Written by Michael J. Rechter, DDS, and Alexander Corsair, DMD Thursday, 28 February 2002 19:00
Chiche and Pinault1 describe in their text, Esthetics of Anterior Fixed Prosthodontics, the artistic and scientific principles applied to aesthetic dentistry. “Four factors of esthetic composition applied to the smile are: (1) frame and reference, (2) proportion and idealism, (3) symmetry, and (4) perspective and illusion.” Some cases of “gummy smile” or excessive display of gingiva present with a lack of facial proportion, requiring orthodontic treatment and/or orthognathic surgery in order to achieve ideal dental and facial aesthetics. Other cases are treatable with periodontal surgical crown lengthening and prosthetic restoration.
The face, lips, and gingiva frame the teeth. In the ideal smile the cervical aspects of the maxillary canines and central incisors barely touch the border of the maxillary lip. The lateral incisors may also touch the maxillary lip, or may be 1 to 2 mm coronal to the lip border, revealing some gingiva. Patients may reveal excessive gingiva for several reasons: short crowns as a result of altered passive eruption, extruded teeth, a concave hyperactive maxillary lip, or a maxillary protrusion. An orthodontic consultation may show that the patient has excessive vertical dimension of the lower half of the face (from subnasion to gnathion), as well as excessive dental overbite. Should the deviation from ideal be 5 mm or more, orthognathic surgery may be required to achieve an ideal aesthetic result. This is especially true when there is an anterior open bite2 and minimal incisal reveal (short incisor-stomion distance). If the facial proportions are within normal limits but the extent of the overbite is excessive and the incisal reveal is greater than 4 mm (distance from lower border of the maxillary lip to the incisal edge), then excessive gingival display may be corrected by orthodontic treatment alone (intrusion of the anterior teeth with concomitant apical movement of the gingival margins).3 On the other hand, if the facial proportions are acceptable but the maxillary anterior teeth are short and require restoration, then aesthetic surgical crown lengthening may be the best alternative.
Short maxillary anterior teeth may be the result of attrition, which can lead to extrusion with excessive gingival display. Short teeth may also result from altered or delayed passive eruption. In a fully erupted tooth the gingival margin is located on the enamel 0.5 to 2 mm coronal to the CEJ. In the earlier stages of eruption the gingival margin is located more coronally and gradually moves apically until eruption is completed. This is called passive eruption. Failure of this to occur is called delayed passive eruption.4 This results in a short clinical crown(s) and may be expressed as a “gummy smile” in a patient with a short or hyperactive lip, or in a patient with vertical facial excess or a deep overbite with extrusion. Passive eruption is usually completed at age 24 ± 6.2 years. Twelve percent of patients exhibited delayed passive eruption in a study by Volchansky and Cleanton-Jones.5
A proper diagnosis and treatment plan is arrived at after collecting diagnostic data from mounted study models, photos, and radiographs. Data should include existing crown length, crown-to-root ratio, probing depths, amount of attached gingiva, extent of overjet, and phonetic considerations. Data should also include the degree of overbite, the extent of gingival display, and the extent of incisal reveal at rest and when smiling. The patient and dentists need to agree on the desired and predicted extent of gingival and incisal reveal.
The simplistic idea of making teeth longer so less gingiva is revealed can be fraught with problems, such as making teeth too long (width to length ratio should be 8:10 for the incisors), losing the papilla, and exposing root structure without a restorative commitment to correct this problem.
Once the diagnostic data have been reviewed, the periodontist and the restorative dentist must make several determinations. What will be the best crown length for this patient? Where will the incisal edges be located? In some cases, particularly if the incisal edge position is not going to be changed, one may simply make measurements with a boley gauge of the pre- and intended postsurgical crown length. In many cases, placement of provisional crowns should precede surgery. The use of a surgical stent, made of composite or vacuum formed, can serve as a guide for the surgeon in determining the new cervical location of the gingival and osseous margins.
