Assessment of laminate technique using glass ionomer and resin composite for restoration of root filled teeth

摘要

Objective: To evaluate the open laminate technique using glass ionomer cements (GIC) in association with a low shrink composite for restoring root filled premolars. Methods: Extensive MOD cavities plus endodontic access and root filling were performed in intact extracted maxillary premolars. Three restoration types were evaluated: (1) resin composite alone; (2) resin-modified GIC (RM-GIC) open laminate plus resin composite; (3) conventional GIC open laminate plus resin composite (n = 8 for all groups and tests). Three tests were conducted to assess restorations: (A) inward cusp deflection during light curing, using DCDTs; (B) fracture strength using a ramped oblique load at 45°to the long axis in a servohydraulic testing machine in comparison with intact and unrestored teeth; (C) proximal marginal leakage using methylene blue dye and the effect of thermocycling. Data were analysed using 1-way ANOVA for cuspal deflection and fracture strength and Fisher's exact test for leakage. Results: Laminate restorations resulted in significantly less cuspal deflection compared with resin composite (4.2 ± 1.2 μm for RM-GIC and 5.1 ± 2.3 μm for conventional GIC vs. 12.2 ± 2.6 μm for composite, P < 0.001). Fracture strength was not significantly different among all groups. Failure with all restorations was predominantly adhesive at the tooth-restoration interface. The two laminate groups showed significantly better marginal seal than composite alone, but sealing ability of conventional GIC deteriorated after thermocycling. Conclusions: Laminate restoration of root filled teeth had beneficial effects in terms of reducing cuspal deflection and marginal seal, with acceptable fracture strength.