Pre-restorative crown lengthening surgery outcomes: a systematic review.

Background: Pre-restorative crown lengthening surgery (CLS) is a common periodontal procedure, for which systematic reviews are lacking. This systematic review aimed to assess outcomes of CLS performed for restorative reasons.

Methods: Databases (MEDLINE, Scopus, OpenGrey) were searched up to January 2016 for clinical/animal trials on CLS for restorative reasons with ≥6-month follow-up. Primary outcomes investigated were: free gingival margin position, probing depth, clinical attachment level, and plaque/inflammation indices.

Results: Four non-randomized and one randomized controlled clinical trial and one controlled animal trial were included. Heterogeneity and high risk of bias were identified. CLS resulted in increased crown length (6-month average: 1.4-3.3 mm). Between immediate postsurgery and follow-up, gingival margin may rebound, largely during the first three postoperative months. Technical (flap positioning, osseous resection, root preparation) and anatomical (periodontal biotype) factors influence outcomes. The literature lacks studies on tooth mobility, crown-root ratio, patient- and referring dentist-reported outcomes, surgical technique comparisons, and restorative treatment timing.

Conclusions: Within the available data limitations, it is concluded that CLS results in increased crown length and possible gingival margin rebound. Technical aspects (primarily) and anatomical factors (secondarily) influence outcomes. Future research is needed to fill significant voids in our knowledge on several procedural aspects.