Maxillary bone deformation in patients with leprosy: a novel method for quantitative evaluation by CT scan

 The facial deformity is one of the serious sequelae of leprosy, and the morphological changes of the bones in maxillofacial area were known as “facies leprosa” or “rhinomaxillary syndrome”. Even though these findings had been reported in the previous paleopathological and clinical reports, it has been difficult to quantify the severity of the maxillary bone deformities especially for those living. In this study, three-dimensional bone images of maxillofacial area were reconstructed from CT scan data and the deformities in maxilla were evaluated both qualitatively and quantitatively. The anterior-posterior length of the maxilla and the cranium were virtually measured on the median sagittal plane, and the ratio was calculated to compensate the individual differences in size of the cranium. As results, the ratios indicated the severity of the bone defects of maxilla, that is, the larger the loss, the smaller the ratio. Also, by comparison with the values of the control cases, it became possible to calculate the thickness of the maxillary bone defect individually. This is a novel method for measuring the maxillary defect, and may become a useful tool to estimate the thickness of the prosthesis required for reconstructive surgery.