A Pilot Study on the Deposition of Drugs in Dental Tissues as Alternative Matrices for Forensic Toxicology

Background: Teeth may serve as alternative matrices for post-mortem toxicological analysis. Al- though the mechanism of drug incorporation into dental tissues remains unclear, it is hypothesized that orally ingested substances can permeate dental enamel and reach dentin and the pulp. Objec- tives: This study investigated enamel permeability to commonly ingested drugs, considering mo- lecular characteristics (methadone - MET and dextromethorphan hydrobromide – DXM), pH, sugar content, and tooth conditions (intact enamel, cement-enamel junction-CEJ exposure, enamel wear). Materials and Methods: Sixteen clinically extracted teeth were divided into three groups and im- mersed in different substances, including MET with sugar, DXM with and without sugar (pH 4.5, 1 mg/ml), and acidified saliva (pH 5–6), simulating an addicted individual’s oral environment. Cyclic immersions (substance-saliva-substance) mimicked chronic drug intake for about six weeks. After treatment, each tooth was separated into enamel, dentin, and pulp, and analyzed using liquid-liquid extraction and LC-MS/MS. Results: Preliminary results showed that both MET and DXM can penetrate both the enamel and dentin, reaching the pulp regardless of tooth integrity or molecule type. Acid- ity and sugar content significantly increased the diffusion. Conclusions: These findings suggest that other substances orally assumed might be endowed with similar effects on dental tissues, especial- ly when combined with sugar or acid solutions, supporting teeth as viable matrices in post-mortem toxicology. However, pulp concentrations may reflect oral contamination rather than systemic levels