The Laboratory Investigate Of The Fit Of Superstructure Of Implant Denture

Objective The fit of superstructure of implant denture is very important to the success of implant. The implant superstructure with good fit would have good osteointegration and longevity. On the contrary, if the fit between superstructure and denture was not good enough, wrench and pressure would be emerged, and the unfitness would lead to distortion, fracture of denture, micro-fracture, the loss of osteointegration, and eventually the failure of implant. The objective of the study was to investigate the influence of the fit between parts of implant denture in different technology and search for a best way to manufacture metal prosthesis.Materials and Methods Three different technology was used to produce implant metal prosthesis. They were wax casting finished plastic cap casting and computer-controlled electric spark erosion. Then metal prosthesis were made, mounted and bonded tothe abutments, In the vertical and horizontal direction, the composite of prosthesis and abutments were cut and the fit between prosthesis and abutments was examined by SEM. Data were counted and analyzed by spss.Results The fit of metal prosthesis with wax casting method was poor; The mean gap was bigger than the one in the other two ways(p<0.01). There was no considerable difference in mean gap between finished plastic casting cap group and computer-controlled electric spark erosion group(p>0.05). The insertion rate of metal prosthesis with wax casting and finished plastic cap casting is low; while all the metal prosthesis with computer-controlled electric spark erosion method were inserted on the abutments successfully.Conclusions The technology of computer-controlled electric spark erosion was the best way to manufacture metal prosthesis, It represented the irresistible general trend in technology. Wax casting should be eliminated because of its too many influential factors; it could still be a feasible way with high insertion rate and no decline of precision, on condition that we could adjust the gap between finished plastic cap and abutment, but it was still a casting way, so it could not break the limit of casting technology. In fact, the aim was too difficult to realize.