Retrieval Analysis of Fractured Mandibular Reconstruction Plates Using Scanning Electron Microscopy

Mandibular reconstruction plates are widely used following segmental mandibulectomy, but plate fracture remains a significant complication. This study presents a retrieval-based protocol that uses scanning electron microscopy (SEM) to characterize fracture morphology and to infer site-specific mechanical failure directions in titanium mandibular reconstruction plates. We hypothesized that fracture-surface orientation would differ by anatomical fracture location and would exhibit qualitative similarities to reference fractures produced under different loading directions. Seven patients with fractured plates were identified, yielding nine fracture sites. Retrieved plates were cleaned, mounted, and examined by SEM to identify crack initiation sites, fatigue striations, beach marks, and final rupture zones. Energy-dispersive X-ray spectroscopy was performed to assess elemental composition and exclude corrosion-related abnormalities. Two unused reference plates were manually fractured under simplified bucco-lingual and superior-inferior loading, and their fracture-surface features were qualitatively compared with those of the clinical specimens. All six body-region fracture sites showed predominantly bucco-lingually oriented fracture-surface features, whereas the three mandibular-angle fracture sites showed predominantly superior-inferior orientation. Body-region fractures shared selected morphological features with the bucco-lingual reference fracture, while angle-region fractures showed similarities to the superior-inferior reference fracture. Energy-dispersive X-ray spectroscopy detected primarily titanium and oxygen, with no marked unexpected deposits or compositional abnormalities. These findings suggest that the mechanical environment of mandibular reconstruction plate failure may differ by anatomical subsite. However, because the reference experiments used one specimen per loading condition, relied on manual, unquantified loading, and included no cyclic fatigue testing, the observed similarities should be considered qualitative and hypothesis-generating rather than definitive evidence of causal loading mechanisms. Further quantitative biomechanical and computational studies are needed before subsite-specific plate design or reinforcement strategies can be recommended.