Determinants of keratinized mucosa dimensional changes after apically positioned flap surgery around dental implants

This study aimed to evaluate changes in keratinized mucosa width (KMW) following an apically positioned flap (APF) during implant placement and to identify factors associated with KMW gain (KMWG).

This retrospective single-center study included patients who underwent APF during implant placement. KMW was measured at baseline (BKMW), immediately after surgery (T1), and at 6 months after surgery (T2). Clinicodemographic and surgical factors were recorded, and univariable and multivariable generalized estimating equation (GEE) analyses were performed to identify factors associated with KMWG.

This study included 78 patients with 207 implants. The mean BKMW was 1.09±1.54 mm, the mean T1 was 4.59±2.29 mm, the mean T2 was 2.71±1.70 mm, and the mean KMWG was 1.62±1.46 mm. In univariable GEE analysis, hypertension, periodontal phenotype, BKMW, and the amount of flap displacement (AFD) were associated with KMWG (P<0.05). In multivariable GEE analysis, hypertension (estimate=0.607, P=0.012), periodontal phenotype (estimate=0.603 for thick phenotype, P=0.014), and AFD (estimate=0.221, P=0.018) were positively associated with KMWG, whereas BKMW was negatively associated with KMWG (estimate=-0.349, P<0.001).

An increase in peri-implant KMW was observed after APF performed during implant placement. Clinicodemographic and surgical factors were associated with KMWG, suggesting that preoperative assessment may improve the predictability of peri-implant soft tissue augmentation and support surgical planning. Clinically meaningful KMWG could be achieved even with relatively limited flap extension when APF was performed using a standardized surgical approach.