Objective Local anesthesia (LA) is widely used in dental treatment. Although the administration of LA agents is generally very safe, adverse reactions caused by LA are relatively common. The present study was performed to elucidate the possible causes and clinical problems occurring in cases of dental treatment-associated death under LA in Japan. Methods We reviewed possible cases of unexpected dental treatment-associated death under LA in Japan between 1951 and 2014. Cases of outpatients with unexpected death occurring during or after dental treatment under LA were included in the study. Results A total of 38 possible cases of dental treatment-associated death under LA in Japan were selected. Twenty-five of the patients (66%) had no definite relevant medical history or had an inadequate description of medical history. Thirty-six cases (95%) developed adverse events within 30 min of LA application. Emergency first-aid treatment was performed by the dentist in 50% of the cases. The possible causes of death were divided into three major categories: heart failure, cerebrovascular disorders, and anaphylaxis. Conclusions Unexpected dental treatment-associated deaths under LA were reported. It may be difficult to predict these adverse events before treatment from patient records. This study warns that severe adverse events or mortality are possible even during outpatient dental treatment with use of LA alone. A dentist is required to manage these situations. Also, mortality cases must be avoided with maximal reliability on the dentist.
