Post-mortem Interval and Its Relation with the RNA Degradation in the Dental Pulp in Submerged Teeth

Abstract

Post-mortem interval is the time between death and the discovery of the body or human remains. Teeth are the most resistant structures of the human body, able to withstand extreme conditions such as high temperature, humidity, and post-mortem degradation. The objective of this study was to evaluate the applicability of the method of quantifying degradation of RNA extracted from dental pulps to estimate the post-mortem interval, by simulating drowning conditions with teeth submerged in fresh water and exposed to different time intervals.

The sample consisted of 80 human teeth (third molars), divided into eight groups, and placed in the aquatic environment, for pre-established periods of three days, and 1, 2, 3, 4, 8, 12 and 16 weeks respectively. After the stipulated time, the teeth were removed and the RNA was extracted form the dental pulp. Finally, the RNA was electrophoresed and its Integrity Number (RIN) was calculated for each RNA pulp sample.

After the analysis, significant amount of dental pulp degradation was observed showing a RNA RIN of 6.50. The 18S/28S ribosomal RNA ratio was null (with a value of zero), and only in sample, it was extremely low (0.8). The fact that the samples were submitt to the environment associated with that the low proportion the18S/28S ribosomal RNA found in the samples, may be essential factors to justify the results obtained.

RNA degradation quantification method was not applicable, since it was not possible to establish a relation between the degradation of the RNA molecule and the estimation of the post-mortem interval.