In a small number of cases, the required amount of crown lengthening can be accomplished with simple gingivectomy. This would only be true in a case where abundant attached keratinized gingiva is present, and the gingival margins are a distance from the CEJ equal to the amount of lengthening required plus 3 mm. This could occur in some cases of delayed passive eruption. In most cases, crown lengthening requires a flap and osseous resection. Patients present with supracrestal gingiva (the soft tissue from the osseous crest to the gingival margin) that usually measures 3 mm on the facial. This is an average based on the research of Gargiulo and others.6 Kois7 and others have advocated bone sounding (probing to the bone crest after administering anesthesia) to determine if a particular patient has a high or low bone crest. This is a helpful procedure because the location of the osseous crest relative to the gingival margin (or the extent of supracrestal gingiva) may vary from tooth to tooth or patient to patient. The recent work of Oakley et al8 has shown, however, that if the exposed roots are planed after bone has been resected, the connective tissue will be maintained in an apical position occupying no more than 2 mm (plus a 1- mm crevice = 3 mm of supracrestal gingiva). These concepts apply to functional crown lengthening as well.
This article presents a case demonstrating a multidisciplinary approach to correction of an aesthetic problem that involved excessive exposure of gingiva, in combination with other aesthetic problems.
|Figure 1. Preoperative facial view. Poor crown margins.||Figure 2. Preoperative portrait view. Excessive display of gingiva is apparent.|
A 37-year-old female patient presented to discuss her dissatisfaction with her smile. During the last 15 years, crowns had been placed and then replaced on teeth Nos. 8 and 9. The patient was still unhappy with the appearance of the central incisors. She was conscious of the unsightly gingival margins of the existing porcelain-fused-to-metal crowns and the incorrect size of the central incisors relative to the other anterior teeth (Figure 1). This was compounded by a very broad smile that displayed an excessive amount of gingiva (Figure 2) with inadequate buccal corridors bilaterally and a missing tooth in the No. 13 area. In addition, the buccal flare of the central incisors was overly prominent and lacked contour.
The buccal corridor is the space between the buccal mucosa and the facial surfaces of the teeth, from the bicuspids posteriorly. When no teeth in this area are present, or if the teeth are lingually inclined, this area may appear dark. It is often referred to as “negative space.” When these corridors are filled with teeth, they will improve lip support, broaden the smile, and give a more youthful appearance. Diagnostically, it is important to determine how many teeth are displayed in a broad smile, as this will determine the number of teeth to be included in the treatment plan. Building out the buccal surfaces of the posterior teeth that are displayed will create a positive buccal corridor.
|Figure 3. Pretreatment planning.|
During the initial consultation it is important to introduce the concept of a comprehensive cosmetic approach. Only replacing the central incisors would not correct the aesthetic problems. The patient was seen for a thorough evaluation including a review of the medical history, oral cancer examination, and an evaluation of the periodontal status and restorative needs. A full-mouth series of radiographs, study models, 35-mm photos (Lester Dine) and cosmetic imaging photos (Smile Vision) were taken and utilized for diagnosis and treatment planning (Figure 3).
A team approach was employed to ensure the best long-term result. A referral to the periodontist was made, and the case was discussed with the laboratory technician.
Logistically, the concerns which needed to be addressed included the effect of the metal posts associated with teeth Nos. 8 and 9, the restoration of the narrow edentulous space in the No. 13 area, and the excessive display of gingiva (“gummy smile”).
The position of the incisal edges of the teeth was the starting point and would affect length, golden proportion, and height of the gingival margin. Golden proportion is the tooth-to-tooth size ratio from the central incisor to the mesial aspect of the canine. Leven9 states that the maxillary central incisor should be 60% wider than the lateral incisor, and that the lateral incisor should be 60% wider than the canine from its midline to its mesial aspect. If the lateral incisor is assigned a value of 1, the central incisor should be 1.6 times the width of the lateral incisor. The width of the mesial aspect of the canine should be 0.6 times the width of the lateral incisor. In addition, the correct width-to-length ratio of the central incisor should be 75% to 85%.
|Figure 4. Composite overlay illustrating proposed tooth length.|
Based on testing phonetics (“E” and “F” sounds), it was determined to keep the incisal edge in its original position. The length of the central incisors was about 10 mm, which allowed lengthening at the gingival aspect by 1.5 mm. This was confirmed visually by tacking composite on the gingiva and asking the patient to go through a series of broad smiles to observe the change in appearance (Figure 4). From this point the golden proportion could be determined, and surgical crown lengthening was determined to be feasible.
