Ligature-induced marginal inflammation around osseointegrated implants and ankylosed teeth.

The purpose of the investigation was to gain more understanding of marginal inflammatory reactions around osseointegrated implants. The significance of the lacking periodontal ligament of implants was examined in the initial breakdown phase of supporting tissues by comparing clinical and radiographic manifestations of ligature-induced marginal inflammation related to osseointegrated implants with those around ankylosed and normal control teeth in 8 cynomolgus monkeys (Macaca fascicularis). Bilateral extraction of the first and second mandibular molars was carried out initially, and 12 weeks later 2 implants were placed in each side. Ankylosis of the second maxillary molars was established by extracting and replanting the teeth after a drying period. When ankylosis and osseointegration were established, ligature-induced marginal inflammation was induced in the right or left side at random around implants, ankylosed teeth and normal control teeth (second maxillary premolar) for 7 weeks. Although the clinical manifestations as expressed by plaque score, gingival score, probing depth and attachment loss were quite similar, the radiographic features differed. Significant loss of bone height was limited to implants and ankylosed teeth and did not occur in relation to normal control teeth. Furthermore, the bone loss around implants was significantly greater than the loss around ankylosed teeth. Bone loss was limited to implants and ankylosed teeth; the study therefore suggests that the presence of marginal inflammation around implants and ankylosed teeth may have more serious implications than does marginal inflammation around teeth with a periodontal ligament. However, variations in microbiota and susceptibility of different jaw positions to periodontal breakdown may influence the results of this study.