Effects of occlusal overload on peri-implant tissue health: A systematic review of animal-model studies

Background: This study systematically evaluates the effect of occlusal overload (OV) on peri-implant tissue health in animal studies. Methods: MEDLINE, EMBASE, and LILACS databases were searched for articles published up to and including January 2010. Studies that reported outcomes of non-splinted titanium dental implants submitted to OV were eligible for inclusion. Probing depth (PD), clinical attachment level (CAL), radiographic and histologic distances from the implant base to the most coronal point of bone-to-implant contact (RDIB and DIB, respectively), and bone density (BD) were the main outcomes of interest. Results: Two controlled trials were included in this review and both were considered at a high risk of bias. The marked heterogeneity between studies did not allow data to be combined for meta-analyses. Two studies reported no association between OV and peri-implant tissue breakdown in the absence of dental plaque, with PD and CAL varying from 2 to 3 mm at the end of the experiments. In the presence of plaque accumulation, OV played a key role in peri-implant tissue breakdown (PD change: 5.3 mm; DIB: 6.0 mm). Trends suggested that OV may increase BD. Conclusions: Data on OV on stable implants are limited and conflicting. OV may lead to bone loss in the presence of dental plaque and to an increase in BD in areas where plaque control is performed.