolic
incisions, starting from the angular lines of the adjacent
teeth and crossing at the level of the interdental papillae,
thereby reproducing the natural scalloping of a patient’s
gingival margin. Correct placement of the primary incision
is based on the probing depth and on the amount of
keratinized tissue available (4, 7).
 In a patient with an ‘adequate’ dimension of keratinized
tissue, the distance of the primary incision from the gingival
margin is proportional to the differences in probing depth of
the adjacent teeth (6). If the amount of keratinized tissue is
‘inadequate’, the primary incision should be intrasulcular.

9.  it is recommended that there be at least
3.0 mm between the gingival margin and
bone crest
 In the case of caries or tooth fracture, to
ensure margin placement on sound tooth
structure and retention form, the surgery
should provide at least 4 mm from the
apical extent of the caries or fracture to
the bone crest

10.  Treatment Options For Crown Lengthening Procedures
1) Surgical
A) Gingivectomy
Conventional ( Scalpel or Kirkland knife)
Laser
Electrocautery
B) Internal Bevel Gingivectomy with or without ostectomy (also referred as flap surgery with
or without osseous surgery)
C) Apical positioning of flap with or without ostectomy
2) Combined (SURGICAL & NON SURGICAL) - Orthodontic Treatment
Crown Lengthening Procedures- A Review
Article

11. Clinical Procedures in Margin Placement
 The first step in using sulcus depth as a guide in margin placement is to manage
gingival health. Once the tissue is healthy, the following three rules can be used to
place intracrevicular margins:
 Rule 1: If the sulcus probes 1.5 mm or less, place the restorationmargin 0.5 mm below
the gingival tissue crest. This is especially important on the facial aspect and will
prevent a biologic width violation in a patient who is at high risk in that regard.
 Rule 2: If the sulcus probes more than 1.5 mm, place the margin half the depth of the
sulcus below the tissue crest. This places the margin far enough below tissue, so that it
will still be covered if the patient is at higher risk of recession.
 Rule 3: If a sulcus greater than 2 mm is found, especially on the facial aspect of the
tooth, evaluate to see if a gingivectomy could be performed to lengthen the teeth
and create a 1.5-mm sulcus. Then the patient can be treated using Rule 1.

12. A- Crown Lengthening Surgery Using
External Bevel Gingivectomy
 This technique is generally performed when there is sufficient sulcular depth and
keratinized tissue so that the incision does not violate the biologic width or cause
exposure of the bone. It can be performed with the help of scalpel or a Kirkland
knife (conventional), lasers or electrocautery.
 Reduction of soft tissue alone is indicated if there is adequate attached gingiva and
more than 3 mm of tissue coronal to the bone crest This may be accomplished by
either gingivectomy or flap technique.
Crown Lengthening Procedures- A Review Article

13. Crown Lengthening Surgery Using Internal Bevel
Gingivectomy With Or Without Ostectomy
(Undisplaced Flap)
 The initial or inverse bevel incision is made depending upon that how much crown
exposure is required. Then the second or the crevicular incision is made from the
bottom of the sulcus to the bone to detach the connective tissue from the bone.
The flap is then raised and third incision is given to remove the tissue tags. After
complete scaling and root planning flap is then sutured back in position.
Crown Lengthening Procedures- A Review Article

14.  General Tissue Assessment Before Under taking Cls
Soft Tissue Assessment
Situation1- If width of attached gingiva adequate-(>3mm)-external bevel gingivectomy or
internal bevel gingivectomy
Situation 2- If width of attached gingiva inadequate (<3mm)- apically positioned flap (If
soft-tissue excision via a gingivectomy would result in a postoperative gingival width of less
than 3 mm, one should consider the apically positioned flap as an alternative to a simple
gingivectomy.)
Hard Tissue Assessment
Situation1- If bone crest is low i.e. more apically – no ostectomy
Situation 2- If bone crest is high i.e. more coronal- ostectomy performe
Crown Lengthening Procedures- A Review Article

15.  Flap elevation is a controversial issue. The literature describes full-
thickness (3, 19), split-thickness (2) and split-full-split-thickness
approaches (4, 18, 25). The rationale of the split-thickness elevation is
to preserve the periostium in order to minimize postsurgical bone
resorption and to facilitate the apical suturing of the flap. The full-
thickness approach has the advantages of being easier to perform and
of gaining direct access to the bone than the split-fullsplit-thickness
and full-thickness approaches. The split-full-split-thickness approach
merges the positive aspects of both techniques: the papillae area is
elevated split-thickness in order to obtain a precise postsurgical
adaptation, while, apically, a full-thickness elevation is made in order to
gain access to the bone and to preserve the periosteum, which would
otherwise be lost during osteoplasty, at the inner aspect of the flap.
Once an adequate amount of bone has been exposed, a split-thickness
dissection can be performed to facilitate the apical anchorage of the
flap in the desired position (4, 7, 25).

