Abstract: PURPOSE: Using impact test to study energy absorption ability of mouthguard splints of different thickness and materials. METHODS: In this experiment, group 1 was BIOPLAST 5 mm splint, group 2 was BIOPLAST 4 mm splint, group 3 was BIOPLAST 3 mm splint,group 4 was BIOPLAST 2 mm splint and group 7 was BIOPLAST 1 mm splint. Group 5 was ERKOLOC-PRO 2 mm splint, group 6 was DURAN 2 mm splint. Mouthguard splints were clashed by impact head from different heights. Digital Image Correlation System was used to record the process of the test. Images were transferred to data processing software, to analyze incident speed, incident depth and rebound height of the impact head. Absorbed energy and energy absorption ratio were calculated to analyze energy absorption ability of mouthguard splints of different thickness and materials. The data were analyzed using SPSS 22.0 software package for one-way analysis of variance and LSD. RESULTS: The higher impact head fell, the larger energy absorption ratio was. There was significant difference among group 1, 2, 3, 4, 7 in average energy absorption ratio（P<0.05）, and group 7 was the largest. There was significant difference among group 4, 5, 6 in average energy absorption ratio（P<0.05）, among which group 4 and group 5 were larger. CONCLUSIONS: 3 mm splint is good enough to be used to make mouthguard, which is also thinner and more comfortable. Splint of soft material is more suitable for mouthguard than splint of hard material.

Key words: Mouthguard, Impact test, Energy absorption