Fareiborz Vafaee - Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran
Zahra Bagheri - Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran
Saeed Nikanjam - Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran
Fahimeh Daneshyar - Department of Pediatricdentistry, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran

Background: This study compared the amount of residual cement at the margin of implant-supported crowns cemented using the polytetrafluoroethylene (PTFE) tape, replica technique, and conventional cementation technique. Methods: In this in vitro experimental study, a mandibular model underwent full-arch scanning. The right first molar tooth was eliminated on the scan using Exocad software, and a regular implant analog was modelled using the Exocad model creator. The designed abutment was then printed. The implant analog was fixed in place with acrylic resin and scanned using a scan body. A full-zirconia custom abutment was then designed by Exocad. Abutments were fabricated using zirconia and sintered. Twenty-seven resin crowns were fabricated for the abutments, and their fit was assessed. Nine crowns were conventionally cemented by filling half of the crown space with cement, ۹ crowns were cemented using PTFE tape, and the remaining ۹ were first placed on a resin replica and then cemented on the abutments. The residual cement was weighed using a digital scale, and the groups were compared by one-way ANOVA and LSD test (α = ۰.۰۵). Results: The amount of residual cement was significantly different among the three groups, indicating that the amount of residual cement was the highest in conventional cementation, and the lowest in the replica group (P < ۰.۰۵). Pairwise comparisons showed significant differences between all groups (P < ۰.۰۵). Conclusions: The replica technique followed by the PTFE tape resulted in the minimum amount of residual cement at the margin of implant-supported cement-retained crowns and are preferred for use in the clinical setting.

Dental cements, Crowns, Dental prosthesis, Implant-supported, Polytetrafluoroethylene