16. full-thickness
 Periosteum is reflected to expose the underlying bone
 Indicated in resective osseous surgery
 Contraindications:
•Area where treatment for osseous defect with mucogingival problem is not required.
•Thin periodontal tissue with probable osseous dehiscence and osseous fenestration.
•Area where alveolar bone is thin

17. split-thickness
 •Periosteum covers the bone.
•Indicated when the flap has to be positioned apically.
•When the operator does not desire to expose the bone.

18. split-full-split-thickness
 The resulting trapezoidal-shaped flap was elevated with a split–full–split approach in the coronal–apical direction: the surgical
papillae comprised between the horizontal incisions and the probeable sulcular area apical to the root exposure were elevated
split thickness keeping the blade almost parallel to the root, and the soft tissue apical to the root exposure was elevated full
thickness inserting a small periostium elevator in to the probeable sulcus and proceeding in the apical direction up to exposing
3–4mm of bone apical to the bone dehiscence. This was done in order to include the periostium in the thickness of that central
portion of the flap covering the avascular root exposure. The releasing vertical incisions were elevated split thickness keeping the
blade parallel to the bone plane, thus leaving the periostium to protect the underlying bone in the lateral areas of the flap. Apical
to bone exposure flap elevation continued split thickness and finished when it was possible to move.

19. Flap design (palatal aspect)
 The palatal flap is raised using the thinned palatal flap approach (9). As the palatal flap cannot be moved
apically, the position of the primary incision must anticipate the future configuration of the crestal
bone and depends on the amount of crown lengthening required and on the palatal vault anatomy.
 In the presence of a shallow palatal vault the distance of the incision from the gingival margin is
exclusively related to the amount of crown lengthening required.
 In the presence of a deep palatal vault, the soft-tissue thickness has to be taken into consideration, with
thicker soft tissues necessitating a greater amount of tissue removal with the secondary palatal flap and
more pronounced apical repositioning of the flap.
 Hence, if the deep palatal vault has thick soft tissue, the primary incision should be less para-marginal
than if the deep palatal vault has thin tissues. Otherwise, there is a risk of incomplete coverage of the
palatal bone. In order to avoid excessive exposure of palatal bone, great care must be taken not to make
the incision too far from the gingival margin, especially in the case of a shallow vault or a deep palatal
vault with thick soft tissue.
 After vestibular and palatal flap reflection, the soft tissue delimited with the primary incisions is removed
using manual and ultrasonic devices.

20. Practical Periodontal Diagnosis and Treatment
Planning

23. Ostectomy
 Ostectomy consists of the removal of supporting bone (bone connected
to the root surface with periodontal ligament), and the amount of bone
resected is determined by the extent of the crown lengthening required.
Many authors have proposed a range of values (3 mm to > 5 mm) for
the amount of tooth structure to be exposed during crown-lengthening
procedures (12, 15–17, 21, 23). These ‘numbers’ are derived from the
histologic description of the dentogingival complex by Gargiulo et al.
(13). Although considerable variations were reported, the dimension of
the supra-osseous soft tissue was, on average, 2.73 mm.

24.  Other authors (16, 18) proposed a method to measure the
individual biologic width dimension using presurgical,
transmucosal probing. In particular, Lanning et al. (16)
reported a biologic width average of 2.26 ±0.13 mm, while
Perez et al. (18) measured a mean supra-osseous gingiva of
3.63 ± 0.64 (range: 2.67–5.00) mm. Although the mean values
of biologic width found in these studies are similar, the
significant range variability observed between patients makes
it reasonable to carry out presurgical biologic width or supra-
osseous gingiva measurements in order to personalize the
extent of bone removal.

