Determinazione post-mortale dell’uso e dell’abuso di droghe sui tessuti dentari

Background: Post-mortem toxicology constantly deals with the research of reliable alternative matrices useful for pathologists in cases in which the classic matrices for forensic toxicology [in particular blood and hair] are not more available (e.g. carbonized or skeletonized corpses, human remains, exhumed bodies, etc.). Teeth can be applied as an alternative matrix since they are highly resistant, available, and stable after death. Dental enamel, dentine or pulp could disclose acute or chronic drugs assumption, given the different tissues constitution.The previous literature does not provide information on the pharmacokinetics of substances and on the mechanism and site of incorporation of xenobiotics into dental tissues. Scope: This pilot research aims to investigate whether in the pulp can be detected the same substances found in blood in drug related death cases. Secondly the study aims to disclose possible deposited drugs in the hard tissues of the tooth (dentine and/or enamel), the related degrees of accumulation in different dental tissue, thus contributing to reconstruct the drug abuse history (timing, e.g.) . Materials and Methods: The study experimented with a novel method to separately analyse enamel, dentin, and pulp tissues, that was applied to 10 teeth collected during autopsies of drug-related deaths along with blood and hair samples for classic toxicological analyses. Each tooth was prepared by the same forensic odontologist using diamond and multi-blade burs on a turbine above an amalgam aspirator coated with filter paper. Teeth were divided into two longitudinal halves and pulp was extracted from the chamber and roots. The enamel was separated from the coronal dentin by pulverization. The coronal secondary dentin was separated from the primary dentin pulverizing an inner layer of approximately 1,5 mm coronal and 1 mm cervical thickness. The residual outer coronal dentin was separated from the roots by pulverization and then the roots were pulverize with a hammer. Each dental tissue was extracted with acid for cocaine, opiates, and metabolites and analyzed by gas chromatography (GC) and liquid chromatography with high-resolution mass spectrometry (HR-MS). The results were then compared with those obtained from blood and hair samples. Results: Preliminary results demonstrated that teeth are different from any other classic matrix (blood and hairs) and the qualitative correlation in detecting substances between pulp/blood and dental hard tissues/hair suggests that they can be useful in post-mortem evaluation for both acute and chronic assumptions of drugs. The most significant result is that the mechanism of accumulation of substances in mineralized tissues seems to be influenced by the type of 4 molecule and the method of assumption. The innovative method for dental tissues separation is absolutely promising to study the different accumulation of substances in teeth, possibly disclosing both acute and chronic assumption in forensic cases of drugs related cases. The main limitation of this study is the in vivo experimentation, since the study is based on teeth extracted for toxicological purposes in cases of real drug-related deaths. This factor determines not only a limited availability of the sample, but also an uncontrollable variability on the nature of the substances detected and, above all, the absence of anamistic information of the subjects to compare the results in dental hard tissues with the time, rates and method of assumption during life. Further research is necessary to systematically investigate the distribution of different substances within the mineralized tissues of the tooth. It seems appropriate to improve the sample relating to cocaine intake in order to create a statistical linear regression model between the quantity detected in the dental pulp and in the peripheral blood. Finally, we should proceed with the preparation of a research project that includes the study of teeth extracted from living subjects in dental care (for clinical reasons) with a known and documented history of chronic substance intake to delve deeper into the meaning of accumulation within dental hard tissues.