Development of a peri-implantitis model in the rat.

Objectives: The aim of the present study was to establish a rodent peri-implantitis model induced by a mixed bacterial infection characterized by bone loss and semi-quantitative graduation of peri-implant inflammation in histological sections.
Materials and Methods: Two titanium implants were implanted in Sprague-Dawley rats, bilaterally in each maxilla. After 3 weeks healing, the rats were randomized into three groups according to different treatments over the next 3 months: Antibiotic-Group with oral lavage of antibiotics; Bacteria-Group with oral lavage of Streptococcus oralis and Aggregatibacter actinomycetemcomitans; and Untreated Group with standard housing and no additional treatment. Maxillae were dissected to perform microscopic and histological analysis of bone height and peri-implant tissues.
Results: The bone level, measured at one implant site per animal, in the Bacteria-Group (2.60 ± 0.39 mm) was significantly reduced compared to the Antibiotic-Group (2.29 ± 0.32 mm) after 3 months. The differences of bone height in the Bacteria-Group and the Untreated Group (2.46 ± 0.27 mm) did not reach statistical significance. The inflammatory response with respect to the number of inflammatory cells and fibrous tissue compartments of the peri-implant tissues in the Bacteria-Group was significantly increased compared with the Antibiotic-Group (p < .05). S. oralis and A. actinomycetemcomitans DNAs were detected in the Bacteria-Group.
Conclusions: This rat model of peri-implantitis used oral bacterial lavage for the induction of an inflammatory host response and bone loss. Additional bacterial treatment enhances the peri-implant phenotype, so that significant differences to a reduced bacterial load similar to the human peri-implantitis disease can be identified.
(© 2019 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)