The lack of keratinized mucosa as a risk factor for peri-implantitis: a systematic review and meta-analysis

This study aimed to investigate the effect of the lack of keratinized mucosa on the risk of peri-implantitis, while also accounting for possible confounding factors. A literature search was conducted in PubMed and Scopus, including human studies that assessed the presence and width of keratinized mucosa in relation to the occurrence of peri-implantitis. Twenty-two articles were included, and 16 cross-sectional studies we meta-analyzed. The prevalence of peri-implantitis was 6.68-62.3% on patient-level and 4.5-58.1% on implant-level. The overall analysis indicated that the lack of keratinized mucosa was associated with a higher prevalence of peri-implantitis (OR = 2.78, 95% CI 2.07-3.74, p < 0.00001). Similar results were shown when subgroup analyses were performed, including studies with a similar case definition of peri-implantitis (Marginal Bone Loss, MBL ≥ 2 mm) (OR = 1.96, 95% CI 1.41-2.73, p < 0.0001), fixed prostheses only (OR = 2.82, 95% CI 1.85-4.28, p < 0.00001), patients under regular implant maintenance (OR = 2.08, 95% CI 1.41-3.08, p = 0.0002), and studies adjusting for other variables (OR = 3.68, 95% CI 2.32-5.82, p = 0.007). Thus, the lack of keratinized mucosa is a risk factor that increases the prevalence of peri-implantitis and should be accounted for when placing dental implants.