Biologic Width Following Different Crown Lengthening Procedures: A Six-Month Follow-Up Study

Abstract

Background: One of the important things to preserve during crown lengthening is the biologic width (BW), recently called supracrestal tissue attachment. A healthy periodontium with adequate BW is very essential for the success of restored teeth. There are various techniques to perform crown lengthening procedures. Most of the studies have focused on assessing the changes in the position of the marginal gingiva and bone as outcome parameters rather than BW. Also, most of the research was done on animal models.

Aim: The purpose of this study was to assess the periodontal tissue changes at three months and six months following two different surgical crown lengthening procedures.

Materials and methods: Sixty mandibular first molars among 60 patients that required surgical crown lengthening were enrolled in the study and subjected to two different procedures, gingivectomy (Group I; n=30) and apically positioned flap with ostectomy (Group II; n=30). The following parameters were recorded at baseline, three months, and six months, position of free gingival margin (FGM), probing depth (PD), relative attachment level (RAL), bone level (BL), and BW. These measurements were made at three sites in every patient: treated tooth sites (TT), adjacent tooth's adjacent sites (AD), and adjacent tooth's non-adjacent sites (NAD). The data was then subjected to statistical analysis using SPSS software (Version 20.0). Statistical significance was set to p<0.05.

Results: When groups I and II were compared at three and six months, there was no statistical difference in terms of position of FGM, PD, and RAL (p>0.05). When BW was compared between the two groups at three and six months, group II showed better reestablishment of BW at any given time period and was statistically significant (p<0.05).

Conclusion: Following surgical crown lengthening, the bone level was shifted apically and allowed for the reestablishment of BW. At six months of follow-up, the apically positioned flap with ostectomy was superior in restoring the BW compared to gingivectomy.

Keywords: apically displaced flap; biologic width; crown lengthening; gingivectomy; osseous reduction.

Figure 1. (a) Pre-operative image showing inadequate crown height in relation to 36; (b) intra-operative image showing crown lengthening procedure by gingivectomy

Figure 2. (a) Pre-operative image showing inadequate crown height in relation to 36; (b) intra-operative image showing crown lengthening procedure by apically displaced flap with osseous reduction