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One hundred cases of squamous cell carcinoma in oral and maxillofacial regions, including 50 fresh samples and 50 paraffin-embedded blocks, were examined with the use of Flow-cytometry (FCM) for DNA content of tumour cells, changes in ploidy, and kinetics of tumour cells. The results showed that: the average DNA Index (DI) was 1.154; the incidence of heteroploidy was 59%; and the S-phase cell proportion (PI) was 22.62%. Following the advance of tumour, as assessed by clinical stage and pathological grade, the rate of heteroploidy, DI and PI increased markedly. The results demonstrate that FCM can be utilized as an adjunct method for pathologic diagnosis with particular importance in the evaluation of malignant grade of neoplasms.

A retrospective study of 68 patients was carried out to assess the complications arising from the use of reconstruction plates in the maintainance of space and contour following mandibular segmental resection. Skin or mucosal perforation, plate fracture and loss of screw retention were the main complications. The most susceptible sites to screw loosening in the plates were situated nearest to and farthest from the resection margin on the proximal residual segments. Some of the possible causative biomechanical mechanisms of plate failure were studied using photoelastic models simulating the types of mandibular defect and plate fixation. Isochromatic fringe analysis was used to analyse stress lines in the bone surrounding screws. It was found that, during functional loading, moment and shear forces produced high concentrations of squeeze and press stress in this bone, causing bone resorption with consequent loss of screw retention.