抄録
Osseointegrated implants have been clinically applied in prosthetic treatments, and many studies have been advocated to investigate them. Among the results obtained from these studies, post operative failures such as abutment fracture have been mentioned. We carried out a prospective study of two-step titanium and hydroxyapatite coated osseointegrated dental implants (provided by KYOCERA) that were clinically used from March 1989 to March 1992, in order to evaluate their long term prognosis. From our evaluation, we also found some clinical cases in which fractures of the abutment screw had occurred around 7 years after implant placement. Possible reasons for these failures are changes in the occlusal pattern, metal fatigue, etc. However, these can be considered causative factors only when they are examined together but not when presented as single factors. We therefore carried out a comparative examination among those abutments having fractures, those without fracture but which were used during the same period of time, and the screw portion of abutments that have not been used yet.
