Crown Lengthening in the Aesthetic Zone

INTRODUCTION
An important synergy exists between periodontics and restorative dentistry. The gingival architecture plays a critical role in the development of proper tooth size, shape, and tooth-to-tooth proportion.1-3 An accurate understanding of the hard- and soft-tissue anatomy, as well as how they relate to restorative treatments, is vital in creating anterior dental aesthetics. A multidisciplinary approach is often required to achieve ideal results.1-3
     The functional and aesthetic requirements of restorative dentistry direct the periodontal component of treatment. Optimal aesthetic restorative results can be accomplished by performing delicate periodontal procedures. Clinical crown lengthening surgery can shape a hard-tissue foundation that will support a natural appearance in the soft-tissue architecture. In addition, clinical crown lengthening will provide sufficient amounts of tooth structure for ideal tooth preparation and restoration.4-6 This is very important, due to the detrimental effects of improper placement of restorative margins and violation of biologic width.7,8
     This article will discuss the principles of clinical crown lengthening surgery and present a case that demonstrates its benefits in the aesthetic zone.

CASE REPORT
Diagnosis and Treatment Planning

Figure 1. Preoperative view showing dark-colored teeth and a diastema between the central incisors. Figure 2. The diagnostic models showed the preoperative condition.
Figure 3. A diagnostic wax-up assisted in communicating the goals of the proposed treatment among everyone on the treatment team and also with the patient.

     A male nonsmoker, age 58 years, was referred by his general dentist for clinical crown lengthening of teeth Nos. 5 to 12. The patient's chief concerns were dark-colored teeth and the presence of a diastema between his central incisors (Figure 1). The teeth were found to have good periodontal support, and a broad zone of keratinized gingiva was evident. The general dentist sent detailed written instructions to increase the clinical crown length of teeth Nos. 5 to 12 between 2 and 3 mm. Diagnostic models and a diagnostic wax-up provided additional information (Figures 2 and 3).

Treatment Steps
Profound local anesthesia was obtained using 2% lidocaine with 1:100,000 epinephrine (AstraZeneca [DENTSPLY Pharmaceutical]). Initial incisions were made using a No. 15 (Bard Parker) scalpel blade from teeth Nos. 4 to 13. The incision line followed the requested instructions for the desired increase in clinical crown length. The excess gingiva was removed. A maxillary anterior frenectomy was also performed at this time (Figure 4).

Figure 4. An incision line was made following the general dentist's request. Figure 5. Osseous recontouring was done. A proper biologic width was established in order to ensure stable gingival margins.
Figure 6. Sutures placed to secure the gingival margins in the proper positions. Figure 7. All-ceramic crowns were placed. The final result of the treatment protocol described was highly aesthetic.

     Upon reflection of full-thickness mucogingival flaps, thick crestal bone levels in close proximity to the cemento-enamel junction (CEJ) were found (Figure 5). Crestal bone levels on the facial aspects of the teeth were recontoured to be approximately 3 mm from the CEJ. This was accomplished using a combination of rotary and manual instruments (a carbide round bur [Patterson Dental], and Ochsenbein back action chisel [Hu-Friedy]). To maintain the volume of interdental papillae, the interdental bone and gingiva was minimally treated (Figure 5). The gingival flaps were secured in the proper position using a continuous 4.0 chromic gut suture (Ethicon [Patterson Dental]) (Figure 6). No suture was required at the frenectomy site.
     A nonsteroidal anti-inflammatory analgesic for management of discomfort was prescribed. The patient was also instructed to take amoxicillin (875 mg) twice daily for 10 days, and to rinse twice daily with 0.12% chlorhexidine gluconate (Peridex [Procter & Gamble]) for one week.
      At the one-week postoperative appointment, the sutures were removed. The patient was instructed on how to perform excellent oral hygiene and was to return to his general dentist for provisionalization as soon as possible.
      The patient returned to the general dentist for placement of provisional restorations 2 weeks following surgery and the initial healing phase. At the 12-week postoperative appointment, the surgical site appeared to have healed well and was free of inflammation. Little change in the position of the gingival margins appeared to have occurred from the time of placement of the provisional crowns. Impressions were taken at this appointment. Four weeks later, all-ceramic crowns were placed on teeth Nos. 6 to 11.
      Approximately 8 weeks after delivery of the final restorations, the patient was seen for re-evaluation (Figure 7). The gingiva appeared healthy with natural-appearing contours, and the overall appearance was highly aesthetic.

