Objective: To design series of tests to evaluate the retention of crowns to the various types of abutments utilizing different cements.
The tests simulated the clinical retention instead of the routinely measuring indirect physical parameters like Shear Bond Strength, compressive strength, etc.
Methods: 4 types of abutments, precisely prepared special die cut crowns and 6 different commercially available resin based cements, comprising permanent, short and long term temporary cements were evaluated in this study.
Abutments were mounted in the stainless steel cylinders. Tested cement was syringed into each crown after which the crown was firmly seated and either holds in place until final polymerization occurred. The specimens were stored in distilled water at 37 oC for 24 hours prior to testing. Bond strength was measured in accordance with ISO/TS11405:2003 utilizing Lloyd material testing machine equipped with a load cell of 10N and specially designed testing device as a tensile test apparatus. The experimental results were statistically analyzed (N=10) by ANOVA (p<0.05).
Results: Significant differences in bond strength were found between the tested cements groups. Short- term temporary cements exhibited the lowest bond strength, which is critical in order to guarantee their retrievability.
Conclusions: The designed tests simulated the clinical retention and correlate with the findings previously reported by the group. The retention of crowns to the various types of abutments utilizing different cements was defined as a tensile bond strength.