MAINTENANCE OF NEW CEMENTUM FORMED DURING CYCLOSPORINE-A ADMINISTRATION AFTER SUSPENSION OF THE TREATMENT

The aim of the present investigation was to examine if new cementum (N C) formed during cyclosporin A (CsA) administration was maintained aft er supension of the treatment. Thirty mg/kg/d of CsA were given to 3 m ale Sprague-Dawley rats. Three control rats received oil-based vehicle solution. Nine wk later the drug and vehicle administration were stop ped and the rats continued to be fed with the same standard laboratory diet and water ad libitum for 5 months. The rats were anaesthetized, the tissues fixed by intracardiac perfusion of fixative solution and t he mandibles processed for Epon inclusion. Histological, histomorphome tric and ultrastructural analysis revealed that (a) NC covered extensi ve areas of the root surfaces; its structural characteristics were ide ntical to those observed in the rats killed during CsA administration. (b) collagen fibres of the adjacent connective tissue were functional ly inserted into the NC. (c) In the presence of cervical NC spurs the extent of the apical downgrowth of the junctional epithelium, measured parallel to the cemento-dentinal junction, was decreased (up to 64%) compared to the one occurring in areas devoid of NC deposits. These re sults suggest that (a) NC deposition and its Functional relations with the adjacent connective tissue are not reversible after cessation of CsA treatment and (b) in the presence of cervical NC spurs the amount of connective tissue attachment on the root surfaces is increased.