Composite prosthetic components on dental implants: elements arrangement and biomechanics

Abstract

Background: Conventionally, inert and rigid metal, zirconia or ceramic prosthetic components are widely used for dental implant restorations. Connecting a rigid prosthetic element with osseointegrated implant, leads to firm though immobile restoration which is in controversy to physiological mobility of natural teeth. The immobility of dental implant constructions may determine cracks of the prosthesis, peri-implant marginal bone loss, and difficulty to combine natural teeth and dental implants in multiple restorations. Therefore amortization effect of dental implant prosthetic constructions matters of particular importance. Aim: (1) To evaluate the amortization effect and mechanical strength of composite prosthetic dental implant components. (2) To establish the most appropriate dental implant prosthetic construction closest to the mobility and strength of natural tooth. Methods: Ten implants were inserted in acrylic cylindrical blocks. Four groups of prosthetic components were prepared: mono-block composite restoration; composite abutment + ceramic crown; ceramic abutment + composite crown; mono-block ceramic restoration. The crowns were fabricated according to the model of lower second premolar tooth. Prostheses were bonded together and attached to implant titanium connection bases with adhesive systems and dual-curing resin cement. Horizontal mobility of all constructions was tested with electromechanical perio-measuring device. Tension and compression resistance as well as vertical shortening of prosthetic constructions were tested with load measuring device. Data were analyzed statistically using SPSS 19.0 software. Results: Composite mono-block was the most mobile construction horizontally. The mobility of other groups decreased as follows: composite abutment + ceramic crown; ceramic crown + composite abutment; ceramic mono-block. The highest resistance to compression was detected in ceramic monoblocks group. The group of composite abutments + ceramic crowns showed slightly lower mechanical strength, whereas other groups were dramatically lower. Composite abutments + ceramic crowns were shortened at most. The shortening of other constructions decreased as follows: ceramic mono-blocks; composite mono-blocks; ceramic abutments + composite crowns. The analysis of broken restorations after mechanical testing have shown that the adhesion between titanium and cement have been lost in all groups. The adhesion between composite and ceramic was lost only in the group of ceramic abutments + composite crowns. Fragments in the group of composite abutments + ceramic crowns were without any signs of lost adhesion. Conclusions and clinical implications: (1) The utilization of prosthetic composite elements creates amortization effect on dental implants. (2) According to created amortization effect and adequate mechanical strength, combination of composite abutment and ceramic crown seems to reproduce natural tooth largely.