Three-dimensional evaluation of musculoskeletal in Class II and Class III patients.

OBJECTIVE: To evaluate and compare dimensional morphology of masseter and medial pterygoid muscles and mandibular skeletal parameters between subjects with skeletal Class II and Class III. MATERIALS AND METHODS: The sample consisted of 13 patients with skeletal Class II and 10 patients with skeletal Class III prior to the start of combined orthodontic treatment and orthognathic surgery with correspondence to definite inclusion and exclusion criteria. Magnetic resonance imaging was performed for mandibular muscles and following 2D and 3D measurements were done: cross-sectional area (CSA), thickness, width, longitudinal dimension and volume. 3D multi-slice computed tomography investigation was performed for the assessment of skeletal mandibular parametres and following measurements were done: height of mandibular ramus, length af mandibular corpus, overall mandibular length, intergonial width. All the measurements were done bilaterally. Data were analyzed using descriptive statistics, t-test, and correlation coefficients. RESULTS: It was found that values of all mandibular and medial pterygoid measurements were higher in Class III subjects with statistical significance (p<0.05). There was a tendency of all masseter variables to be higher in Class III patients. Positive correlations were found between muscles' volume and CSA in both groups, muscles' volume and all mandibular parameters in Class II group, CSAs and all mandibular variables except intergonial width in Class II group. Overall symmetry was observed between left and right sides in all muscular and mandibular measurements in both groups. CONCLUSIONS: The data were acquired using two different imaging techniques - MRI and MSCT that can be mentioned as a novelty in this field of research. Remarkable differences were observed between study groups for both skeletal and muscular measurements.

Three-dimensional evaluation of TMJ parameters in Class II and Class III patients.

The aim of our study was to assess condylar parameters and condyle position within glenoid fossa of TMJ in volumetric 3D imaging in patients with Class II and Class III malocclusions. MATERIALS AND METHODS. The study group included 15 patients with severe skeletal Class II (mean age 18.0 yrs) and 14 patients with severe skeletal Class III ( mean age 19,2 yrs) with an indication for combined orthodontic and orthognathic treatment. CT examination was performed, pictures were reconstructed in three - dimensional (3D) rendering and measured in two dimension projection (2D) pictures using IAC review and Transparent bone programs to quantify following condylar and glenoid fossa parameters - glenoid fossa width and height; tuberculum articulare angle; anterior, superior and posterior joint space; height and width of condyle, height of procesus condylaris. Mean values were calculated separately for left and right side. Differences of the mean values were tested using paired t-test. RESULTS. There were statistically significant differences (p<0,05) between two study groups for all spatial measurements on both sides with larger spatial measurements in patients with Class II malocclusions. Also the height of procesus condylaris varied between groups with statistical difference. Unilateral differences were detected for width of fossa glenoidale and height of condyle. CONCLUSION. Results show that there are a tendency for smaller condyle and wider spaces between condyle and walls of glenoid fossa comparing TMJ of Class II with Class III patients.

Condylar and mandibular morphological criteria in the 2D and 3D MSCT imaging for patients with Class II division 1 subdivision malocclusion.

UNLABELLED: The condyle has a special multidirectional capacity for the growth and adaptive remodeling of temporomandibular joint (TMJ). Being part of TMJ structure, it plays an important role in the stability of long-term treatment results for orthodontic and orthognatic patients with Class II division 1 subdivision malocclusions. Several computed tomography (CT) investigation modes have been used to evaluate the craniofacial morphology and particularly, for TMJ. Dimensional images, acquired using new generation multislice CT (MSCT) and cone beam CT scanning data, are becoming increasingly popular in the clinical work and research. The aim of the study was to develop a new CT investigation protocol for the quantification of morphological structures and skeletal landmarks of condyle, procesus condylaris and mandible. For this purpose we created two dimensional (2D) and three dimensional (3D) reconstruction images from primary axial MSCT scans using IAC review and Transparent bone programms and acquired accordant measurements of condylar and mandibular structures. This technic allowed to get truly volumetric reflexion of the joint components in its real anatomical size and avoided the bony superimpositions. Our material included 12 patients with skeletal Class II division 1 subdivision malocclusion who had indications for combined orthodontic and orthognatic treatment. CT examination was performed before the start of treatment. For statistical analysis paired Student t-tests were applied to test the diferences of mean values and correlation coefficients were calculated to assess possible interrelations between measurements. The preliminary results showed weak corrrelation between condylar and mandibular measurements. More significant correlation was observed between procesus condylaris and mandible. It was a significant difference between right and left side in the height of procesus condylaris in patients without clinicaly relevant facial asymetry which could be considered in the individual planning of orthognatic treatment. CONCLUSION: The developed combined 2D and 3D MSCT investigation protocol for condylar and mandibular measurements provides precise and demonstrative quantitative images of condylar and mandibular structures and its dimensional relationships., which could be qualified as informative criteria for the individual treatment planning for patients with Class II division 1 subdivision malocclusion.