Jaw exostoses associated with osseointegrated dental implants. Report of three cases of a newly described phenomenon

Background: Various irritating factors may cause activation of the periosteum resulting in peripheral bone deposition and exostosis formation. However, dental implant placement has not been associated with development of exostoses. In the present clinical report, three cases of exostoses developing subsequent to dental implant placement are reported and the possible pathogenetic role of periosteal activation is discussed. Case reports: In Case 1, a 51 years old Caucasian woman developed bilateral hard buccal maxillary swellings, about six months after immediate dental implant placement into the extraction sockets, without raising a flap. The swellings remained asymptomatic but showed progressive enlargement during a 5-year follow-up period reaching a maximum diameter of 2 cm. Panoramic radiograph and dental computed tomography showed expansion of the buccal cortical plate and increased bone density. Histopathological examination of the lesion revealed mature compact bone. In Case 2, a 63 years old Caucasian woman presented with an anterior palatal hard tissue swelling; a dental implant had been placed in the left central incisor area two years before, following the same surgical method for implant placement as in Case 1. Case 3 was a 54 years old male with a hard swelling of the buccal side of the mandible in the area of the first and second molar, adjacent to dental implants placed about 2 years before. In this case, the immediate implants were placed after flap elevation. Conclusion: Hard tissue swellings presenting as jaw exostoses in areas of previously placed dental implants are possibly due to periosteal activation caused by the mechanical trauma, mild inflammatory reaction and/or occlusal overload associated with the implant. The exact etiopathogenesis, the frequency and the clinical relevance of periosteal activation and new bone formation in the context of dental implant osseointegration demand further investigation.