Proliferative activity in peripheral ossifying fibroma and ossifying fibroma.

A proliferative activity study analysing morphometric and quantitative aspects of nucleolar organizer regions (NORs) and proliferating cell nuclear antigen (PCNA) expression was conducted in 10 cases of peripheral ossifying fibroma (POF) and 10 cases of ossifying fibroma (OF). For NOR identification, the silver staining technique (AgNOR technique) was used. PCNA expression was determined by immunohistochemical staining using the PC10 antibody. The AgNOR analysis for the two lesions showed a profile characteristic of benign lesions. OF showed higher AgNOR number and PCNA expression than POF. Our results suggest increased proliferative activity in OF compared with POF.