Clinical and microbiological evaluation of ligature-induced peri-implantitis and periodontitis in dogs.

The purpose of this study was to evaluate the attachment loss around teeth and implants by clinical and microbiological analysis. The mandibular premolars were extracted in 5 mongrel dogs and, 3 months later, two titanium implants were installed on each side of the mandible and, after another 3 months, abutment connection was performed. Plaque control in the implants and maxillary premolars was maintained for two weeks prior to the start of the main experiment. On day 0 and 30 days after ligature placement, microbiological samples were obtained and relative attachment level was measured for the teeth and implants. The presence of Porphyromonas gingivalis, Bacteroides forsythus, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Prevotella nigrescens was evaluated by polymerase chain reaction technique on day 0 and 30 days after ligature placement. None of the above bacteria were detected on day 0. Thirty days after ligature placement, P. gingivalis was present in 95% and 85% and B. forsythus was present in 80% and 85% of the implants and teeth sites, respectively. Statistical analysis (one-way RM-ANOVA) showed a significant difference (P<0.01) between pre- and post-induction measurements around teeth and implants. However, there was no significant difference (P=0.41) in the rate of attachment loss, between periodontitis and peri-implantitis. It can be concluded that: (1) P. gingivalis and B. forsythus were strongly associated with induced peri-implantitis and periodontitis, and (2) induced peri-implantitis and periodontitis presented a similar rate of attachment loss.