Impact of Keratinized Mucosa Width and Mucosal Thickness on Implant Outcomes and Brushing Discomfort: A 25-Year Cohort Study.

OBJECTIVE: To assess the impact of keratinized mucosa width (KMW) and mucosal thickness (MT) on peri-implant conditions over 25 years in patients with adequate oral hygiene enrolled in regular supportive peri-implant care. METHODS: Partially edentulous patients rehabilitated with tissue-level implants were clinically and radiographically evaluated by calibrated examiners. Patient-reported brushing discomfort was recorded, and associations with variables of interest were analysed. RESULTS: A total of 149 patients, 235 implants, with a mean follow-up of 25.4 ± 3 years, were included. Peri-implantitis prevalence was 11.1%, 0% and 7.1% in the 0-mm, < 2-mm and ≥ 2-mm KMW groups, respectively (p = 0.98). Sites with 0 mm KMW showed significantly greater crestal bone loss (CBL) than < 2 mm (-0.28 mm) and ≥ 2 mm (-0.40 mm) (p = 0.01). Absence of KMW was associated with an increased risk of peri-implant soft-tissue dehiscence (PSTD) and implant platform visibility (p ≤ 0.01). No significant differences were observed for probing depth (PD), bleeding on probing (BOP), plaque index or peri-implant diseases (p > 0.05). MT was not associated with CBL, PD, BOP, suppuration on probing (SOP) or peri-implant diseases (p > 0.05). Thin MT (< 2 mm) was linked to increased PSTD (p = 0.005), greater implant platform visibility (p = 0.04) and lower plaque index (p = 0.01). Brushing discomfort was reported in 11.4% of sites with 0 mm KMW, compared with 3.4% and 2.4% in the < 2 mm and ≥ 2 mm groups, respectively, with no significant associations across KMW or MT groups (p > 0.05). CONCLUSIONS: KMW was associated with long-term peri-implant tissue stability, whereas thin MT was primarily associated with an increased risk of PSTD. Neither KMW nor MT was significantly associated with long-term brushing discomfort.