Influence of Restorative Timing on Crown Lengthening Outcome.

Setting the restorative margins for teeth with short clinical crowns is challenging and crown lengthening surgery (CLS) is often necessary. The aim of this study was to assess the influence of prosthetic restorative treatment timing on gingival margin location of teeth after crown lengthening surgery.

Eighteen patients requiring CLS were enrolled in the study and divided into two groups depending on the timing of prosthetic rehabilitation, at 6 or fourteen weeks after CLS.Clinical parameters were recorded around treated and neighboring teeth with adjacent and non-adjacent sites at 6 and 14 weeks after surgery as well as three and six months after prosthesis delivery. Alveolar ridge changes were assessed via digital X-rays.Soft tissue healing and the final treatment outcome were assessed by both patients and prosthodontists.

Twenty patients selected from those referred to the Department of Periodontics for crown lengthening surgery were enrolled in the study (9 females, 11 males, 19-65 years old, mean age:45.2) Patients were randomly assigned to one of the two experimental groups. For the first group of patients (A), prosthetic restoration started 6 weeks whereas for the second group (B)14 weeks after surgery. After recording of pre-surgical measurements, intrasulcular or internal bevel incisions were performed buccally and lingually, and full-thickness mucoperiosteal flaps were raised. Buccal flaps were reflected to a level beyond the mucogingival junction. The osseous crest and subgingival tooth structure were exposed. The osseous resection was performed after considering the amount of additional tooth structure required for restorative purpose and the preoperative Supracrestal Tissue Attachment at each site with hand and rotary instruments in a manner of establishing positive bone architecture. After root planing, suturing of the surgical sites was performed. The flap margins were placed at or apical to the anticipated crown margin after suturing and as far from the osseous crest as possible and necessary postoperative instructions were given. Patients were recalled 1 week post-surgery for suture removal, oral hygiene reinforcement and healing assessment. Healing was also evaluated at the end of the second post-operative week. All patients were reevaluated at 3 and 6 months after the prosthesis delivery.

Eligibility Criteria:
Inclusion Criteria:

* age ≥ 18 years,
* periodontally healthy or periodontally treated subjects with Plaque scores ≤15% \& GI ≤15%
* each patient could participate with one tooth only,
* non-smokers or smokers of less than 5 cigarettes per day,
* target tooth should be surrounded by both the adjacent teeth which should not be restored,
* provisional and final prosthetic margins should not extend subgingivally,
* in case of fracture this should be radiographically detectable,
* if a root canal treatment was necessary it should have been completed at least 6 months earlier.
* both anterior and posterior teeth included.

Exclusion Criteria:

* the presence of syndromes affecting bone metabolism,
* any kind of contraindication for periodontal surgery,
* pregnancy or lactation,
* no compliance with re-examinations or oral hygiene performance
* cases where gingivectomy or apically repositioned flap without osseous resection were indicated