Crown lengthening: A surgical flap approach
Several papers have suggested that to assure a healthy periodontium, the physiologic dimensions of a minimal biologic space should not be violated. Many authors have suggested a 3-4 mm space should exist between the crest of bone and the restoration margin. This article discusses indications and contraindications for surgical crown lengthening (CL) procedures and presents a surgical technique.
The indications for CL include caries that approaches the periodontal attachment, fractures, endodontic perforations, cervical root resorption, retention of a prosthetic crown, and adequate access for an impression of a subgingival margin and to enhance esthetics in the case of short clinical crowns.
The contraindications for CL include the removal of tooth-supported bone that results in poor crown root ratios of not just the concerned tooth but also the adjacent teeth, furcation exposures, esthetic concerns of maxillary anterior teeth in high smile lines, intrusion of vital anatomic landmarks such as the sinus, cost, the patient psychology of bone removal, poor oral hygiene, and medical considerations.
The surgical procedure's first incision on the facial extends one or two teeth anterior to one or two teeth posterior to the tooth being crown lengthened. The incision depth depends upon the quantity of bone removal necessary and the width of existing keratinizing tissue. The incision may be scalloped for more rapid healing and comfort. Vertical releasing incisions may be necessary to enhance visibility and to avoid exposing porcelain crown margins. The vertical incisions should not be placed over the roots because of the probability of root recession. The second incision is made into the sulcus to sever the supracrestal soft tissue attachment. The third incision is made at the base of the interproximal gingival papillae in the area being treated to sever the papillae off of its alveolar base.
The three incisions are repeated on the palate, with the initial incision possibly more than the usual 1-2 mm from the gingival margin because the palatal tissue is not capable of being apically repositioned. Full-thickness facial and lingual flaps are reflected to obtain sufficient alveolar bone exposure to perform osseous resection. Enough bone is removed to create a 3 mm space between the anticipated location of the apical margin of the restoration and the surgically reduced apical crest. The faciolingual width of the interproximal septal bone is narrowed, which reduces interproximal bone bulk. The facial and lingual tooth-supported alveolar plates are thinned, shaped, and blended to recreate a normal alveolar architecture at a slightly more apical location. A Rhodes back- action chisel is excellent for blending the bone and removing thin rims of bone left around the roots. A Schluger file is used to thin and reduce the interproximal septal bone so there is a 3 mm space between the proposed restoration and the bone.
The final position of the gingival margin may not be stabilized for a year. Where this location is a consideration, it is prudent to wait at least six months before proceeding with the final restoration. [C.S.]
Lundergan, W., and W. Hughes, Compendium, 17:833, 1996