Effect of thermocycling on the flexural strength of two different composite filling materials: An in vitro study

Flexural strength is the bend strength or stress which causes failure in bending of the material. Composite is the widely used restorative material in the era of esthetic dentistry as it provides better esthetic and mechanical support for both posterior and anterior teeth. The term "thermocycling" refers to the process of changing temperatures in the mouth. Thus, the aim of the study was to determine the effect of thermocycling on flexural strength in two different composite filling materials. Twelve samples of packable type composite filling material, among which four samples prepared were from Restofill l (Group 1) and four were prepared from Ivoclar Vivadent (Group 2) for the study. Bar-shaped composite resin specimens were prepared with dimensions of 2 mm × 2 mm × 25 mm. Then, the eight samples were subjected to a thermocycling process and four left as control. This was followed by the determination of maximum force by a universal testing machine, and then, the collected data were used to determine flexural strength using the formula. The determining flexural strength was analyzed using SPSS version 23.0 by Independent sample t-test. The mean flexural strength of thermocycled Restofill composite filling material is 6.73, whereas the nonthermocycled Restofill sample showed 5.58 and the mean flexural strength of thermocycled Ivoclar Vivadent composite filling material was 5.08. The difference was not statistically significant with P = 0.978 >0.05. The current study concludes that the flexural strength of the Restofill composite (Group 1) was higher than the Ivoclar composite (Group 2). Hence, thermocycling affects the flexural strength of composite resin.