25. Osteoplasty
 Osteoplasty consists of the removal of nonsupporting bone and aims
to thin the vestibular and lingual/ palatal aspects of alveolar bone
and to eliminate any osseous ledges or exostosis. It includes
techniques of vertical grooving and radicular blending aimed at
establishing physiologic osseous morphology and root prominence
(4, 6). The amount of bone required to be removed has not been
quantified in the literature, and whether osteoplasty is needed
requires a subjective clinical judgment. However, bone reduction
could be considered as complete when the flap can be precisely
adapted over the underlying bone.

26. Instrumentation
Bone is removed by high-speed drilling under copious irrigation
with sterile water. Aggressive, multitapered drills can be used
initially, followed by the use of diamond burs and handheld
chisels to refine the bone surface. Care must be taken to remove
all interproximal bone remnants (i.e. widow’s peaks) and to
prevent inadvertent trauma to the teeth. Root planing of the
exposed root surface is carried out using ultrasonic and hand
instruments to create a hard, smooth and clean root surface.

27. Flap suturing and positioning
The flap is sutured with vertical mattress sutures
anchored to the periosteum with the rationale of
obtaining a tight adaption of the flap to the
underlying tissues at the desired apical position.

28. Esthetic considerations
The goal of esthetic surgery is to mimic, as much as possible, the natural
aspect of soft tissues and to give a harmonious aspect to the surgical area.
The presurgical and surgical variables to be considered to achieve these
objectives are:
 The position of the vestibular incision. As the vestibular flap can be
precisely adapted to the bone crest and sutured at the desired position,
the vestibular incision should be mostly guided by considering the final
position of the mucogingival line after flap suturing, with the purpose of
obtaining a uniform band of keratinized tissue around the anterior teeth.
 Interdental soft tissues. The interdental soft tissues should be left in
place if no interproximal crown lengthening is required. This is the case if
a patient is affected by buccal passive altered eruption requiring
restorative rehabilitation.

29.  Ostectomy (Fig. 1). The tooth that will have the buccal bone crest
most apically displaced after ostectomy (for a restorative, ferrule
effect, or esthetic or periodontal reasons) has to be considered as
the ‘guiding tooth’. Once the guiding tooth is identified, the extent
of the ostectomy on the adjacent teeth should respect the following
esthetic proportion parameters: the apicocoronal position of the
bone crest should be at the same level of homologous contralateral
elements; the position of the bone crest of the central incisors
should be at the same level or more coronal to the bone crest of
the canines; and the position of the bone crest of the lateral incisors
should be more coronal to the bone crest of the central incisors and
canines.

30. Osteoplasty. The osteoplasty must be performed
accurately in order to establish physiologic and
harmonious vestibular bone morphology. How the
bone thickness is managed has a direct influence on
the appearance and rebound of soft tissues and the
tooth-emergence profiles.

32. Soft-tissue rebound
 The regrowth of soft tissue after the crown-lengthening procedure has been investigated
in detail.
 Bragger et al. (5), performed a study on 25 patients to assess changes in the soft-tissue
level after a crown-lengthening procedure with a 6-month follow-up. Immediately after
suturing, the surgical procedure resulted in apical displacement of the soft-tissue margin
by an average distance of 1.32 mm. At 6 months, stable periodontal tissues with minimal
changes in the gingival margin levels were reported. These data were partially confirmed
by Lanning et al. (16),
 in a study on 18 patients. These authors observed no significant change in the position of
the free gingival margin between 3- and 6-month time points (7.64 ± 0.32 and 7.90 ±
0.30 mm, respectively). As no postsurgical measures of the free gingival margin were
provided, a comparison between baseline (after flap suturing) and 3- to 6-month time
points is not possible.

33. .
 Conversely, Pontoriero & Carnevale (20), in a study on 30 patients, found
significant alterations of the marginal periodontal tissues from the
immediate postsurgical level (4.8 ± 1.7 mm interproximally and 5.7 ± 2.4
mm buccolingually) over a 12-month healing period (1.6 ± 1.4 mm
interproximally and 2.8 ± 2.6 mm buccolingually), indicating significant
coronal displacement of the newly formed soft-tissue margin.
 Moreover, a different pattern in the healing response between different
tissue biotypes was observed, with the coronal regrowth at interproximal
and buccal/lingual sites being significantly more pronounced in patients
with a thick tissue biotype than in patients with a thin tissue biotype.

