Forensic potential of toothbrush derived DNA: A narrative review on human identification

Abstract

Human identification is a cornerstone of forensic science, encompassing both the confirmation of unknown individuals and the linkage of biological material to known persons. Although DNA profiling remains the gold standard for individual identification due to its exceptional discriminatory power, its application is frequently constrained by the unavailability of direct reference samples. This limitation has driven growing interest in alternative DNA sources derived from personal items encountered in daily life. Among these, the toothbrush has received particular attention, as its bristles routinely retain buccal epithelial cells and salivary residues that may yield sufficient human DNA for forensic profiling. This narrative review synthesizes the available literature on the use of toothbrushes as a DNA source within the context of forensic personal identification, with specific attention to extraction methodologies, factors influencing DNA recovery including toothpaste-mediated PCR inhibition, rinsing intensity, storage duration, and oral health status. The review further addresses the potential interference of the oral microbiome, the forensic challenges posed by mixed DNA profiles and secondary transfer, the applicability of contemporary techniques including massively parallel sequencing and probabilistic genotyping, and the integration of toothbrush-derived DNA into disaster victim identification protocols. Although complete and interpretable short tandem repeat profiles have been obtained across multiple studies, the primary evidence base remains limited to a small number of studies with heterogeneous methodologies and modest sample sizes. Standardized collection and extraction protocols have not yet been established. Future research should prioritize inter-laboratory validation, the systematic evaluation of oral health variables, and the integration of toothbrush sampling into evidence-based forensic frameworks.