Abstract
Objectives:The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments.Material and Methods:For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130°C); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5% was adopted for all analyses.Results:The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 μm for any of the experimental conditions.Conclusion:The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values.
Highlights
The great demand of patients for tooth-colored restorations or metal-free restorations and the improvements in the physical properties of composite resins have increased the indications of these materials for esthetic restorations
The composite resin is first lightcured directly in the inlay cavity and the inlay is removed from the cavity and post-cured
For the Vickers hardness test, two 2-mm-thick composite resin increments were inserted into a conical brass mold (3 and 4 mm diameter and 4 mm high), each one being lightcured for 40 s with a halogen light-curing unit (Optilux 501; Demetron/Kerr, Danbury, CT, USA, output 490 mw/cm2)
Summary
The great demand of patients for tooth-colored restorations or metal-free restorations and the improvements in the physical properties of composite resins have increased the indications of these materials for esthetic restorations. Indirect composite resin inlay and onlay restorations are extensively used in esthetic treatments as a less expensive and less technique-sensitive alternative to ceramic crowns[3]. The direct composite resin inlay/onlay technique was introduced to improve the adaptation in Class II cavities[1], being less expensive than indirect ones and built up clinically. In this technique, the composite resin is first lightcured directly in the inlay cavity and the inlay is removed from the cavity and post-cured. Peutzfeldt and Asmussen[17] (1991) did not find these results for all composite resins evaluated in their study
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