Here we investigated needlestick and similar injuries reported over a 10-year period between April 2004 and March 2014. The purpose of this study was to prevent recurrence and reduce the incidence of such injuries at Tokyo Dental College Chiba Hospital. The Division of Medical Risk Management at Chiba Hospital anonymized the data to protect personal information prior to analysis. A total of 213 injuries occurred over the 10-year period investigated, but the number of cases decreased yearly. Many cases involved dental undergraduate students and dentists, followed by trainee dentists, students at the school of dental hygiene, nurses, dental hygienists, and cleaners. Suture needles, followed by injection needles, were the top two most common injury-causing instruments, contributing to approximately 50% of the total number of such cases. Many injection needle injuries occurred during tidying up, while those caused by suture needles occurred during dental treatment. Taken together, these findings suggest the importance of strict adherence to guidelines provided in safety manuals on error-free procedures and handling of instruments. Improvement in the ability to sense potential risk is essential if such injuries are to be avoided.