Challenges of the minimum postmortem interval (PMImin) estimation in forensic scenarios: Is dental histology an alternative?

Postmortem interval (PMI) estimates the time since death. Teeth are perennial elements capable of remaining intact in taphonomic environmental circumstances. The objective was to evaluate the feasibility of estimating the minimum postmortem interval (PMI_min) through histological analyses of dental tissues exposed to burial and drowning conditions, simulating common scenarios in forensic practice. A total of n = 99 teeth were analyzed and divided into four groups: control (T0), one month (T1), three months (T2), and six months (T3). The control sample comprised 10 teeth, while T1, T2 e T3 were divided into three different subgroups: controlled environment, buried, and drowned. For each subgroup, ten samples were used. Following exposure to taphonomic conditions, the specimens were processed, and histological sections were obtained. The two-way ANOVA test and the Tukey’s post-hoc test were employed for the quantitative analysis of dentin collagen fibrils, revealing statistically significant differences (α = 5 %). This allowed for the estimation of the PMI_min at three months by observing pixel counts exceeding 13e+05 in drowned teeth and greater than 8e+05 in buried teeth. Qualitative analysis revealed that the PMI_min of drowned teeth was estimated at one month due to the absence of the periodontal ligament (PDL) and at six months due to the absence of predentin and partial degradation of the cementum. For buried teeth, the three-month PMI_min was indicated by the absence of PDL and partial cementum degradation. The absence of pulp and remnants of predentin characterized the six-month PMI_min. Qualitative and quantitative histological characteristics and parameters are potential to estimate PMI_min in forensic scenarios spanning up to six months.