In vitro evaluation of marginal and internal gaps of materials used for onlay and occlusal veneer restorations.

PURPOSE: This study compares the marginal and internal gaps for four restorative materials produced by two fabrication methods in both minimally invasive occlusal veneer and conventional onlay cavities.

METHODS

Eighty mandibular molars prepared as occlusal veneer and mesial-occlusal-distal-lingual onlays and restorations were produced using lithium disilicate glass ceramic, hybrid ceramic, nanohybrid composite, and laboratory composite materials. A silicone replica method was used to examine the marginal gap and internal gap with a stereomicroscope. Two-way analysis of variance (ANOVA) was used to analyze the effects of the material and design, and one-way ANOVA was used to analyze the effect of the fabrication method.

RESULTS

The marginal gap significantly differed in relation to the material, and the internal gap significantly differed in relation to the material and design. Gaps were significantly smaller for the laboratory composite groups than for the other groups. Comparison of fabrication methods showed that internal and marginal gaps were significantly smaller for the conventional procedure.

CONCLUSION

The less complicated designs yielded a better fit. In particular, because of the greater number of intaglio surfaces, internal gap values were worse when cavity design complexity increased.