The aim of this study was to evaluate the mechanical properties of hybrid resin blocks for the CAD/CAM crown. Eight kinds of hybrid resin block were used. To investigate the biaxial flexural strength, the two-body wear and dynamic hardness tests were performed, and the inorganic filler content was measured. As an additional experiment, the biaxial flexural strength was subjected to 8,000 thermal cycles between water baths kept at 5℃ and 55℃. Data were analyzed using one-way ANOVA and Tukey’s method. The correlation with the inorganic filler content was analyzed using Pearson’s correlation coefficient. As a result, mechanical properties were different for each hybrid resin block, and there was a significant difference in the inorganic filler content between all hybrid resin blocks. There was a negative correlation between the inorganic filler content and wear, and a positive correlation between the inorganic filler content and hardness, but there was no correlation between the inorganic filler content and flexural strength.

In this study, we evaluated the characteristics of a novel dual-cured resin-based luting agent（MAM-007）developed to reduce wear. MAM-007 containing silica filler with an average particle diameter of 300 nm and four commercially available resin-based luting agents were subjected to various tests ［basic properties test, wear test（Three body wear test, Collision wear test）］. The obtained values underwent statistical analysis.The filler content of MAM-007 was significantly lower than that of the other luting agents（p＜0.05）, the amount of water absorption was higher, the film thickness was thinner, and the surface hardness was lower. However, the three point bending test results showed the same strength as the other luting agents, and the bonding strength was equal to or greater than that of the other luting agents. In the wear test, the amount of wear was significantly lower than that of the other luting agents.It was suggested that the novel resin-based luting agent has basic properties equivalent to those of commercial resin-based luting agents and shows a lower amount of wear.

The L&H® titan arch wire（LH）is a superelastic Ni-Ti alloy wire with low-stress hysteresis. In this study, the 3-point bending property of newly developed LH rectangular wire with a 0.020×0.025-inch cross-section（LH20×25）was compared with that of seven other wires including current LH products.LH20×25 showed a superelastic property including stress hysteresis similar to current LH products that have smaller cross-sections in the 3-point bending test. Therefore, orthodontists could use the new LH wire in the same way as the current LH products to apply a larger orthodontic force. In addition, the bracket-slot play of LH20×25 in the bracket slot with 0.022×0.028 inches was estimated to be less than half of thet of the current LH products. Consequently, it could be applied to the finishing stage, in which accuracy and rigidity are required. In conclusion, it was suggested that LH20×25 could expand the application of LH wires to the finishing stage.