Effect of resin thickness and light-curing distance on the diametral tensile strength of short fibre-reinforced resin composite

This study analyzed the effect of short fibre-reinforced resin composite (SFRC) thickness and light-curing distance on diametral tensile strength. A total of 40 disk-shaped SFRC specimens 3 and 4 mm thick and 6 mm in diameter (n = 20) were divided into two different light-curing distance groups of 2 and 4 mm (n = 10), respectively. All specimens were polymerized using a light-emitting diode (LED) curing unit at irradiance 800 mW/cm² for 20 s. Specimens were tested using a universal testing machine to determine the diametral tensile strength. Diametral tensile strengths were 43.04 ± 1.53 and 41.77 ± 1.79 MPa in the 3-mm thickness groups with 2- and 4-mm light-curing distances, respectively, compared with 42.30 ± 1.77 and 39.46 ± 1.90 MPa, respectively, in the 4-mm thickness groups. There was a significant difference in diametral tensile strength in the 4-mm thickness group with a 4-mm light-curing distance using one-way analysis of variance (ANOVA) and post-hoc Fisher's least significant difference (LSD) tests. It is concluded that SFRC thickness and light-curing distance have an effect on diametral tensile strength.