The effect of inadequate access to peri-implant hygiene on marginal bone level. A 4-year cohort prospective study.

OBJECTIVE: The objective of this four-year cohort prospective study was to evaluate the effect of inadequate access to peri-implant hygiene on marginal bone level (MBL). MATERIAL AND METHODS: Forty-one partially edentulous patients (16 males and 25 females, aged 49.8 +/- 11.9 years) who had implants with at least one year in function were selected. Patients were clinically and radiographically evaluated at three different times: baseline (T0), 2-year (T1), and 4-year (T2) follow-up intervals. At baseline, implants were classified and allocated into two groups: those presenting adequate access (ACC) and inadequate access (no-ACC) to peri-implant hygiene. A linear mixed-effects model for clustered longitudinal data was used to analyze MBL, probing depth (PD), plaque index (PI), and bleeding on probing (BoP). RESULTS: Of 131 implants, 74 were considered as having ACC, and 57 as having no-ACC at T0. Implants in the no-ACC group presented a statistically greater mean MBL measurement at T2 than implants in the ACC group (p = .011). In the no-ACC group, a significant reduction in PD from T0 to T1 (p = .019) and from T0 to T2 (p = .010) was observed. Regardless of the group, PI significantly increased at both T1 (p = .00001) and T2 (p = .00004). Regardless of time, the prevalence of BoP was significantly higher in the no-ACC group than in the ACC group (p = .012). CONCLUSION: Inadequate access to peri-implant hygiene frequently resulted in more peri-implant inflammation and MBL over time. Proper accessibility to peri-implant hygiene should be carefully considered during planning of implant restoration, and patients properly motivated into maintenance care.