Tolerance Test of Five Different Types of Crowns on Single-Tooth Implants

Purpose: The main purpose of the present experimental study was to compare five different types of crowns, cemented on implant abutments, regarding their capability to withstand loads. Materials and Methods: Three types of all-ceramic crowns, a gold-foil-reinforced porcelain crown, and, as a control, a conventional metal ceramic crown were tested. Each crown was cemented onto an Astra Tech Single-Tooth implant. The five types of crowns, three of each type, and the titanium implants were subjected to loading in Lloyd test equipment until part of them was damaged, at which point the compression value was recorded and the deflection and bending moment were calculated. Comparisons were made on the basis of these data. Results: The results showed that the all-ceramic crowns fitted with a core should be able to withstand normally occurring biting forces without difficulty. The foil crown was also judged to be acceptable, while the bending moment of the cast all-ceramic crown without a core was considered unpredictable. The values for the metal ceramic design were as predicted, ie, they were clearly the highest in the study; the superior strength of metal ceramics should still be taken into account when deciding between all-ceramic colutions and the conventional metal ceramic crown. Conclusions: It was concluded that all-ceramic crowns are weak er than conventional metal ceramic crowns; however, based on estimated maximum clinical loadign (370 N in the incisor and premolar regions), In-Ceram and AllCeram crowns seem to function satisfactorily on implants.