Evaluation of Effect of Screw Access Cavity Filling Material and Cement on Retention of Implant Cemented Crowns

Implant-supported prostheses can be screw-type or can be cemented onto the abutment. Use of permanent cements, which are used in conventional prostheses, is not recommended for implant-supported prostheses. These cements are very strong and do not allow easy removal of the prosthesis. By using temporary cements not only permanent cement faults will be eliminated but also prosthesis can be retrieved as needed. The aim of this study was to evaluate the effect of screw access filling material and cement on the retention of implant cemented crowns. In this in vitro study, 5 angulated abutments (15°) were screwed onto the analogue and ten crowns were fabricated for each of them. Four filling materials, Coltosol, composite resin, Teflon tape and silicone, were used to fill the access cavity and one abutment was left empty (only the screw was covered). Two temporary cements (Temp Bond and Temp Bond NE) were used to cement the crowns. The force required to remove the crowns was measured with a universal testing machine at a crosshead speed of 5 mm/min. Data were analyzed with ANOVA and Tukey test (α = 0.05). In all the samples, the force required to separate the casting crowns from the abutment were higher in Temp Bond NE group and this difference was statistically significant (p value = 0.007). In addition, the difference between the access filling material was statistically significant (p value 0.001). Therefore in each group, Coltosol, empty, composite resin, Teflon and the condensational silicone exhibited the highest means of separating force in ascending order. Retention of implant-supported crowns was influenced by types of filling material, access cavity and cement used.