Bony Bridge Evaluation Following Alveolar Bone Grafting by Hounsfield Unit Visualization

Although alveolar bone grafting (ABG) is the standard treatment for cleft lip and palate with alveolar clefts, no studies have visually demonstrated the qualitative changes in grafted bones over time. In this study, the authors attempted to depict the changes in ossification of the grafted bone over time using color mapping based on differences in Hounsfield units (HUs). Alveolar bone grafting was performed in 7 cases. Computed tomography data procured ∼1 month before ABG, 1 day after surgery, and 6 months after surgery were extracted using Mimics (version 26.0)-a medical image analysis software. The difference in the HU values was visualized through color mapping in the axial, coronal, and sagittal planes, and changes in the HU values of the grafted bone over time and structure were observed. The HU values were high in all areas immediately after surgery; however, 6 months after surgery, cortical bone-like structures with high HU values were observed around the grafted bone, regardless of the presence of dynamic teeth changes. Moreover, the HU values were evidently high in areas where tooth movement was observed. Changes in the HU values over time can contribute to quantitative suggestions regarding the filling volume and filling pressure in ABG techniques and aid in determining the optimal orthodontic force most conducive to tooth movement during orthodontic treatment. Hence, this technique is expected to be valuable for both research and clinical practice.