Patient- and implant-level factors associated with peri-implant diseases: a retrospective clinical and radiographic study of 968 implants

BACKGROUND: Peri-implant diseases are among the most clinically significant biological complications of implant therapy, yet the relative contribution of patient- and implant-related factors to their development remains incompletely understood. This retrospective study examined the associations between demographic, clinical, and implant-related variables and peri-implant disease status in a large clinical cohort. METHODS: A total of 199 patients with 968 dental implants placed between January 2015 and January 2023 were evaluated. Variables recorded included demographic characteristics, systemic conditions, smoking status, oral hygiene habits, implant-related parameters, clinical indices (plaque index, gingival index, probing depth, attached gingiva width, and gingival thickness), and radiographic marginal bone loss. Peri-implant disease status - classified as peri-implant health, peri-implant mucositis, or peri-implantitis according to the 2017 World Workshop criteria - was the primary outcome. Multivariable generalized estimating equations (GEE) models were applied to account for the clustering of multiple implants per patient. RESULTS: Of the 968 implants, 713 (73.6%) were classified as peri-implant health, 173 (17.9%) as peri-implant mucositis, and 82 (8.5%) as peri-implantitis. In multivariable GEE analysis, smoking ≥ 10 cigarettes/day (OR = 2.55, 95% CI: 1.07-6.10 for mucositis; OR = 4.40, 95% CI: 1.60-12.08 for peri-implantitis), inadequate tooth brushing (OR = 4.65, 95% CI: 1.99-10.86; OR = 5.90, 95% CI: 2.21-15.77), and thin gingival phenotype (OR = 4.22, 95% CI: 2.09-8.51; OR = 15.64, 95% CI: 6.08-40.23) were independently associated with both conditions. Longer implant functional duration was additionally associated with peri-implantitis (OR = 1.57, 95% CI: 1.30-1.90; p < 0.001). CONCLUSION: Within the limitations of this retrospective study, smoking, inadequate oral hygiene, thin gingival phenotype, and longer implant functional duration were independently associated with peri-implant diseases. These findings suggest that peri-implant soft tissue assessment and patient-level risk assessment should be integral components of long-term implant maintenance protocols.