DISCUSSION
The first steps in any treatment plan must include a proper diagnosis and an understanding of the patient's concerns. Aesthetic perceptions between dentists and laypeople can vary.9 In this case, the patient's chief concern was dark appearing teeth and the diastema between teeth Nos. 8 and 9.
      From a restorative perspective, closing the diastema while maintaining ideal or golden tooth proportions was an important goal.10 Clinical crown lengthening would provide apical movement of the gingival margin to permit proper tooth preparation and creation of desired tooth height to width ratios.11 Detailed instructions, including diagnostic models, were given by the restorative dentist to indicate the amount of tooth exposure and gingival contours that were necessary to achieve his goals. The diagnostic wax-up model shows correction of the tooth shape, tooth rotations, and closing the diastema. The need for apical positioning of the gingival margin to permit creation of proper tooth proportion is evident. In cases like this, diagnostic models (including the diagnostic wax-up), are very useful in doctor-doctor, doctor-patient, and doctor-laboratory communication. They are also used to verify that the clinician's and patient's expectations are the same.
      From a periodontal perspective, clinical crown lengthening involves removal of hard and soft periodontal tissues to gain supracrestal tooth length and the re-establishment of the biologic width.12 The histologic description of the dentogingival complex by Gargiulo, et al13 lead to the concept of biologic width. The mean sulcus depth was 0.69 mm. The epithelial attachment was 0.97 mm. The connective tissue attachment was 1.07 mm. The total of these mean lengths yields a 2.73 mm biologic width. With these dimensions in mind, the crestal bone was moved to position approximately 3 mm from the newly established gingival margin.14
     Careful management of the interdental papillae area was also very important. Tarnow, et al15 found that the interdental papillae filled the embrasure space 98% of the time when the distance from the interproximal contact to the crestal bone was 5 mm or less. If this distance increased by only one mm, an interdental papillae that filled the embrasure space was present only 56% of the time. In order to minimize the risk of blunting of the interdental papillae, no bone supporting the interdental papillae was removed.
      High quality provisional restorations are a critical element in the aesthetic results of clinical crown lengthening. Provisional restorations with proper margins and emergence profiles will help establish gingival health and aesthetics.1,2 If no surgical or prosthetic refinements are required, final impressions can be taken after 3 months of healing. Lanning, et al12 found the position of the free gingival margin, attachment, and bone levels remained stable between 3 and 6 months. They did note, however, healing must be closely monitored and that positional changes could occur beyond 6 months.

CONCLUSION
A multidisciplinary approach is often necessary to achieve ideal aesthetic results. Clinical crown lengthening provides additional tooth structure for restoration and creates a foundation for an attractive, natural-appearing smile.

Acknowledgment
The author would like to thank Jerome Granato, DDS, for delivering the excellent restorations.


References

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  15. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992;63:995-996.

Dr. Mahn is a periodontist in private practice in Manassas, Va. He graduated from State University of New York Stony Brook Dental School in 1990 and completed his periodontal residency at the Medical College of Virginia School of Dentistry in 1992. He also completed a residency on temporomandibular disorders/orofacial pain at New York University College of Dentistry in 1996. Dr. Mahn's practice emphasizes perioplastic, regenerative, and dental implant therapies. He has several publications and has lectured on these topics. He can be reached at (703) 392-8844 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Disclosure: Dr. Mahn reports no disclosures.

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