Histomorphometric analysis of osteoclastic resorption in bone directly invaded by gingival squamous cell carcinoma

Whole frontal sections of the mandibular bone from 18 patients with gingival squamous cell carcinoma showing direct bone invasion were prepared for histometrical analysis by a non-decalcified grinding method. The osteoclast cytoplasmic area in tumor sites was larger and its relative frequency distribution was broader than that of osteoclasts in non-tumor sites. The index of bone resorption was significantly increased, while that of bone formation was decreased, in the tumor sites compared to the non-tumor sites (P < 0.01). In the tumor sites, the indices of bone resorption and formation in the group showing greatest chemotherapy and radiation therapy effects (CRE) were significantly different from those in the group with low CRE (P < 0.01). A history of irradiation therapy was associated with significantly decreased bone resorption (P < 0.05).