The effect of different curing distances on the microflexural strength of nanohybrid and giomer composite resins

Abstract

Background and Aim: Light activated composite resin is considered as the choice of restorative material due to its high aesthetic demand. Various external and internal factors affect the effectiveness of polymerization, which may affect the life of the final restoration. Our aim was to investigate the effect of different curing distances on the micro flexural strength of nanohybrid composite and giomer.

Materials and Methods: In this study, FiltekTM Z250 XT composite and Beautifil giomer were used. 60 rectangular specimens (6 mm * 2 mm * 1 mm) were prepared (30 samples for each composite type, 10 samples were placed in each sub- group depending on the distance from light source). Samples were light-cured at three different distances (0 mm, 2 mm and 8 mm) according to the manufacturer's instructions for each composite and kept in deionized water at 37 ° C for 24 hours. The micro flexural strength test was performed by a universal test machine at a speed of 1 mm / min. SPSS software version 17 was used for data analysis. A probability value of less than 5% was considered a significant level.

Results: According to the findings of this study, the highest mean flexural strength was related to the light cure group at a distance of 0 mm. According to the results of two-way analysis of variance (Two way ANOVA), there was a significant difference between the mean micro-flexural strength at different distances of the curing (P-Value = 1.925). There was significant difference between the mean flexural strength at a distance of 0 mm and its mean at the other two distances, but there was no significant difference between 2 and 8 mm. Also, there was a statistically significant difference between the mean micro-flexural strength of the two composites and the mean micro-flexural strength of 3M Z250 composite was higher than the Shufo composite.

Conclusion: According to the obtained results, in general, it can be said that by increasing the curing distance, the micro-flexural strength in both resin and giomer based composites decreases and the micro-flexural strength in Z250 composite is higher than Shufo composite.