Effects on oral tissues of asphyxiation caused by cervical compression: The pink teeth phenomenon in Kato's studies (1941)

The effects on oral tissues of asphyxiation caused by cervical compression were investigated in 203 rabbits by Kiyotoshi Kato, who published four papers in classical Japanese in Kokubyo Gakkai Zasshi (now The Journal of the Stomatological Society, Japan) in 1941. The aim of this review is to summarize and disseminate the enormous amount of experimental data (reprint permission in English has been obtained from the journal). Based on the experimental models of hanging, strangulation with an external force equal to body weight, and strangulation with an external force equal to 1/10th body weight, the macroscopic and histological findings of the oral region immediately after death, including the respiratory condition until death and ocular conjunctival petechiae, were obtained and compared with 4 cases of human strangulation. Strangulation after each of four physical conditions (anesthesia, starvation, alcohol intake, and bleeding) was also investigated. Experiments were performed to investigate the effects of tracheal obstruction, cervical vein ligation, common carotid artery ligation, cervical nerve amputation, or combinations thereof. In the discussion focusing solely on tooth discoloration, it was suggested that the presence of pink teeth at a stage when putrefaction has little or no effect might be a finding indicative of death from asphyxiation caused by cervical compression. This review provides detailed data on the condition of oral tissues after asphyxiation caused by cervical compression and is expected to be used not only for elucidating the mechanism of the pink teeth phenomenon but also for conducting other forensic research.