Metal ruber-dam retainers may damage tooth structure, restorations, and the porcelain surface of crowns. In this study, effects of metal versus plastic retainers on the surface of porcelain fused to metal (PFM) were compared, specifically: defects at point of beak contact, and porcelain fracturing. Evaluation was performed with scanning electron microscopy (SEM); micrographs were examined for porcelain defects. No damage was evident with metal or plastic retainer placement. In conclusion, neither metal nor plastic retainers consistently damaged PFM surfaces.