Factors affecting peri-implant bone resorption in four Implant supported mandibular full-arch restorations: a 3-year prospective study.

BACKGROUND: Peri-implant marginal bone-level (MBL) alteration represents one of the parameters included in the criteria for determining implant health.

OBJECTIVE: Factors affecting peri-implant MBL alteration for 4-implant-supported fixed mandibular prostheses (4-ISFMP) were assessed.

MATERIAL & METHODS: A 3-year prospective, cohort study was conducted on 44 mandibularly edentulous patients treated with 4-ISFMP. Peri-implant MBL alteration was evaluated radiographically at the 12-, 24- and 36-month follow-ups considering to patient-related risk factors [age, gender, diabetes mellitus, smoking, cardiovascular disease (CVD), rheumatic disorders (RD)] and implant/prosthesis-related features (implant location, keratinized gingiva, denture cantilever length, prosthesis supporting zone, opposing dentition) as well as to peri-implant biological parameters (plaque-, bleeding-, calculus index).

RESULTS: 148/176 implants (37 patients, drop-out: 15%) were followed for 3 years showing significant (p < 0.001) annual differences of MBL alterations over time. The univariate analysis demonstrated differences of MBL alterations for smokers (p = 0.014), for patients with CVD (p = 0.001) and RD (p = 0.011). In the 3-year multivariate analysis, MBL alteration was influenced by time (p < 0.001) and showed relationship with risk factors as smoking (p < 0.002; OR = 18.965), CVD (p < 0.021; OR = 5.172), RD (p < 0.006; OR = 50.171) and plaque-index (p = 0.034; OR = 3.252).

CONCLUSIONS: Although peri-implant MBL alteration increased annually, significant odds ratios, were found for patients-related risk factors identifying them potentiating the alterations.