HOLLOW IMPLANTS RETRIEVED FOR FRACTURE - A LIGHT AND SCANNING ELECTRON-MICROSCOPE ANALYSIS OF 4 CASES

ONE OF THE POSSIBLE COMPLICATIONS Of implant treatment is the occurren ce of an implant fracture. Metal fatigue and biomechanical overload se em to be the most common causes of fractured implants. This study eval uated 4 implants (3 hollow cylinders and 1 hollow screw) which fractur ed after a mean loading period of 2.8 years. All implants had a 4 mm d iameter and had been inserted in a posterior location. In 3 cases para functional habits were present. In all cases a vertical resorption of the peri-implant bone was present. The endosseous portion of the impla nt presented always a very high bone-implant contact percentage. Scann ing electron microscopic examination showed that at least one of the i mplant holes was involved in the fracture line; no porosities or mater ial defects were observed on the fractured surface of the implant. In hollow implants the holes could represent a site of less resistance.