A Strain Gauge Analysis Comparing External and Internal Implant-Abutment Connections

Abstract

This study compared the load transfer characteristics of a complete-arch restoration supported by 4 implants, with external and internal implant-abutment connections. Three loading positions were applied to the prostheses. Epoxy resin models were used to simulate bone. Two types of implants (ReplaceSelect Internal-Interface Tapered Implants and ReplaceSelect External-Interface Tapered Implants) were placed in the models. Complete-arch metal frameworks were constructed on the abutments. Artificial teeth were arranged on the framework, and the prosthesis was screwed onto the abutments. The strain gauges were bonded at the implant-abutment connection level of the specimens with 3 loading conditions (a) 4-point load, (b) 2-point anterior load, and (c) 2-point lateral load. The reading of strain values were recorded and compared. In all load conditions, there were strain differences between the external implant-abutment connection and internal implant-abutment connection. The internal implant-abutment connection resulted in lower stresses at the connection level. When loaded vertically, the internal implant-abutment connection produced less strain when compared with the external implant-abutment connection.