The prolonged bisphosphonate (BP) uptakes are frequently resulted in BP-related osteonecrosis of jaws (BRONJ). The previous study reported that the BP-involved bones were stained blue by Masson trichrome and showed weak birefringence compared to the normal bone1). Using the representative twenty cases of BRONJ osteomyelitis the present study examined the ultrastructure of BP-involved bone by scanning electron microscope (SEM) using decalcified bone microsections. As the BP-involved bones showed different features from adjacent normal bone by blue staining in Masson trichrome method and by rare birefringence under polarizing microscope, the ultrastructure of BP-involved bone matrixes were distinguishable histologically in comparison with normal bone. The normal bone showed the tight attachment of interdigitating dendritic bone matrixes, producing many Haversian canaliculi, while the BP-involved bone showed the compact alignment of granular bone matrixes, resulted in the abortive Haversian canaliculi. The osteocytes in the lacunar spaces of BP-involved bone became shrunken and necrotic, and the BP-involved bone showed many tunnel-like spaces produced by direct chemical resorptions and proteolytic degradation of bone matrixes. Taken together, it was conspicuous that the BP-involved bones were abnormal in their stainability of Masson trichrome, birefringence under polarizing microscope, and ultrastructure under SEM. These findings of BP-involved bone may have an implication for the pathogenetic roles of BRONJ, and can be applicable for the differential diagnosis of BRONJ from other osseous lesions.

Ⅰ. Introduction
 Ⅱ. Materials and methods
 Ⅲ. Results
 Ⅳ. Discussion
 Ⅴ. References

• 이석근(Department of Oral Pathology, College of Dentistry, Gangneung-Wonju National University) | Suk Keun Lee