Initially exploited in archaeology, dental calculus is now revealing its potential in forensic science. It retains traces of ingested substances, opening the way to post-mortem analysis of drug intake and psychoactive compounds.
Dental calculus: A neglected but valuable matrix
Dental calculus forms through the gradual mineralization of dental plaque, a biofilm composed of saliva, microorganisms, and food residues. This process traps various compounds present in the oral cavity, including xenobiotics such as drugs or their metabolites. Its crystalline structure grants this matrix an excellent preservation properties for the substances it contains, while making it resistant to external degradation, including in post-mortem or archaeological contexts.
A new path for tracking illicit substances
Recently, a research team demonstrated the feasibility of a toxicological approach based on the analysis of dental calculus using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). In a study involving ten forensic cases, the researchers detected 131 substances in tartar, compared to 117 in blood—sometimes in higher concentrations within the tartar. The method enabled the identification of common drugs such as cocaine, heroin, and cannabinoids, even in cases where they were no longer detectable in conventional matrices (Sørensen et al., 2021). These substances, absent from the blood, were often present in higher concentrations in dental tartar.
A long-lasting and discreet witness
This approach offers several clear advantages. It allows the detection of substance use weeks or even months after ingestion. Tartar sampling is non-invasive and applicable to skeletal remains, making it particularly relevant in archaeological and forensic anthropology contexts. It can help reconstruct consumption habits, medical treatments, or causes of death in situations where blood, urine, or hair are unavailable.
A promising method to be further developed
One of the main strengths of this technique lies in its ability to exploit a matrix that is often overlooked but commonly available on teeth. Only a few milligrams are needed to conduct a reliable analysis—provided the trapped substances remain stable over time. This method also opens the possibility of broadening the range of detectable compounds, pending further validation.
While promising, this avenue still requires additional research to standardize protocols, assess the long-term stability of molecules, and fully integrate this approach into routine forensic toxicology practices. Although still in its exploratory phase, the method offers remarkable potential for the use of alternative matrices and opens new perspectives for forensic toxicology.
Reference:
- Sørensen LK, Hasselstrøm JB, Larsen LS, et al. Entrapment of drugs in dental calculus: detection validation based on test results from post-mortem investigations. Forensic Sci Int 2021; 319: 110647.
- Reymond C, Le Masle A, Colas C, et al. A rational strategy based on experimental designs to optimize parameters of a liquid chromatography-mass spectrometry analysis of complex matrices. Talanta 2019; 205: 120063.
- Radini A, Nikita E, Buckley S, Copeland L, Hardy K. Beyond food: The multiple pathways for inclusion of materials into ancient dental calculus. Am J Phys Anthropol 2017; 162: 71–83.
- Henry AG, Piperno DR. Using plant microfossils from dental calculus to recover human diet: a case study from Tell al-Raqā’i, Syria. J Archaeol Sci 2008; 35: 1943–1950.
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