Surgical crown lengthening: A 12-month clinical wound healing study

Background: Surgical crown lengthening has been proposed as a means of faci litating restorative procedures and preventing periodontal injuries in teet h with structurally inadequate clinical crowns or exposing tooth structure in the presence of deep, subgingival pathologies which may hamper the acces s for proper restorative measures. The few clinical studies in the current literature on postsurgical soft tissue modifications after crown lengthenin g procedures report conflicting results. The present study was designed to assess the alterations of the marginal periodontal tissues as an immediate outcome of surgical crown lengthening and over a 12-month healing period. Methods: The patient sample included 30 patients (84 teeth) who presented w ith various conditions hampering proper restorative measures in one or more teeth and, therefore, requiring surgical exposure of tooth substance. Afte r initial supportive therapy, the patients were recalled for a baseline exa mination, and the following parameters were evaluated at interproximal and buccal/lingual sites of each experimental tooth: plaque index, gingival ind ex, position of the gingival margin, probing depth, and attachment level. A fter baseline examination, the patients underwent apically positioned flap surgery with osseous and connective tissue attachment resection. During sur gery, the amount of resection and the achieved lengthening of the clinical crown were evaluated. The patients were enrolled in a maintenance program i ncluding professional tooth cleaning every 2 to 4 weeks. The patients were reexamined 1, 3, 6, 9, and 12 months postoperatively. Results: 1) Immediately after surgery, a significantly (P <0.001) increased clinical crown length of 3.7 +/- 0.8 mm (mean) at interproximal and 4.1 +/ - 0.9 mm (mean) at buccal/lingual sites was achieved; 2) healing resulted i n a statistically significant coronal displacement of the gingival margin o f 3.2 +/- 0.8 mm at interproximal (P <0.001) and 2.9 +/- 0.6 mm at buccal/l ingual (P <0.002) sites; and 3) as a consequence of this postsurgical soft tissue regrowth, the amount of the available tooth structure immediately af ter surgery decreased to 0.5 +/- 0.6 mm at interproximal sites (P <0.0015) and to 1.2 +/- 0.7 mm at buccal/lingual sites (P <0.001) at the 12-month ex amination. Conclusions: The results of the present clinical investigation demonstrated that during a 1-year period of healing following surgical crown lengthenin g, the marginal periodontal tissue showed a tendency to grow in a coronal d irection from the level defined at surgery. This pattern of coronal displac ement of the gingival margin was more pronounced (P <0.001) in patients wit h "thick" tissue biotype and also appeared to be influenced by individual v ariations in the healing response (P <0.001) not related to age or gender.