The effects of abutment screw access channel filling material and its amount on resistance to dislodgement of cement retained implant-supported crowns

Factors affecting the retention of fixed prosthesis to natural abutments are well understood. In contrast, little is known concerning factors influencing the retention of fixed prostheses cemented to implant abutments. The purpose of this study was to investigate the effect that varying screw access channel filling materials and methods has on the retention of casting cemented to implant abutment A 15 degree preangeled abutment (Noble biocare Replace) was placed in implant analogue. Ten crowns were constructed that incorporated an attachment to allow removal. The screw access channels were either fully or partially filled with Gutta perka, Composit or silicone. Crowns were cemented to the abutment with TemoBond. The tensile force required to separate the cemented crowns from the abutment was measured using an Instron universal load testing machine. The mean peak removal force was significantly higher with partially filled access hole compared with fully filled. About the material filling the screw access hole, the mean peak removal force was highest with Composit and that was greater than Gutta perka and silicone respectively. The method and materials selected to fill the screw access channel of an implant abutment can be a significant factor affecting retention of a cemented restoration.