Correction of gummy smile: A report of two cases.

Cosmetically acceptable smiles show a gingival display of up to 3 mm. Gingival display of greater than 3 mm results in a gummy smile which is often unsightly for the individual and correction is sought. There are a variety of procedures used for surgical crown lengthening. Here, we describe two such cases requiring two different approaches for surgical crown lengthening.

INTRODUCTION

“Beauty lies in the eyes of the beholder” - keeping this old adage in mind, smile corrections can be done in patients with cosmetic concerns. What constitutes a pleasant smile varies from person to person, but usually depends on the extent of gingival exposure. When a person smiles, the entire crowns of maxillary central incisors and 1 mm of pink attached gingival is visible. An exposed gingiva of 2-3 mm is cosmetically acceptable. A gummy smile is seen usually when more than 3 mm of gingival is visible. The form of the lips and the position of lips during speech and smiling cannot be changed easily, but the dentist can modify/control the form of the teeth, interdental papilla, and position of the gingival margin and incisal edges of the teeth. While correcting the position of the marginal gingiva, one should be cautious in preserving the biologic width. Often, osseous recontouring becomes essential to maintain the integrity of the biologic width and enable proper margin placement. Various methods have been documented including gingivectomy, flap surgery with osseous contouring, apically displaced flaps, and orthodontic therapy. Excessive display of the gingiva is sometimes caused by vertical maxillary excess and a long mid-face. Surgical crown lengthening does not suffice in such cases and the maxilla has to be surgically treated with maxillofacial surgery. The risk-benefit and cost ratios must be thoroughly evaluated in such cases. An interdisciplinary approach is vital in such cases when the patient is unwilling for a major surgery. A combination of soft and hard tissue contouring with appropriate prosthetic restoration to alter the shape of the teeth achieves an aesthetic result, at least partially.

A classification system for aesthetic crown lengthening procedures has been proposed[1] by Lee.

Type I - sufficient soft tissue present allowing gingival exposure of the alveolar crest or violation of the biologic width. Corrective procedure may be performed by the restorative dentist. Provisional restorations of the desired length may be placed immediately.

Type II - sufficient soft tissue allows gingival excision without exposure of the alveolar crest, but in violation of the biologic width. These conditions will tolerate a temporary violation of the biologic width. Allows staging of the gingivectomy and osseous contouring procedures. Provisional restorations of the desired length may be placed immediately. Requires osseous contouring. May require a surgical referral.

Type III - gingival excision to the desired clinical crown length will expose the alveolar crest. Staging of the procedures and alternative treatment sequence may minimize display of exposed subgingival structures. Provisional restorations of desired length may be placed at second-stage gingivectomy. Requires osseous contouring. May require a surgical referral. Limited flexibility.

Type IV - gingival excision will result in inadequate band of attached gingiva. Limited surgical options. No flexibility. A staged approach is not advantageous. May require a surgical referral.

Pre-procedural assessment

Prior to developing a suitable treatment plan, it is essential to establish a complete and accurate assessement of the conditions with which the patient presents.

Reasons for seeking treatment;

Assessment of systemic health and habits;

Height and symmetry of face;

Thickness, length, and profile of lips;

Smile line;

Condition and dimensions of teeth;

Width of keratinized gingiva;

Gingival biotype; and

Facial and lingual bone levels, thickness of alveolar.

CASE REPORTS

Case 1

Surgical crown lengthening without osseous correction: A 33-year-old female patient with unaesthetic crowns on the maxillary anteriors, with localized periodontitis, and maxillary gingival excess resulting in a gummy smile reported to a consultant Prosthodontist for replacement of crowns [Figure 1]. A treatment plan involving surgical crown lengthening without osseous correction on account of the existing bone loss and consequent pockets, followed by replacement of the crowns was drawn up and presented to the patient. After obtaining approval of the treatment plan and informed consent, phase 1 periodontal therapy was performed to prepare the tissues for surgery. Four weeks later, the patient was recalled for surgery. Bone sounding was done [Figure 2] under anesthesia, before starting the excision, to clearly establish the position of the bone. Inverse bevel gingivectomy [Figure 3] was done, and the flap rose for debridement and curettage.

Figure 1

Pre-operative view

Figure 2

Bone sounding

Figure 3

Inverse-bevel gingivectomy

The flap was sutured back [Figure 4] and the original bridge was cemented in place, temporarily [Figure 5]. The patient was recalled after four weeks, and a new temporary bridge was cemented [Figure 6].

