The purpose of the present study was to look into the effects that various factors related to implant-supported prostheses have on clinical outcomes. A total of 2,291 men and women participated in this retrospective study, and 5,092 implants placed in 2,969 cases were examined.
The survival rate for removable implant-supported prostheses, which can be taken care of easily, and which readily keep peri-implant tissues clean, was 97.7%, while the rate for implant-to-implant connected prostheses, in which biomechanical loading is not applied through the periodontal ligament, was 97.6%. These connection-type and implant-supported prostheses exceeded other types in survival rate. The survival rate for implant superstructures loaded three months and upward after first surgery was significantly high (96.7%). As was found in the cases of screw-type and cylinder-type implant (96.4% and 97.3%), the survival rates for titanium plasma sprayed-and hydroxyapatite-coated implants with surface roughness were also as high as 98.2 and 96.7%. The survival rate of 95.9% for implants of 10 to 15 mm in length was high, compared with the rates for plants longer than 15 mm and shorter than 10 mm. The survival rates for implants 3 mm and 4 mm in diameter were as high as 96.7% and 96.2%, respectively, but the rates dropped sharply for those 5 to 6 mm wide. Implant survival rates reached 95.9% and 96.1% in the regions where bone was satisfactory in both quality and quantity. Where these alveolar bone conditions were insufficient, the rate became low. A combination of implants and GBR (guided bone regeneration) did not contribute to raising the survival rate.
In conclusion, the present retrospective study suggested that, if it is to achieve a good result and a high survival rate, implant treatment should be done with our findings taken into due consideration.