34.  The tendency for a coronal shift of the soft-tissue margin during healing
was also confirmed by Perez et al. (18), Arora et al. (3), and Deas et al.
(10), on studies with 6 months of follow-up.
 In particular, Arora et al. (3) and Deas et al. (10) related the tissue
rebound to the postsurgical flap position, observing greater growth when
flaps were positioned closer to the alveolar crest.
 These findings underline the importance of a presurgical evaluation by
the clinician, and the extent of the ostectomy should be considered
according to the tissue biotype. Also, the clinician should be aware that
the position of the flap directly influences the soft-tissue rebound and
accordingly should choose an appropriate suture technique.

35. Wound healing
 Research has shown that when the clinician creates an apically positioned flap with
an osseous resection procedure, the biological width reestablishes itself at an
apical level.
 Researchers have observed that if the margin of the flap is positioned at the level
of the osseous crest, a postoperative vertical gain or rebound in supracrestal soft
tissues occurs that averages 3 mm.
 If the flap margin is placed at a level more coronal to the newly established
osseous crest, less vertical gain or rebound in supracrestal soft tissues has been
observed.
Contemporary crown-lengthening therapy

36.  A simple excision of tissue probably would result in regrowth of soft tissue if the
osseous crest is less than 3 mm apical to the existing free gingival margin.
 If reverse architecture remains after a tooth with a surrounding healthy
periodontium has undergone crown lengthening, excess gingival tissue may
rebound in the healing phase.
 Reduction of osseous ledging or an exostosis via osteoplasty was recommended
originally by Schluger32 in 1949 and subsequently by Friedman33 in 1955. It is our
opinion that reduction of alveolar bone enlargements reduces the risk of
postoperative rebound of soft tissue.
Contemporary crown-lengthening therapy

37. There was a significant inverse correlation between the distance from flap to bony
crest at the time of suturing and the amount of tissue rebound, indicating a greater
rebound when the flap margin was positioned closer to the bony crest. Flaps that
were sutured within 1 mm of the alveolar crest experienced the greatest coronal tissue
rebound.
 The amount of coronal tissue rebound decreased as the flaps were sutured more
coronally.
 Rebound was not observed when the flaps were sutured at a distance >4 mm
coronally.
ESTHETIC CROWN LENGTHENING:
GUIDELINES FOR ACHIEVING IDEAL GINGIVAL ARCHITECTURE AND STABILITY

38. Many factors seem to contribute to the maintenance of tooth structure gained
through surgical crown lengthening procedures. Individual patient healing
characteristics, reformation of the biologic width, adequacy of positive osseous
architecture created during surgery, timing of restorative procedures,different tissue
biotype, and post-operative plaque control may be among these factors. another
factor may be the position of the flap margin after surgery, which was examined in
the present study.
It is possible that earlier marginal tissue stability can be achieved if the gingival
margin is placed at the time of suturing in a position that accounts for the
reformation of the biologic width.

39. Provisional and definitive prosthetic
management
 Management of the provisional prosthetic restoration is a fundamental step in the
esthetic rehabilitation process that often troubles both the clinician and the patient. Three
procedures can be adopted based on the time point when the teeth are prepared and
on the position of the margins of the prosthesis with respect to the gingival margin:
 (i) intra-operative tooth preparation and relining of the provisional restoration;
 (ii) early tooth preparation and relining of the provisional restoration; and
 (iii) delayed tooth preparation and relining of the provisional restoration.

40. Intra-operative tooth preparation and
provisional relining
In this approach,
 tooth preparation is carried out during surgery, after ostectomy and osteoplasty, usually with the use of diamond
burs.
 Abutments are prepared with knife-edge margins at the bone crest level.
 The intra-operative preparation offers the following advantages:
1) elimination of undercuts;
2) root proximity correction;
3) and smoothing and cleansing of root surfaces by removing calculus and necrotic cement remnants.
After preparation of abutments the provisional restoration can be relined during surgery or immediately after
suturing.
Prosthetic margins should be positioned at a distance of at least 1 mm from the gingival level and constantly
monitored in order not to interfere with the healing of soft tissue.
The frequency with which the provisional restoration is modified is related to the expected soft-tissue rebound (i.e. the
position of the flap at time of suturing and the gingival biotype) (6).
The final prosthesis can be delivered when soft-tissue stability is observed.

