The purpose of this study was to measure axial loading, generating bending moments on fibre reinforced composite (FRC) implant prostheses using strain-gauged customized abutment in vivo. Bending moments of conventional implant prosthetic material were also measured and the data were compared with those for FRC. Three unit fixed dental prostheses were made for two dental implant fixtures, which had been functioning properly for more than one year using Tescera ATL, porcelain fused to metal and gold as occlusal material. Three patients participated in this study; two patients had two implants on one side of the mandible and one had two implants on both sides of the mandible. Five sets of fixed dental prostheses were fabricated for each material and these were cemented with Temp-bond on strain-gauged customized abutments, which were screwed into the underlying implant fixtures. Axial loadings and bending moments were measured when a patient bit the experimental fixed dental prosthesis. ANOVA and the Tukey HSD test (alpha = 0.05) were used for statistical analysis. There were no significant differences in normalized bending moments among the three different implant prosthetic materials. Within the limitations of this study, Tescera ATL generated bending moments similar to conventional implant prosthetic materials such as gold and porcelain.