Effectiveness of keratinized mucosa augmentation procedures around dental implants based on risk assessment: A 5-year retrospective cohort study

Purpose: To compare the effectiveness of keratinized mucosa (KM) augmentation with different techniques for the treatment of dental implants based on risk assessment. Methods: Thirty-nine patients who underwent KM augmentation at implant sites in the posterior mandible were included. Three techniques were used based on anatomy-guided risk assessment: an apically positioned flap (APF) alone, an APF plus a free gingival graft (APF plus FGG), and an APF plus a collagen matrix (APF plus CM). Clinically effective KM augmentation was defined as remaining KM >= 2 mm after the intervention. The effective rate, implant/prosthesis survival rates, and bone/soft tissue parameters were analyzed. The correlation between local anatomical characteristics and different techniques was also determined. The associations between the effectiveness of KM augmentation and related factors were analyzed using a linear model. Results: Overall, 74 sites received KM augmentation in the posterior mandible, for an effective rate of 94.6% at the 1-year follow-up and 93.2% at the 5-year follow-up. The KM width in the APF plus FGG group (3.85 +/- 1.22 mm) was greater than that in the APF alone (3.05 +/- 0.90 mm) (P = 0.016) and APF plus CM (3.21 +/- 1.17 mm) groups (P = 0.038) at 5 years postsurgery. There was no significant difference in the effective/ineffective outcomes at the 1-year or 5-year follow-up among the three groups. Conclusions: Comparable effective outcomes were achieved with three KM augmentation techniques following the decision-making criterion based on risk assessment.