Background Japan Sport Council (JSC) collects more than 1,000,000 injury data per year and provides medical benefits for injured students who got hurt under the supervision of school. From 2005 to 2014, JSC provided disability compensation for a total of 1,520 sports-related injuries. Baseball was the most common cause of injuries in youth sports, and 474 injuries occurred in extracurricular activities during the period. Kusumoto et al.¹ found that eye trauma in baseball was the most common and that 196 cases occurred (¹ K. Kusumoto, Y. Nishida, K. Kitamura, M. Oono, T. Yamanaka, and Y. Sugimoto, “An analysis of ocular injuries among youth baseball athletes utilising school insurance big data in Japan,” Safe Communities 2015 in Thailand, 2015). Kusumoto et al. also found that dental trauma was the second most common injuries in baseball. Therefore, in this study, we investigated dental injury among youth baseball athletes in Japan as a consecutive research.

Methods One hundred eighty-five injury cases were used for this research. First, we categorised these injuries by utilising JSC’s injury severity grading chart defined by the Ministry of Health, Labour and Welfare in Japan. Next, types of injuries in each severity category were clarified based on dentists’ diagnosis/evaluation.

Results These injuries consisted of four groups by the injury grading chart. The groups range from severe to minor condition as follows; 1) 1 case (severity), 2) 7 cases, 3) 29 cases, 4) 188 cases (minor). The types of injuries were as follows; 93 teeth fracture, 54 dislocation/subluxation of teeth, 15 pulpitis, 13 alveolar bone fracture, 12 periodontitis and so on. Additionally, the most dental trauma occurred at the central incisors of upper teeth, more than 110 cases.

Conclusion Baseball-related dental trauma is the second highest common injuries among youth athletes in Japan. Based on the results, we propose some preventive methods; 1) wearing a helmet attached a full face guard, 2) managing their practice fields where usually multi-groups practice at the same schedule, and 3) educating coaches, athletes, and parents with potential risks of broken teeth in baseball.