Kabbashi SalmaChandler SusanSmith-Jacobs Jami Ashleigh2026-10-272026-10-272026University of the Western Capehttps://hdl.handle.net/10566/25731Substance use disorders remain a major public health and forensic concern globally and within South Africa, particularly in the Western Cape. Methamphetamine, methaqualone, and heroin remain highly prevalent and have devastating effects on communities of the Cape Flats, with links to violence, crime and fatalities. Conventional forensic toxicology matrices such as blood and urine are limited by short detection windows and rapid postmortem degradation. Mineralised dental tissues, particularly dentine, may provide a stable alternative matrix capable of preserving evidence of long-term substance exposure. However, research investigating isolated human dentine as a toxicological matrix remains scarce. To date, research reporting the detection of methaqualone in human dentine is notably absent. Furthermore, existing dentine toxicology research has been restricted to postmortem conditions, with no published studies utilising dentine from living participants or comparisons between active and past substance users to evaluate long-term substance retention within the matrix. Aim: The core aim of this exploratory study was to evaluate the feasilibility of isolated human dentine as a matrix for detecting methamphetamine, methaqualone, and heroin metabolites in active and past substance users in the Western Cape, South Africa, using Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS). Materials and methods: A total of 23 dentine samples were analysed from two participant cohorts: 18 past substance users were recruited from the U-Turn Homeless Ministry and 5 active substance users were recruited from the South African National Council on Alcoholism and Drug Dependence (SANCA). Dentine was isolated from extracted teeth, pulverised, solvent extracted, and analysed using UPLC-MS/MS.enTeethHuman dentineDental tissuesForensic odontologyForensic toxicologyThesis