CLINICAL AND HISTOLOGICAL-EVALUATION OF LIGATURE-INDUCED PERIODONTAL BREAKDOWN IN DOMESTIC FERRETS IMMUNOSUPPRESSED BY CYCLOSPORINE-A

The aim of this study was to evaluate, clinically and histologically, the effect of Cyclosporin-A (CyA) on the progression of the periodonta l breakdown in the domestic ferret, using the ligature induced periodo ntitis model. At the start of the experiment (day 0), silk ligatures w ere placed at the gingival margin level of experimental teeth. The con tralateral teeth served as non-ligated control teeth. Clinical measure ments included gingival index, probing pocket depth (PPD), probing att achment level (PAL) and gingival overgrowth (GO) and they were perform ed on days 0, 14 and 28. Cyclosporin-A, 10 mg/kg/d, was given subcutan eously from day 0 to 21, while in the last week there was a reduction of this dose to 5 mg/kg/d. Blood samples were taken on days 0, 14 and 28. On day 28 the animals were sacrificed. Histological sections were prepared for ligth microscopy. The histometric measurements performed were: (1) the distance between cementoenamel junction and the alveolar bone crest and (2) loss of connective tissue attachment. The number o f sections with root resorption areas was observed. Cell counts were t aken in 4 different areas. The results showed, on days 14 and 28, a si gnificant increase of the mean values of PPD and PAL at experimental t eeth as compared to the control teeth. GO was present on experimental teeth on days 14 and 28. On day 28, the control teeth presented a very small increase in GO, mainly at the buccal sites of P4 and M1. The hi stometric results showed a significant loss of attachment and bone res orption in the experimental teeth. Root resorption was found in experi mental teeth only. The predominant inflammatory cell in the 4 experime ntal areas was polymorphonuclears. The number of plasma cells and lymp hocytes was also significantly higher in experimental teeth than in co ntrol teeth. The results indicate that the T-cell immunosystem may par ticipate in defensive mechanisms against periodontal pathology in the domestic ferret, GO may be induced in ferrets under treatment with CyA and this result may be obtained quickly in sites where ligatures have been placed.