Forensic medical diagnosis of hidden crown microcracks caused by forced jaw clenching

The aim of the study was to establish diagnostically significant morphological and biomechanical criteria of hidden microcracks of the tooth crown formed during forced jaw clenching, enabling reconstruction of the mechanism, direction, and intensity of compressive loading. Methods. Macro- and micromorphological analyses of hard dental tissues were applied, along with morphometric assessment of microcrack parameters and modeling of controlled axial occlusal loading followed by comparison of experimental and expert specimens. The analysis was based on the study of spatial orientation, depth, and density of microdamage in enamel, dentin, and the dentinoenamel junction. Results. Characteristic damage patterns were identified, including subsurface enamel microcracks of radial and oblique orientation, concentration of defects in the dentinoenamel junction area, and deformation changes in the dentinal tubular structure without destruction of the organic matrix. Enamel microcrack length ranged from 0.4 to 2.1 mm, their propagation depth reached 80–240 μm, and dentin involvement varied from 0.3 to 1.2 mm. The spatial configuration of damage reflected the direction of the applied force and occlusal relationships. The practical significance of the study lies in the possibility of using the identified morphological and morphometric features as objective forensic medical criteria in the expert assessment of dentoalveolar injuries. The obtained data increase the accuracy of reconstructing the trauma mechanism and differentiating violent jaw clenching from other types of mechanical impact. The results may be applied in forensic medical and forensic dental examinations, as well as in the development of methodological guidelines and diagnostic algorithms for hidden crown injuries. Conclusions. Hidden microcracks of the tooth crown form a stable morphological “imprint” of compressive loading, allowing reliable differentiation of this trauma mechanism from impact and chronic overloads. A comprehensive analysis of morphological and quantitative features enhances the objectivity of forensic medical assessment of dentoalveolar injuries in the investigation of violent acts against the person.

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