HISTOLOGICAL AND MICROBIOLOGICAL ASPECTS OF LIGATURE-INDUCED PERIODONTITIS IN BEAGLE DOGS

This study was designed to investigate, using 6 beagle dogs, the level s of selected putative pathogens in healthy sites, in gingivitis sites , and in sites with histologically confirmed attachment loss. Levels o f attachment loss increased with increasing periods of ligation and re ached a maximum of 0.15 mm at 57 days. Both histological attachment le vel and histological pocket depth were found to vary significantly wit h health/disease status (p<0.0001). Higher numbers of total colony-for ming units were seen for ligated sites than for healthy and gingivitis sites. Levels of Porphyromonas gingivalis and Plevotella intermedia a lso changed significantly with health/disease status (p<0.001). These organisms showed their greatest increases at the time of the most inte nse attachment loss. Higher levels of Fusobacterium necleatum were see n in the gingivitis sites than in healthy or ligated sites. Low levels of Campylobacter rectus and Capnocytophaga spp. were detected through out. The morphometric microbiological analysis revealed unexpectedly h igh %s of motile rods, while spirochetes were found in very low %s. Th e total number of bacterial cells detected using phase contrast micros copy was not found to vary significantly. None of the morphotypes were demonstrated as showing significant changes with health/disease statu s.