Flexural Strength and Hardness of Short-Silk Fiber-Reinforced Composite with Silane Addition

Aim: To investigate the optimum concentration of silane added in fiber-reinforced composites (FRCs) and its effect on flexural strength and surface hardness. Methods and Material: The degumming process was conducted by soaking the chopped Bombyx mori silkworm cocoons in Na2CO3 solution, hydrolyzing them with NaOH, and neutralizing them with hydrochloric acid. Then, lyophilization and ultra-sonification were carried out. Bombyx mori short-silk fibers (±1.49 µm) were placed into a silane solution with concentrations of 0, 0.5, 1, and 1.5. After silanation, fibers were mixed in a composite resin matrix. The volume fraction of the fiber used was 10. Flexural strength and surface hardness tests employed 48 samples in beam and disc shapes, respectively. Each group included six samples. Flexural strength was tested using a universal testing machine and surface hardness using a microhardness tester in accordance with ISO 4049 (2000). Data obtained were analyzed statistically by analysis of variance (ANOVA), followed by a post hoc least significant difference test. Results: In the ANOVA test, a significant difference was found in the flexural strength and surface hardness among the four FRC groups (P < 0.05). In the post hoc test, the flexural strength of the FRC group with 0.5 silane was significantly different from other groups (P < 0.05). Meanwhile, the surface hardness of samples added with 0.5 silane was not significantly different from those added with 1 and 1.5 silane (P < 0.05). Conclusions: Thus, 0.5 silane might be the optimal concentration to obtain FRCs with appropriate flexural strength and surface hardness. © 2023 Journal of International Oral Health.