It was also decided that the use of Procera crowns would allow masking of the metal posts of teeth Nos. 8 and 9 and matching with teeth Nos. 5 through 7 and Nos. 10 through 12, which would be treated with porcelain veneers.
Posteriorly, it was felt that a cantilever bridge (Nos. 13 through 15) would be the best option to close the No. 13 space. Teeth Nos. 3 and 4 would be treated with full porcelain crowns. Tooth No. 2 was not treated.
Prior to beginning restorative treatment of the maxillary arch, a limited occlusal adjustment and enameloplasty of the mandibular anterior teeth were performed. This improved aesthetics by eliminating small irregularities. For both the maxillary and mandibular teeth, bleaching (Brite Smile) was accomplished to improve the tooth shade from A3 to A1.
The existing crowns on Nos. 8 and 9 were removed, and temporary crowns were placed using Luxatemp A1 (Zenith) and a Siltec putty tray which incorporated ideal tooth form because it was fabricated using a diagnostic wax-up on the study model as a template. The temporary restorations were adjusted to establish the proper incisal edge because the periodontist would be using this landmark for proper tissue placement. The patient was then referred back to the periodontist.
When smiling, the display of gingiva was excessive, especially apical to teeth Nos. 10 and 11 and to a lesser degree for No. 7. The surgical plan was to remove gingiva (and alveolar bone) to maintain 3 mm of supracrestal gingiva. Teeth Nos. 6, 8, 9, and 11 were to be 11.5 mm in length. Teeth Nos. 7 and 10 would be 9.5 mm in length. This meant removal of 1.9 mm of bone for No. 11, 1.5 mm for No. 6 and No. 9, 1.2 mm for No. 10, 1 mm for No. 8, and 0.5 mm for No. 7. The surgery would create symmetry from the midline to the cuspid teeth. The length-to-width proportion of the central incisors would also be improved since prior to surgery these teeth were short.
|Figure 5. Resection of excess gingiva.||Figure 6. Full-thickness flap elevated and ostectomy completed.|
|Figure 7a. Flap closed with silk sutures.||Figure 7b. The new gingival margins of the cuspids and central incisors now contact the inferior border of the maxillary lip.|
The restorative dentist prepared a stent for the periodontist. After administration of local anesthesia, the stent and a boley gauge were used to place points on the gingiva marking the new gingival margins (Figure 5). The internally beveled incision traversed the base of the papilla and resected marginal gingiva on the facial, as planned, from the distal of tooth No. 6 to the distal of tooth No. 11. An adequate extent of gingiva was present so that the resection would not result in a mucogingival defect. A full thickness mucoperiostal flap was elevated to expose the osseous crest. Vertical incisions were not used. Bone was then removed to create 3 mm of supracrestal gingiva. Osseous removal was accomplished with round diamonds (Brasseler 023 and 018) and curettes (Columbia 4R4L by Hu Freidy). The roots were planed to prevent regrowth of connective tissue (Figure 6). The flap was replaced and the new gingival margins were evaluated for position, symmetry, and relationship to the occlusal plane and the interpupillary line. The flaps were closed with 4-0 silk sutures (Figures 7a and 7b). The patient was given a prescription for tetracycline hydrochloride 250 mg qid for 5 days, and acetominophen and 30 mg codeine for postoperative pain. The patient was seen 7 days later for suture removal and review of postoperative care. After several postoperative visits she was referred back to her restorative dentist.
