Application of a Glass Fiber-reinforced Composite Material to Clasps: Study on Adhesive Method of Veneering Composite

The aim of this study was to compare different methods for effective adhesion between a glass fiber-reinforced composite (FRC) material for framework and a veneering composite (VC) material for coating framework when fabricating clasps (FRC clasp (with VC)). Vectris pontic and EG fiber were used as FRC materials, the glass fibers of which were preimpregnated with resin. Palfique estelite LV was used as the VC material.Laminate specimens were fabricated by coating FRC with VC (Palfique⁄Vectris, Palfique⁄EG fiber). Five adhesion methods were used when coating the framework. Three specimens were prepared for each adhesion methods. Deflection and load when VC cracked were examined using the three-point flexural test. The mean and S.D. of each value were calculated and subjected to two-way analysis of variance (ANOVA) and multiple comparisons (Bonferroni⁄ Dunn) to determine the significance of the differences (P = 0.05 and 0.01) between the results of the respective methods.The deflection of Palfique⁄Vectris and Palfique⁄EG fiber was 0.497-0.631 and 0.426-0.481 mm, respectively, the load of which was 92.33-108.00 and 60.17-72.50 N, respectively. The deflection and load under all adhesion methods were significantly higher in Palfique⁄Vectris than Palfique⁄EG fiber (P<0.01). In Palfique⁄Vectris, deflection under non-adhesion was significantly lower than under others, but there were no significant differences among loads in different adhesion methods. In Palfique⁄EG fiber, there were no significant differences among deflections and loads in all adhesion methods.In the present study, the results suggested that sandblasting could be effective to increase the amount of deflection causing VC cracking in a clasp arm.