The ossicles are often destroyed in patients with chronic otitis media. After removal of inflammatory tissue the surgeon may be confronted with the need to reconstruct the ossicular chain. Apart from homologous ossicles, implants of different materials have been used for this purpose but often without finding the best solution for the problem encountered. As such, we implanted pieces of human dentin and enamel into the middle ears and mandibles of guinea pigs. After staged placements of the grafts in the animal hosts, specimens were removed and prepared for morphological evaluation by embedding in acrylic without prior decalcification. In a mobile unloaded position within the middle ears, implanted specimens were covered by mucosa and showed no evidence for fibrosis or fixation. A joint-like connection to the bony capsule of the middle ear develops as necessary for a type III tympanoplasty. In a mobile, loaded site with contact to bone, implants were surrounded by connective tissue. In connection with the mucosal envelope, this finding confirms the suitability of the materials for ossiculoplasty. When stable within the mandible, implants were surrounded by new bone formation that originated from the host's tissue only, indicating a favorable result for the obliteration of a mastoid cavity. On the surface of both biomaterials, a cell-mediated resorption could be detected, which was more significant in the mandibular site than in the middle ear. However, the long-term biostability of dentin and enamel seems questionable. The synthetic material hydroxyapatite proved less susceptible to biodegradation when tested under identical conditions in a previous experiment.(ABSTRACT TRUNCATED AT 250 WORDS)