This study evaluated the cusp tip deflection of aluminium tooth models with a mesial-occlusal-distal (MOD) cavity filled with three bulk-fill resin-based composites (RBCs), Aura Ultra Universal (Aura), Admira Fusion x-tra Universal (Admira), and Filtek One shade A2 (Filtek One), to assess the level of shrinkage stress they could produce. The models were prepared using a primer, adhesive and a single RBC increment photo-cured for 20 s at a radiance exitance 1.25 W/cm². The RBC axial shrinkage strain (ε) and stress (S) were also measured. Micro-computed tomography in combination with silver nitrate infiltration showed no interfacial debonding. The mean cusp tip deflection for Admira was found to be smaller than those for the other two RBCs. Although ε and S for Aura were higher than those for Filtek One, their mean cusp tip deflections were not significantly different. These results could be explained by the temporal behavior of their elastic modulus.

This study aimed to evaluate the usefulness of light-cured resin coating restoration materials (RCs) on anterior composite resin blocks by quantifying the color, gloss, and surface roughness before and after toothbrush abrasion test and to evaluate the shear bond strength before and after thermal cycling test. Four types of RCs were used in the experiments. The application of RCs to composite resin blocks resulted in color changes and a decrease in gloss after the toothbrush abrasion test; however, both were within clinically acceptable limits. The surface roughness was at a value that made bacterial adhesion difficult both after the application of RCs and after the toothbrush abrasion test. The shear bond strength also had clinically acceptable bond strength. Therefore, the application of RCs to composite resins in the oral cavity is considered effective in terms of maintaining esthetics, gloss, and surface properties, as well as the durability of RCs.

A tongue-controlled intraoral pointing device for operating information and communication terminals, such as computers, which allows the wearer to perform oral training while typing, was developed. Its effectiveness was evaluated in healthy participants. There were no differences in typing speed for the same input between computers with any operating system/display combination. Typing with the developed device was performed at 80% of the speed compared to using a stylus pen held in the mouth, the conventional method used by persons with upper limb disabilities. Electromyography signals increased concomitantly by 1.8-fold in the buccal and 2.0-fold in the submandibular area. There was a 2.5-fold increase in saliva secretion and a decrease in salivary α-amylase activity to 40%, indicative of stress. The computerized operation of this device is expected to contribute to the prevention of oral frailty by maintaining and strengthening oral functions and hygiene.