A comparative crown retention tests using XeraCem™

A simple and reliable luting agent for final cementation is a last critical step towards long-term success when cementing indirect restorations. Objectives: To test an experimental self-sealing acid-base reaction cement (XeraCem™) in vitro for retention. Materials and Methods: Freshly extracted human bicuspids were positioned in the center of Teflon cylinders and imbedded in self-curing resin, leaving the crown extruded. On a jeweler's lathe operating at 1000 rpm the teeth were machined with a diamond disc at low speed (250 rpm) under copious water-cooling. The total angle of convergence measured 32 + 1 degree; the occlusal table ±4 mm. Copings were waxed and cast in type III gold using routine laboratory techniques. 11 copings per group were cemented with: Group 1. XeraCem™, Group 2. MaxCem, Group 3. Ketac Cem, Group 4 zinc phosphate cement and Group 5. UniCem. The samples were stored in water at 370 C for 24 hours before the copings were subjected to a tensile force in an Instron machine. The force at rupture was recorded in Kg/Force. Results: The average force at rupture and standard deviations were: Group 1. 38.6 + 8.5; Group 2. 15.9 + 9.3; Group 3. 26.6 + 4.4 and Group 4. 13.9 +4.5, Group 5. 39.8 + 15.3. An ANOVA demonstrated a significant difference of Groups 1 and 5 compared to Groups 2, 3 and 4 (p<0.01) There was no statistical significant difference between Groups 1 and 5. Conclusion: XeraCem™ demonstrated retentive values usually associated with resin ionomer cements and was much higher than conventional cements with a long track record of clinical success. (This study was supported in part by Doxa Dental AB)