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

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 of varying screw access channel filling methods on the retention of implant-supported prosthesis. To perform this experimental study, forty titanium implant abutments (Biohorizons) were placed in implant analogues. Implant analogues were mounted in acrylic resin blocks using surveyor. After fabrication of crowns for each abutment, 3.5 mm of the flat axial wall of all abutments was removed. Specimens were divided into 4 groups. In three groups, the screw access channels were fully filled with Wax, Polyvinyl Siloxane and Cotosol. In the fourth group, access hole partially filled with wax. Provisional luting agents Temp-Bond, Dycal and Temp-Bond NE were used to secure the crowns to the respective abutments. All specimens were stored in 100% humidity environment prior to testing. Each crown was pulled using a universal testing machine and tensile strength was recorded (N). Data were analyzed using ANOVA. When Dycal was used for cementation, higher tensile strength was observed by partially filled access hole with Wax, fully filled with Wax, Cotosol and Polyvinyl Siloxane respectively. Temp-Bond NE showed significantly higher tensile strength when Polyvinyl Siloxane was used as screw access channel filling material. However, no difference was found in tensile strength of Temp-Bond with different materials used for filling of access hole. The retention of castings cemented to implant abutments with Temp-Bond NE or Dycal is influenced by the filling modality of screw access channel.