Differences in volume and surface of mandibular condyles in Caucasian adult subjects with low, normal or high mandibular plane angle

Object: The aim of this study was to evaluate the condylar volumes in a group of patients aged between 15 and 50 years old. They were pre-orthodontic asymptomatic patients with different facial structure (low mandibular plane angle, normal angle, high angle). The evaluation of the volume of facial structures became recently important because the volumetric value of a solid can describe, in only one number, the data on the form and surface of the object, bearing in mind also the hollow structures (nasal cavity, sinus, oral cavity). The evaluation of the volume of facial structures is today possible through the segmentation of structures within the 3D reconstructions. Materials and methods : We examined Cone Beam data of 60 young adult caucasian subjects with different facial structures (low angle, high angle, normal angle) before they were scheduled to undergo orthodontic treatment for dental problems of overcrowding. The criteria for inclusion of patients were the absence of TMD symptoms, of tooth agenesis, of previous Ortognathic surgery, of posterior occlusal stop, and extreme brachycephalic and dolichocephalic. The cephalometric analysis on Cone Beam data was performed with Dolphin 3D on DICOM files. The calculation of volume and condylar surface was done with the software Mimics, through the technique of segmentation. Results: By dividing the sample into three groups (high angle, normal angle, low angle) we highlighted statistically significant differences in volumes and areas of right and left mandibular condyles within the types of facial divergence. The low angle subjects showed a significantly greater volume and condylar surface than the other two groups. In the three groups, the values of the areas showed a standard deviation and a range higher than the other 2 groups. Discussion: The observed differences could be related to different muscle tone of the masticatory muscles. in another study F. Festa et al (2006) observed how the sEMG activity of the masseter, the anterior temporal, and of the upper trapezius and posterior cervical at mandibular rest position was higher in low angle subjects as compared to high angle and normal angle subjects. This higher sEMG activity may be responable for the volume of the condyle. Conclusions: There is evidence of an association between volume and mandibular divergence. For all groups, values that indicate the condylar surface showed inter-individual variation higher than the values indicating the condylar volume and this result could be associated with the presence - on the condylar surface - of microscopic anfractuosity (small pits, furrows, various irregularities) that are able to influence the measurements of the condylar surface, but are not able to significantly influence the measurements of the condylar volume