41. Early tooth preparation and provisional relining
In this approach
tooth preparation occurs after 3 weeks from the surgery (25). During this period, the presurgical
provisional restoration is left in place.
The rationale for this approach is to manage the provisional prosthetic steps after the initial healing
has taken place and following restoration of the connective tissue attachment (i.e. the re-
establishment of the biologic width and during the maturation phase of the soft tissues).
In the first 3 weeks after surgery, approximately 1 mm of bone surrounding the teeth involved in the
surgery resorbs and leaves a portion of healthy root cementum available for connective tissue
attachment to re-form, in a more apical position (24).
The area previously occupied by the connective tissue attachment, where intra-operative root planing
was performed, is now a hard, smooth and clean surface onto which the junctional epithelium can
adhere (8).
Three weeks after surgery, the probing depth is zero and the sulcus and the interdental papillae are
still absent. From a clinical point of view, the tooth structure that, after the soft-tissue maturation, will
become subgingival is now still supragingival, thus facilitating management of the provisional
prosthetic restoration.

42.  The abutment preparation is now performed at, or close to, the gingival level with a knife-
edge margin and using the healed soft-tissue margin as a guide.
 A new provisional restoration is relined at the same level.
 The early tooth preparation offers the following advantages (25):
1) less aggressive abutment preparation;
2) the provisional prosthetic phase does not interfere with the re-establishment of the biologic
width;
3) no need for provisional relining at the end of surgery;
4) easy supragingival knife-edge preparation using the healed soft-tissue margin as a guide;
5) easy supragingival relining of the provisional restoration in a rested patient with no
bleeding;
6) conditioning of the soft tissues during the maximal regrowth period;
7) and no need for retraction cords during abutment preparation and relining of the
provisional restoration (necessary in the case of delayed tooth preparation and provisional
relining).

43.  The provisional restorations are modified further only in the interdental aspect, thus
avoiding unesthetic exposure of tooth structure during the entire healing phase. This also
minimizes hypersensitivity.
 The contact point is initially positioned at a distance of 3 mm from the interdental soft
tissues and is progressively shifted in a more coronal position, a millimeter at a time, as
the interdental space is filled by the soft-tissue regrowth.
 Also, the convergence of the provisional interproximal surfaces is gradually augmented,
to maximize the regrowth of the interdental papillae. The frequency of the provisional
modifications is related to the expected soft-tissue rebound.
 The time for the final impression is specifically chosen in each patient when, at the last
control visit, there is no further growth of the interdental papillae with respect to the
last contact point of the temporary crowns (25). An example of esthetic crown
lengthening limited to the buccal aspect and early restorative phase is shown in Figs 2–8.
An example of esthetic crown lengthening and early restorative phase is shown in Figs 9–
14.

44. Delayed tooth preparation and provisional
relining
 This approach is based on the concept of not interfering with
healing of the soft tissues (11). After the crown-lengthening
procedure, the margins of the provisional restoration are
maintained at the presurgical level until soft-tissue stability is
achieved (9–12 months). At this point, the final abutment
preparation is performed and the final prosthesis is delivered.

54. Conclusions
 Despite the fact that crown lengthening in esthetic areas is a widely used clinical procedure,
there is a lack of evidence in the literature regarding the description of both surgical and
prosthetic procedures. However, some indications can be summarized:
 The objective of resective surgery is to obtain an increase in the clinical crown length. To
achieve this, hard and soft tissues must be thinned as much as possible in order to minimize
the amount of supporting bone removal (ostectomy):
1) The surgical papillae should be elevated in a split-thickness manner.
2) The palatal flap should be elevated using the ‘thinned palatal flap approach’.
3) The nonsupportive bone should be thinned to obtain a precise flap adaptation.
4) The buccal ostectomy should be performed, after choosing the guiding tooth, following the
esthetic proportion parameters.

55.  Regrowth of soft tissue after the crown-lengthening procedure is dependent on
individual patient factors and the timing of the placement of the final restoration
should be chosen accordingly.
 The provisional prosthetic restoration phase should start 3 weeks after the surgery
in order not to interfere with the re-establishment of the biologic width and to
condition the soft tissues during the period of maximal regrowth. Figure 15
summarizes the staging of crown-lengthening prosthetic procedures.