Objectives: The popularity of the "Open Sandwich" technique is due to its' clinical success and relative ease. However, clinical studies have demonstrated a low precentage of failures resulting from "delamination" of the microhybrid composite occlusal component from the resin modified glass ionomer base component. The failures clinically appear to originate at the marginal ridge of the restorations due to flexing at the composite RMGI interface. This study measured the flexural strength and modulus at the interface of eight different restoration groups. Methods: Ten cylinders each of eight different sets, approximately 2mms by 12 mms, were prepared: Group A; AeliteLS (Bisco)/PhotacFil(3M/Espe) without adhesive, Group B;StarFlow (Danville) /Bisco RMGI without adhesive, Group C; AeliteLS/Bisco RMGI without adhesive, Group D; AeliteLS/ PhotacFil with DE Bond (Bisco), Group E; AeliteLS/FujiII LC (GC America) with DE Bond, Group F; AeliteLS/FujiII LC with OneStep (Bisco) adhesive, Group G; AeliteLS PhotacFil with One Step adhesive and Group H; UniFil Flow/FujiII LC with UniFil Bond adhesive (GC America). Each sample was hydrated in de-ionized water for 24 hours before testing. Exact measurements of each sample were obtained before testing with a universal "Q"TESTER (MTS). Results: Group C had significantly higher flexural strength ( ANOVA analysis Df 7 P=0.000)than the other groups. Otherwise,the addition of an adhesive improved the interfacial bond. Microscopic examination of the fractured samples revealed that voids contributed to the fracture of certain groups (non adhesive) of samples. Conclusion: The failure at the interface is related to incompatible materials or inappropiate technique in use for adhering composite to the RMGI base, resulting in delamination of "Open Sandwich" restorations.

Back to the Dental Materials: I - Adhesion-Composite Bond Strength Program
Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

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