Immunolocalization of proliferating cell nuclear antigen in the peri-implant epithelium

The aim of the present study was to investigate the proliferating activity of peri-implant epithelium immunohistochemically using proliferating cell nuclear antigen (PCNA). Eight ITI (Internationale Team für Implantologie) implants were placed into simulated sockets in the mandibles of two beagle dogs two months following tooth extraction. As a control, junctional epithelium of the molar teeth in the same animals were used. The nature of staining and the distribution of PCNA immunoreactivity were determined by scoring a minimum of 100 cells on two sections from each of the implants. In the junctional epithelium, the immunoreactivity to PCNA was detected mainly in the basal cells, in some of the prickle cells, and in a few cells attached to the enamel. In peri-implant epithelium, only some of the basal cells were positive for PCNA. The PCNA score of the peri-implant epithelium was significantly lower than that of junctional epithelium. These results suggest that the peri-implant epithelium maintains a lower capacity to act as a proliferative defence mechanism than does the junctional epithelium.