|Figure 8. Teeth are prepared.||Figure 9a. Temporary restorations, patient smiling.|
|Figure 9b. Temporary restorations, retracted view.|
The teeth were then prepared using a variety of Brasseler depth-cutting and crown and bridge burs (Figure 8). An Impregum (3M ESPE) impression was taken, as well as a cross-haired stick bite using President Jet (Coltene) bite material. A cross-haired stick bite uses two microbrush handles, one placed parallel to the interpupillary line, and the other placed vertically to establish the proper midline. These are incorporated into the bite registration, thus enabling the laboratory technician to verify correct midline and cant of the teeth. A face-bow transfer was also utilized. Temporary restorations were placed, with concern for margin adaptation and contour. The patient was asked to return 3 days later for observation and any final aesthetic concerns. After the patient approved the provisional restorations/aesthetic plan, photos, study models, and an incisal guide of the provisional restorations in the mouth were taken and sent to the laboratory (Figures 9a and 9b).
|Figure 10a. Final result, portrait.||Figure 10b. Final result, close-up.|
Three weeks later the restorations for teeth Nos. 13 through 15 were cemented with Ketac (3M ESPE), and the remaining porcelain restorations were bonded using Variolink (Ivoclar Vivadent) translucent. Under rubber dam isolation a rapid cementation technique was utilized whereby all teeth except Nos. 8 and 9 were inserted simultaneously with Variolink base only. This allowed ample working time to load veneers with cement, seat, and remove excess without a concern for premature setting. Once each veneer was in place, that restoration was spot light cured for 3 seconds. At this time all contacts were cleared with a Brasseler separating saw, and Nos. 8 and 9 were then inserted using Variolink base and catalyst. All teeth were then light cured using the Optilux 401 (Demetron) bonding light. Contours and occlusion were adjusted after removal of the minimal excess flash. The patient returned 1 week later for final adjustments and postoperative photographs (Figures 10a and 10b).
Innovations in periodontal therapy have enabled the periodontist, working with the restorative dentist, to correct problems of anterior aesthetic symmetry and proportion by adding or removing gingiva. However, proper collection of data and formulation of an appropriate treatment plan is the key. Contraindications to aesthetic surgical crown lengthening for a smile displaying excessive gingiva include medical contraindications to surgery, inadequate periodontal support, teeth that are long with little overbite, facial disharmony requiring orthodontics and/or orthognathic surgery, lack of commitment to the required restorative dentistry, and unrealistic patient expectations.
Successful completion of a comprehensive cosmetic treatment plan requires a multidisciplinary approach involving the restorative dentist, periodontist, and laboratory technician. Communication among all professionals, as well as concern for patient desires, are essential to achieve an ideal result.
The authors would like to thank Adrian Jurim of Jurim Dental Lab for the laboratory procedures performed in the case presented.
1. Chiche CJ, Pinault AP. Esthetics of Anterior Fixed Prosthodontics. Chicago, Ill: Quintessence Publishing Co; 1994.
2. Legan HL, Hill SC, Sinn DP. Sugical-orthodontic treatment of dentofacial deformities. Dent Clin North Am. 1981;25:131-156.
3. Nanda R. The differential diagnosis and treatment of excessive overbite. Dent Clin North Am. 1981;25:69-84, 1981.
4. Ainamo J, Loe H. Anatomical characteristics of gingiva. J Periodontol. 1966;37:5-13.
5. Volchansky A, Cleanton-Jones P. The position of the gingival margin as expressed by clinical crown height in children aged 6-16. J Dent. 1976;4:116-122.
6. Gargiulo AW, Wentz FM, Orban, B. Dimensions and relations of the dentogingival junction in humans. J Periodontol. 1961;32:261-267.
7. Kois JC. Altering Gingival levels: the restorative connection, part 1: biologic variables. J Esthet Dent. 1994;6:3-9.
8. Oakley E, Rhyu IC, Karatzas S, et al. Formation of the biologic width following crown lengthening in nonhuman primates. Int J Periodont Rest Dent. 1999;19:529-541.
9. Leven EL. Dental esthetics and the golden proportion. J Prosthet Dent. 1978;40:244.
Dr. Rechter currently practices general dentistry in Rockville Centre, NY. He can be contacted at (516) 766-0122.
Dr. Corsair limits his practice in Rockville Centre, NY to periodontics and implant surgery. He is also an assistant clinical professor of periodontology at SUNY, Stony Brook. He is a diplomate of the American Board of Periodontology. He can be contacted at (516) 536-3366.
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