Cortical bone mineral density in asymmetrical mandibles: a three-dimensional quantitative computed tomography study

The three-dimensional distribution (3D) of the highest mineralized cortical bone was evaluated in 32 subjects between the ages of 8 and 30 years with asymmetrical mandibles using quantitative computed tomography (OCT). The ge ometrical distribution of the highest mineralized areas (> 1250 mg/cm(3)) r epresentative of mandibular cortical bone was determined by 3D reconstructi on of the images. The length of the mandible on each side was determined by defining a new linear measurement from the centre of the 3D reconstructed condyle to the midline of the symphysis as identified from a submental view . The cross-sectional areas of the masseter and medial pterygoid muscles we re assessed from bilateral axial views through the middle of the muscles pa rallel to the Frankfort-Horizontal plane. Comparison between the lengths of the two mandibular sides (right - left = mm) indicated a range of asymmetr ies with an equal number of subjects with the left and right mandible longe r. Comparison of the area of highest mineralized cortical bone between the rig ht and left sides (R/L) to the ratio of the mandibular length (R/L) showed a high correlation coefficient (r = 0.629) suggesting that the shortest man dibular side had more highly mineralized bone. A comparison of the area of highest mineralized cortical bone between the right and left sides (R/L) to the ratio of cross-sectional areas of the muscles showed the highest corre lation coefficient (r = 0.724) with the ipsilateral masseter muscle. These findings indicate that asymmetrical mandibles are associated with asymmetri cal distributions of the highest mineralized cortical bone and that this is age dependent.