抄録
The objective of this study was to identify clinical issues of dental implant treatment over the long term.
The study included 281 titanium screw implants and 90 superstructures that were placed in 66 patients at a single dental clinic in Japan from 1987 to 1992. The cumulative success rate of the embedded implants over a 20- to 25-year period was obtained by life table analysis. In addition, the rates of problem occurrence in the study patients, implants, and superstructures were calculated.
More than half of the patients (n=39) dropped out of the study during the study period. The cumulative success rate for 25 years for the implants was 85.6%. Regarding the region of implant placement, no significant difference in the cumulative success rate was found between the maxilla and the mandible, whereas, concerning the long axis, the cumulative success rate was significantly lower in the implants having a long axis of 7 mm compared to those with a long axis of 10 mm or longer.
During the observation period, the rates of problem occurrence in the implants were 9.6% and 22.7%, respectively for the implants and the patients. On the other hand, the problem occurrence rates of the superstructures were 54.4% and 74.2%, respectively for the superstructures and the patients, during the observation period.
The long-term cumulative success rate of the machined-surface implants was good, whereas many more clinical problems occurred in the superstructures than in the implants. Therefore, it is important to design and produce superstructures that entail less strain of repair or reproduction over a long-term observation period. Additionally, in dental implant treatment in the future, ingenious ways need to be developed to address various challenges due to aging in patients as well as to encourage regular visits for maintenance treatment.
