Optimizing Surgical Approaches for Effective Crown Lengthening
Surgical treatment strategies for aesthetic crown lengthening depend on gingival thickness and crestal bone position. Understanding the variations between cases, such as the need for osseous reduction or flap repositioning, is crucial for achieving optimal functional and aesthetic outcomes.
Surgical treatment largely depends on the underlying etiology. Coslet et al1 identified multiple types and subcategories for altered passive eruption (APE) based on gingival thickness and crestal bone position. Type 1 has normal keratinized tissue width, while Type 2 has a narrow, but acceptable, band of buccal attached, keratinized tissue. In the A subgroup, the osseous crest is 1.5 to 2 mm below the cementoenamel junction (CEJ) (normal), while in the B subgroup, the osseous crest is at the CEJ.1
The different relations of the hard and soft tissues can alter the surgical plan. For example, patients presenting with Type 1B would benefit most from gingivectomy and osseous reduction to reestablish the appropriate biologic dimensions (where there is both excess gingival tissue and bone). Conversely, caution should be taken in treating Type 2B, where flap margins should simply be apically repositioned to minimize any mucogingival defects with tissue resection.
Certain principles are universal for esthetic and functional crown lengthening procedures. For example, an average of 1 mm of bone is removed during osseous-related surgery and generally stabilizes by six months.2 During healing, 0.54 mm of bone is generally lost, with thinner bone resorbing more quickly.3 While the desired distance from the planned restorative margin to crestal bone is 3 mm, the mean distance achieved by most clinicians is 2.4 + 1.4 mm. More experienced surgeons may remove larger amounts of bone, with generally greater osseous reduction on the buccal and mesial aspects.4
Flap management can affect short- and long-term healing. Newer evidence shows that flaps replaced less than 3 mm from bone after conventional osseous surgery were stable at six months 93% of the time. There is a linear relation between final flap margin position and posttreatment tissue rebound.5
Furthermore, dentists should wait at least six months after crown lengthening in the esthetic zone to finalize the prosthesis because 12% of treated sites exhibit anywhere from 2 to 4 mm recession. Soft tissue rebound can also still occur during initial healing. Provisionalization during this healing period can therefore help guide marginal tissue stability.6
References
- Coslet JG, Vanarsdall R, Weisgold A. Diagnosis and classification of delayed passive eruption of the dentogingival junction in the adult. Alpha Omegan. 1977;7:24–28.
- Pontoriero R, Carnevale G. Surgical crown lengthening: a 12-month clinical wound healing study. J Periodontol. 2001;72:841–848.
- Pennel BM, King KO, Wilderman MN, Barron JM. Repair of the alveolar process following osseous surgery. J Periodontol. 1967;38:426–431.
- Herrero F, Scott JB, Maropis PS, Yukna RA. Clinical comparison of desired versus actual amount of surgical crown lengthening. J Periodontol. 1995;66:568–571.
- Penner JK, Deas DE, Mills MP, et al. Post-surgical flap placement following osseous surgery: A short-term clinical evaluation. J Periodontol. 2020;91:501–507.
- Brägger U, Lauchenauer D, Lang NP. Surgical lengthening of the clinical crown. J Clin Periodontol. 1992;19:58–63.
This information originally appeared in Saltz AE, Antonella AB. Decision-Making in Esthetic and Functional Crown Lengthening. Decisions in Dentistry. March 2022;8(3)30-33.
