Clinical and microbiological effects of localized ligature-induced periodontitis on non-ligated sites in the cynomolgus monkey

The purpose of this study was to examine the clinical and microbiological effects of localized ligature-induced periodontitis on non-ligated sites in a monkey model system. Ligature-induced periodontitis was produced in one quadrant in each of four Macaca fascicularis monkeys. Two additional monkeys without any ligatures served as control. The clinical condition and subgingival microflora of ligated, non-ligated, and control sites were monitored for 8–11 weeks. Ligated sites demonstrated an initial (1–2 weeks post-ligation) increase in inflammation, Gram-negative surface translocating bacteria (STB), and motile rods. Clinical and radiographic evidence of loss of attachment associated with increased proportions of Bacteroides gingivalis was evident 4–6 weeks post-ligation. No clinical changes were demonstrated in non-ligated and control sites throughout the experimental period. Non-ligated sites, however, demonstrated an increase from 4.6% to 13.7% in Gram-negative STB and motile rods by 4–6 weeks which continued to increase to 20.3%, by 8–11 weeks. Control sites showed no microbiological changes during the experimental period. In a second experiment pure cultures of B. gingivalis were implanted subgingivally at various times in non-ligated sites. It was only possible to recover increased proportions of B. gingivalis from non-ligated sites when implantation occurred while proportions of Gram-negative STB and motile rods were elevated. Loss of attachment in infected non-ligated sites was not seen within four weeks of implantation.