Study on the Mechanism of the Pink Tooth Phenomenon Using Bovine Teeth: A Pilot Study.

The pink teeth phenomenon has occasionally been observed in forensic autopsies. This study aimed to establish an experimental pink tooth model and an objective color tone evaluation method in order to clarify changes in the color tone of teeth and the relationship with hemoglobin monoxide and its decomposition products and with red pigment-producing bacteria, under various external environmental factors. It was confirmed that the color tone evaluation with ΔE and the L*C*h color space was useful. The results of various examinations using this model showed that color development was suppressed under aerobic conditions, faded early under light, became bright red under a low temperature and showed a tendency to be reddish at 3 days under high humidity and in the presence of soft tissue. The biochemical analysis revealed a significant increase in carboxyhemoglobin at 7 days and a tendency toward increasing the total heme pigment and bilirubin levels over time. The bacteriological analysis revealed that red pigment-producing bacteria increased over time but that the color faded after 7 days. These results suggest that putrefaction greatly affects the pink teeth phenomenon, whereas red pigment-producing bacteria have little effect on the occurrence of pink teeth. However, further studies are needed to clarify bacteriological involvement.

Comparison of racemization rates between vital and endodontically treated teeth for age estimation.

Amino acid racemization of dentin (AAR) is among the most precise methods for age estimation in unidentified adult cadavers. Although vital teeth are generally used for this technique, cases often have endodontically treated (Endo) teeth only. Therefore, the aim of this preliminary pilot study was to determine the applicability of Endo teeth by comparing AAR rates between vital and Endo teeth. Thirty-six dentin samples from vital teeth and 18 dentin samples from Endo teeth were analyzed, including the maxillary first premolar, maxillary second molar, and mandibular second premolar. Standard calibration curves for the mandibular second premolar and maxillary second molar were compared among vital teeth, Endo teeth, and mixed vital/Endo teeth. Discrepancies between estimated and actual ages were assessed by analyzing the AAR rates for the maxillary first premolar between vital and Endo teeth. The AAR rates for Endo teeth were higher than those for vital teeth in both the mandibular second premolar and maxillary second molar, and the correlation of the standard calibration curve for vital teeth only was highest (r = 0.982836; r = 0.92011467), followed by mixed (r = 0.949579; r = 0.76158) and Endo teeth only (r = 0.896082; r = 0.744991). In the maxillary first premolar, discrepancies were more than 10 years for all 5 Endo teeth, based on the standard calibration curve of vital teeth. The present study suggests that the AAR rates for Endo teeth might be affected by variation in dentin structure between vital and Endo teeth.

Sixty-eight cases of postmortem pink teeth observed in dental autopsies of unidentified cadavers.

The pink teeth phenomenon was first reported in people who died by hanging or drowning in 1829. In recent years, there have been many reports that the occurrence of postmortem pink teeth is closely related to the condition of surroundings and time after death rather than to the cause of death, as had previously been thought. We observed pink teeth in 68 of 324 unidentified cadavers autopsied during 2015-2021, and we investigated the relationship of pink teeth with age, sex, cadaveric condition, time after death, tooth type, and cause of death. The results showed no significant differences in the occurrence of pink teeth according to sex or place of discovery (indoors, outdoors, or in water). Pink teeth tended to be observed below the age of 60 years. In the 68 cases with pink teeth, 29.1% of all vital teeth were affected, with the anterior teeth being most common. No evidence was found that supported an association between pink teeth and cause of death. These results are largely consistent with recent reports on postmortem pink teeth. As it stands, the pink teeth phenomenon may be nonspecific and must not be misinterpreted in medico-legal investigations. This case series provides further evidence supporting recent reports and contributes to clarifying in greater detail the mechanisms of the coloration and fading of pink teeth.