Polymerization stress is one of the major drawbacks of dental composites and new formulations have been developed to overcome such problem. However, there is a lack of information about the degradation resistance of such materials. The aim of this study was to determinate degradation resistance of materials formulated with silorane, ormocer, dimmer-acid and dimethacrylates.
Method:
Silorane-based, Filtek P90 (P90), ormocer-based, Ceram-X (CX), dimmer-acid-based, N’Durance (ND) and dimetacrilate-based materials, Filtek P60 (P60) and Tetric Ceram (TC), were analyzed. Knoop hardness (KH) was determined before and after 24h immersion in pure ethanol. Flexural-strength (FS) was determined by three-point bending method after one-week storage in dry environment or one-week immersion in pure-ethanol. Data was analyzed by two-way ANOVA and Tukey’s test. The percentages of KH and FS changes after accelerated aging were also considered, and one-way ANOVA followed by Tukey’s test was applied.
Result:
All resin showed reduced KHN after ethanol immersion. P60 presented the highest KHN values before and after ethanol bath; and the lowest percentage of KH decrease (19±5%). TC(48±3%) and P90(39±9%) demonstrated the most pronounced KHN decrease after ethanol storage. FS after one-week storage in pure ethanol affect significantly CX, ND and TC, but not P90 and P60.
Conclusion:
Degradation resistance is determinate by the whole composition and not only by the resin matrix formulation. The new formulations did not improve the degradation resistance when compared to the traditional methacrylate-based materials.