| bjective: Scissors bite is common in orthodontic clinics.It showsmorphological abnormality, often accompanied with dental disfunctions andtemporomandibular disorders(TMD),which causes difficulties for treatment.This study was performed to make a contrast analysis.A sample of15Angleclass I malocclusion patients with unilateral scissors bite was compared with amatched group of12subjects without scissors bite through scanning themorphology of condyle, morphology of the glenoid fossa and joint spaces bycone beam computer tomography (CBCT),to better understand the skeletalmorphological characteristics and to investigate preliminarily whether they willbe affected by posterior scissors bite.we also intended to study the jointmorphology and the symmetry of condyle position between Angle class Imalocclusion patients with unilateral scissors bite and those without scissorsbite and to study the effects of gender and age on temporomandibularjoint(TMJ).This paper aims to try to give a clear and correct understanding ofscissors bite-------whether skeletal morphology of TMJ will be affected byposterior scissors bite,thus providing a theoretical basis of clinical diagnosisand treatment of it.Methods:15cases of Angle class I with unilateral scissorsbite as the experimental group and12cases without scissors bite as the control group were scanned by CBCT(All patients were from orthodontic clinic in theStomatological Hospital Affiliated to Luzhou Medical College during2010-2012). Image Reconstruction were done by Dental Volume ReformatFunction of Software Ondemand3D,and the required reference planes wasselected.Then measured the distance between the condyle center andmid-sagittal line,condylar longitudinal distances and horizontal angle ofcondyles on the selected axial images. Measured the gradient of articulartubercle,the vertical height the articular tubercle, the height of the condylarprocessus, height and width of glenoid fossa on the selected sagittalimages.Measured the value of long axis of condyle at the selected obliqueposition parallel to the long axis of condyle and the value of short axis ofcondyle and the anterior, superior and posterior joint space at the selectedoblique position vertical to the long axis. Statistical analysis: The result ofexperiment was statistically analyzed with software SPSS17.0All data wereexpressed by M±SD, analyzed by Student`s,P<0.05, indicated statisticalsignificance. Results:1. There were no statistically significant in skeletalmorphology of TMJ among the patients in gender differences of twogroups(P>0.05).2. There were statistical differences in condylar longitudinaldistances,the gradient of articular tubercle,the vertical height the articulartubercle,height of glenoid fossa in the scissors-bite side of the experimentalgroup compared with those in the non-scissors-bite side (P<0.01).Theside-to-side differences of the condylar morphology,the glenoid fossamorphology,the position of condyle in the glenoid fossa were not statistically significant(P>0.05).3.There was statistically significant (P<0.01)in thevertical height the articular tubercle, height and width of glenoid fossa and thevalue of long axis of condyle of the control group compared with those inscissors-bite side of the experimental group. There was statistically significant(P<0.01)in the width of glenoid fossa and the value of long axis of condyle ofthe control group compared with those in non-scissors-bite side of theexperimental group.4.Significant differences were found in the height of thecondylar processus, the value of long axis of condyle(P<0.05)it wasstatistically significant (P<0.01)in the condylar longitudinal distances in thescissors-bite side of the experimental group in different developmental stages ofTMJ, and it was statistically significant (P<0.01)in height of glenoid fossa inthe non-scissors-bite side. Conclusion:1There was side-to-side difference inthe morphology of condyle and glenoid fossa of the patients with unilateralposterior scissors bite.2Age can contribute to the morphogenesis of theTMJ in the patients with unilateral posterior scissors bite on the adaptiveremodeling.3.No effect of gender on the skeletal morphology of the joint.It wassuggested to relieve posterior scissors bite as early as possible. |
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