Effect of free gingival graft dimension on postsurgical shrinkage in posterior implant placement: A prospective parallel cohort study.

Statement of problem: The impact of free gingival graft (FGG) dimensions on the postsurgical shrinkage of keratinized tissue width (KTW) and surface area in posterior implant sites is unclear. Standardized assessments of how graft dimensions influence KTW and surface area shrinkage rates over a 6-month period after FGG are lacking.

Purpose: The purpose of this prospective parallel cohort study was to examine the impact of the graft dimensions on the postsurgical shrinkage of KTW and surface area over a 6-month follow-up period after FGG in the posterior regions.

Material and methods: Thirty partially edentulous participants with insufficient buccal KTW in the posterior regions were recruited. Before implant placement, participants received FGG procedures and were categorized into single-tooth and dual-tooth groups according to the range of recipient area. Intraoral scanning was performed before and after FGG and at subsequent follow-ups for 6 months. The KTW and surface area shrinkage rates of the grafted area were calculated and statistically analyzed by using the Student t test and ANOVA, and Bonferroni post hoc tests were performed to compare the shrinkage rate of KTW at various edentulous sites (α=.05).

Results: The mean ±standard deviation KTW shrinkage rate was 18.84 ±5.11% over 6 months postoperatively, and the mean ±standard deviation SA shrinkage rate was 21.53 ±5.70%. The dual-tooth group had a statistically significantly higher KTW shrinkage rate (28.42 ±2.46%) when the second molar edentulous sites were involved (P<.05). Differences in surface area shrinkage rates between the single-tooth and dual-tooth groups over 6 months were statistically similar (P=.239). However, grafts in the second molar area exhibited significantly higher surface area shrinkage rates compared with those at the premolar and first molar areas (P<.001).

Conclusions: The dimension of free gingival graft tissues did not significantly affect surface area shrinkage rates, and a mean 25% shrinkage rate occurred in the second molar areas.