We implanted keratin and poly(methyl methacrylate) (PMMA) particles to the surface of mouse calvariae to produce a quantitative, localized, inflammatory bone remodeling similar to that seen in cholesteatoma. Both types of particles resulted in increased osteoclast density compared with controls. Osteoclasts infiltrated from marrow and vascular spaces and were active at the periphery of these spaces leading to significant bone remodeling, as demonstrated by the incorporation of bone-labelling fluorophores. Osteoclasts were rarely found on the surface of the calvariae, and mineral apposition rate at the ventral surface was not altered in keratin-implanted animals compared with nonoperated controls. While not useful for the study of the root cause of cholesteatoma, this model will allow the study ofpathologic bone remodeling related to cholesteatoma in a genetically defined animal.