ポテンショスタティック法による歯科用アマルガムの耐食性試験

The aim of this study was to examine the validity of a test method (report from ISO/TC meeting in London, October 1998, document N55) for the corrosion resistance of amalgam, considered for adoption as ISO (International Organization for Standardization) test. The corrosion resistance of six types of amalgam was evaluated using the proposed potentiostatic test (N55). The test procedure (N55) was found to be relatively simple and provide reproducible results. Therefore the proposed potentiostatic test can be justified as a standard test of corrosion resistance for dental amalgams

Effects of the development changes in dentition on the retention of mouthguards

Summary The use of mouthguards is one of the main strategies that are considered effective in preventing sports–related trauma.Although mouthguards are recommended for use in children during sports activities,little is known as to how growth and developmental changes in the oral cavity, jaw, and dentition affect the retention of mouthguards. In the present study, we designed mouthguards for primary,mixed(4 types),and permanent detention stages and performed tensile testing to determine the effects of dental growth and development on their retention.We also designed mouthguards for the left maxillary second milk molar,left maxillary second premolar, and left maxillary first molar to determine how the shape of the teeth affects their retention.Data was analyzed statistically,and the following results were obtained:1.Mouthguards for permanent detention stage had a significantly higher level of retention than those for primary and mixed detention stages.2.Mouthguards for primary detention stage had a significantly lower level of retention than those for mixed and permanent detention stages. 3.The retention of mixed detention stage mouthguards became poorer with the number of teeth requiring relief.4.Differences in the shape of the teeth(left maxillary second milk molar, left maxillary second premolar, left maxillary first molar)had no significant effect on the retention of mouthguards.These findings indicate that the level of mouthguard retention is lower in children at primary and mixed detention stages than in adults and children with complete eruption of central incisor to second molar.This difference may be attributed to the differences in the coverage areas of mouthguard