A novel approach, exploring subgingival temperature changes over time since death: An animal study.

Abstract

Background: Accurate estimation of the postmortem interval (PMI) is a crucial aspect of forensic investigations. Traditional methods rely on rectal temperature measurement, but alternative sites may provide more reliable measurements under certain conditions. The subgingival region, being a well-insulated anatomical site, has been considered for temperature-based assessments. However, no studies have explored its viability in PMI estimation. This study aims to assess subgingival temperature changes before and after euthanasia in rats and rabbits and compare them with rectal temperature variations. Understanding these temperature shifts could help clarify the forensic relevance of subgingival temperature as an alternative or complementary method for PMI estimation.

Objective: To evaluate pre-euthanasia and posteuthanasia changes in subgingival and rectal temperatures in rats and rabbits.

Materials and methods: Based on a pilot study, the sample size was calculated (n = 8), comprising four rabbits and four rats. Following ethical clearance, a specialized subgingival thermometer was designed for measuring subgingival temperature, whereas rectal temperature was recorded using a commercially available digital thermometer (Omron MC-246 Digital Thermometer). Pre-euthanasia subgingival and rectal temperatures were recorded, followed by a second measurement taken 10 min posteuthanasia. The obtained temperature values (°C) were subjected to statistical analysis using the Wilcoxon signed-rank test and Spearman's rank correlation.

Results: Subgingival temperature before euthanasia was the only statistically significant finding (P = 0.010). In rats, a strong pre-euthanasia correlation between subgingival and rectal temperatures (r = 1.000, P = 0.010) weakened markedly after death (r = 0.200, P = 0.800). Conversely, rabbits exhibited a moderate correlation before euthanasia (r = 0.600, P = 0.400), which strengthened postmortem (r = 0.800, P = 0.200), indicating species-specific variations in heat retention and dissipation after death.

Conclusion: Both subgingival and rectal temperatures decreased after euthanasia, confirming a postmortem temperature decline. However, the results were not statistically significant due to the small sample size. With further research overcoming these limitations, subgingival temperature could serve as a potential alternative for PMI estimation.