Figure 4

Crown lengthening complete

Figure 5

Original bridge cemented

Figure 6

New provisional bridge

Case 2

Surgical crown lengthening with osseous correction for gummy smile: A 30-year-old female patient reported to the clinic with a chief complaint of a gummy smile that was not acceptable aesthetically. On clinical examination, she was found to have a vertical maxillary excess, and was a candidate for orthognathic surgery. However, the patient was unwilling to go through a complicated surgical procedure involving hospitalization, and yet wanted her smile to be altered. Hence, she was given an option of compromised correction by doing surgical crown lengthening involving soft tissue as well as osseous correction along with prosthetic placement of venners. In [Figure 7], the preoperative view can be seen with a severe maxillary excess causing a gummy smile. A crevicular incision was made from distal of tooth number, 14 to 24, and mucoperiosteal flap was raised [Figure 8]. Osseous correction was then performed, keeping in mind the biologic width requirements using a large round diamond bur on an airotor [Figure 9]. The flap was sutured back in the same position. After six weeks of healing and allowing complete shrinkage, gingivectomy was performed with aesthetic contouring [Figure 10]. After eight weeks of healing, composite veneers were placed as provisional restorations [Figure 11].

Figure 7

Pre-operative view

Figure 8

Flap raised and bony crests revealed

Figure 9

Osseous recontouring complete

Figure 10

Gingival recontouring after six weeks

Figure 11

Composite veneers placed

DISCUSSION

There are two aspects to the crown lengthening procedure: Aesthetic and functional. In both cases, the surgical procedure is aimed at re-establishing the biological width, apically, while exposing more tooth structure. Biological width is the sum of the junctional epithelium and supracrestal connective tissue attachment. The average space occupied by the sum of the junctional epithelium and the supracrestal connective tissue fibers was found to be 2.04 mm.[2] Violation of biological width has been associated with gingival inflammation, discomfort, gingival recession, alveolar bone loss, and pocket formation.[3]

To have a harmonious and successful long-term restoration, a 3 mm sound supracrestal tooth structure between bone and prosthetic margins, which allows for the reformation of the biological width plus sulcus depth is advocated.[45] This can be achieved surgically (crown lengthening), orthodontically (forced eruption), or by a combination of both.

Patients that require aesthetic crown lengthening, however, frequently exhibit a high smile line. As a result, pressure is often placed on the restorative dentist to correct aesthetic deficiencies as early as possible, and maintain certain aesthetic standards throughout the treatment. However, conventional protocols require a waiting period of four to six weeks for sufficient healing of the attachment apparatus, prior to initiating restorative procedures.[6] Hence adequate length of time was allowed for healing in both the cases. The surfaces exposed due to crown lengthening will be displayed through the healing period until the provisional prosthesis can be fabricated or relined. The exposed areas may be limited to cemento-enamel junctions and varying amounts of root surface, but may also include the margins of previous restorations.

Crown lengthening can be limited to the soft tissues when there is enough gingiva coronal to the alveolar bone, allowing for surgical modification of the gingival margins, without the need for osseous recontouring (that is, pseudopockets in cases of gingival hyperplasia), as seen in case 1, which presented with periodontitis and bone loss. An external or internal bevel gingivectomy (gingivoplasty) is the procedure of choice in these cases.

The biological width has not been compromised, and, as a result, the soft tissue pocket is eliminated and the teeth exposed without the need for osseous resection. Unfortunately, the majority of cases will involve bone recontouring as well as gingival resection to accommodate aesthetics and function. This is a more delicate procedure that requires exposing root surface, positioning gingival margins at the desired height, and apically reestablishing the biological width.

The level of the alveolar crest must be determined prior to any considerations regarding aesthetic crown lengthening. Bone sounding is utilized to determine the thickness of the soft tissue layer and height and thickness of the alveolar bone. Bone sounding assists in determining the level of the alveolar crest, and thus, the need for osseous contouring.[7] The crown-lengthening procedure enables restorative dentists to develop an adequate zone for crown retention without extending the crown margins deep into periodontal tissues. After the procedure, it is customary to wait six to eight weeks before cementing the final restoration. In the aesthetic zone, a waiting period of at least six months is recommended before final impression.[89] This reduces the chances of gingival recession following prosthetic crown insertion, specifically if there is a thin biotype. It may be beneficial in these scenarios to compartmentalize the soft and hard tissue components of the crown lengthening procedure and stage them individually for treatment.

Complications

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 triangles’;

Root sensitivity;

Root resorption; and

Transient mobility of the teeth.

CONCLUSION

Gingival topography is a complex interplay of the underlying bony architecture and the size, form and position of teeth. The concept of modern day dental aesthetics places equal impetus on the “White” and “Pink” components, and a balance of the two is an essential ingredient in smile designing. Crown lengthening procedures are extensively and effectively used in achieving optimal aesthetics.