Retentive Strength of Metal Copings on Abutments using Castor-Oil Polyurethane

Objective: The aim of this study was to evaluate the retentive strength of metal copings on implant abutments after cementation with three commonly used luting agents and an experimental dental luting agent (Castor Oil Polyurethane-COP) with or without different quantities of calcium carbonate (CaCO₃). 

Method: Seventy-two titanium abutments were attached to an implant analog with 35Ncm torque. Wax pattern of copings with a loop in the occlusal surface were made on the abutments. The patterns were invested in a phosphate-bound investment and casted with palladium-silver alloy. Dental luting agents used in this experiment were: G1-provisional cement Temp Bond; G2-Zinc Phosphate cement; G3-resin cement Rely X^TM ARC; G4-pure COP; G5-COP + 10% CaCO₃ filler; G6-COP + 50% CaCO₃ filler. After cementation, the specimens were stored in 37ºC distilled water for 24h. They were submitted to tensile strength test in a universal testing machine (EMIC DL 2000, 5 KN, 0.5 mm/min). Statistical analysis was performed with Kruskal-Wallis and Student-Newman-Keuls test (α=0.05). 

Result: The median values of the retentive strength (N) were: G1=57,20; G2=343,56; G3=40,07; G4=258,98; G5=466,57; G6=209,63. The Kruskal-Wallis test showed statistical differences among the groups (p<0.01). Groups 1 and 3 had the lowest strength; Groups 4, 5 and 6 were equal to Group 2, and Group 5 had the higher strength. 

Conclusion: The retentive strength of metal copings cemented with Castor-Oil Polyurethane is similar to those cemented with Zinc Phosphate, and can be influenced by the addition of calcium carbonate.