Study Of The Condylar Movement Traces Of The Unilateral Posterior Buccal Crossbite

The study of condylar movement trace is one important part of the mandibular function analysis, it has important reference value for the diagnosis,analysis and effect judgment of the normal occlusion,various malocclusion and temporomandibular disease. It can offer certain reference for orthodontic clinical functional analysis and treatment effect evaluating with handicapping dentofacial anomaly to analyze the condylar movement trace characteristic of various malocclusion.Through the studying for condylar movement trace of common malocclusion in the past, we found that different malocclusion usually has correspondingly different condylar trace characteristic. In consideration of the critical changing about occlusion rebuilding during the therapy course for the patients with unilateral posterior buccal crossbite, it is very important for choosing suitable therapy time and protecting temporomandibular function to understand the condylar trace characteristic about these patients.Therefore, the purpose of this study is to investigate the condylar traces characteristic of the patients with unilateral posterior buccal crossbite during various mandibular movement and to compare the difference with the individual normal occlusion. Twenty-six subjects with the normal occlusion and 26 subjects with the unilateral posterior buccal crossbite were tested by CADIAX for the condylar movement. The open/close, protrusion/retrusion and lateral excursion traces were recorded.The data were analyzed using SPSS 10.0 software package, group t-test, paired t-test or rank sum test were used to compare the difference between the two groups and inside the control or experimental group. The conclusions were as follow: the condylar traces of the control group subjects were symmetrical, regular, smooth, fluent and the bilateral condylar shift and inclination have no statistical difference. The condylar traces of the experiment subjects were zigzag, inconsistent , asymmetrical and the side shift of the condyle is increased. During the open/close movement, the buccal crossbite side condylar traces in the direction of the sagittal,space shift and the sagittal condylar inclination in the max-mm, 5mm shift were smaller than the control group′s(P<0.05), the bilateral the transversal condylar inclination of the experiment subjects in the max-mm, 5mm shift were larger than the control group′s(P<0.05). During the protrusion/retrusion movement, the buccal crossbite side are smaller than the non-buccal crossbite side in the direction of the sagittal,space shift(P<0.05). The sagittal condylar inclination of the buccal crossbite side are smaller than the non-buccal crossbite side as well as the normal subjects(P<0.05).About the transversal condylar inclination, the reverse crossbite side of the experiment subjects are larger than the normal subjects in the 5mm condyle shift(P<0.05). During the lateral excursion movement, being the non-working side condylar,the sagittal, vertical and space shift of the non-buccal crossbite side were larger than the buccal crossbite side and the normal subjects, but the horizontal shift was smaller(P<0.05). The sagittal condylar inclination of the non-buccal crossbite side were larger than the buccal crossbite side and the normal subjects, but the transversal condylar inclination was smaller(P<0.05).In sum, the condylar movement traces of the patients with unilateral posterior buccal crossbite have some individual difference, and also have certain typical characteristics. It mainly manifests that the condylar traces are zigzag, inconsistent , the condylar movement abilitity is limited, the bilateral movement is asymmetrical and the side shift is increased. It is necessary to correct the buccal crossbite relationship early in order to protect the normal temporomandibular movement function. At the same time, the obtaining firstly of condylar movement trace characteristics about unilateral posterior buccal crossbite not only supplies the orthodontic clinical functional examination requirement, but also gives certain beneficial reference for another stomatology study such as prosthetics, dental-occlusion.