The aims of this study were as follows: (1) to analyze and compare osteoclasts in terms of the quantity, morphology, and expression of TRAP and DC-STAMP in formalin-fixed routine jaw bone specimens from patients with MRONJ (BP), OM, ORN and normal jaw bone (control); (2) to investigate the status quo of osteoclast activity and cell–cell fusion (mononuclear cells and osteoclasts) in MRONJ (BP) specimens; and (3) to investigate if disease-characteristic osteoclast profiles exist that might facilitate the histopathological differentiation of MRONJ (BP), OM and ORN. This evidence concerns the gene ACP5 and ocular melanoma.