In this study, glass fiber-reinforced thermoplastic（GFRTP）for non-metal clasp denture（NMCD）materials was fabricated, and its frictional wear properties were evaluated using a ball-on-disk frictional wear device employing a rotating wheel. Using an NMCD injection molding machine, GFRTPs composed of polypropylene and E-glass fiber with fiber contents of 0, 10, and 20 mass％（GF0, GF10, and GF20）were prepared, respectively. Two commercially available NMCD materials and two available acrylic denture base materials were used as controls. As a result, the coefficients of friction of GFRTPs and NMCDs were significantly lower than that of POLY BASEⅡ（PB）as an acrylic denture base material. Moreover, wear widths of GF0 and NMCDs were significantly larger than that of PB. Furthermore, it was indicated that the frictional wear properties of GFRTPs with fiber contents ＜20 mass％ are not significantly affected by adding fibers. Meanwhile, it was confirmed that there are negative correlations between the wear width on the surface of GFRTPs after the frictional wear test in the present study and mechanical properties of the GFRTP surface obtained in a previous study.

In recent years, brackets made of zirconia have been frequently used for orthodontic treatment, and so a bracket with a newly designed base was fabricated to make debonding possible with almost no scratching of the tooth surface, and the properties related to adhesion were investigated. For comparison with this new bracket（IBr）, a conventional bracket（ZBr）was adopted. The shear bond strength and fracture type were investigated with regard to the type of cement, thermal shock, and direction of debonding. As a result, compared with ZBr, the shear bond strength of IBr decreased with all cements after thermal shock. In particular, it was found that debonding at the interface between the tooth surface and cement could be easily facilitated applying a load perpendicular to the tooth axis. Therefore, IBr is considered to be a bracket that can be debonded while minimizing scratching of the tooth surface.