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. Although 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.

Objectives: This study investigated enamel permeability to commonly ingested drugs, considering molecular 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 immersed 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. Acidity 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, especially 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.