Biomechanical features and fracture characteristics of mandible based on digital image correlation technique

Current understanding of mandibular biomechanics remains limited due to methodological constraints in characterizing full-field mechanical responses during trauma. This study employs Digital Image Correlation (DIC) Technique to quantify strain distributions and fracture thresholds during condylar axial loading, addressing gaps in correlating biomechanical loading patterns with clinical fracture. This study is a preliminary qualitative study. Six human mandibles (59.1 ± 6.2 years) without osseous pathology (CBCT-verified) underwent axial loading (0–600 N, 5 N/s) along the condylar axis using a Bose Electroforce 3520-AT system. Full-field strain and displacement were monitored via DIC. Destructive testing proceeded until mandible fracture, recording fracture thresholds and patterns. Under 600 N axial loading to the mental region, peak strain localized at the condylar head (1261 ± 388 μm/m, P < 0.001). The condylar head exhibited a statistically significant reduction in coronal axis displacement (0.055 ± 0.033 mm, P < 0.05). Compressive strains dominated anterior structures (the condylar head, anterior condylar neck, anterior mandibular ramus, and mandibular body), while tensile strains concentrated posteriorly (in the posterior condylar neck, condylar base, posterior mandibular ramus, and mandibular angle). Fracture initiation occurred at critical thresholds of 1895 ± 393 N load and 3.1 ± 0.6 mm displacement, with 66.7% (4/6) of specimens exhibiting concomitant fractures in the mental regions, mental foramen, and molar regions. Axial loading to the mentum-condylar induces maximum strain concentration at the condylar head, mandibular fossa constrains condylar displacement. The head of the mandibular condyle is most prone to fracture and is also prone to be accompanied by fractures in the mentum, mental foramen area, and molar region.