Three-dimension Evaluate The Condyle Changes Of Adult Patients With Class â…¡ Division1 Malocclusion After Orthodontic Treatment In CBCT

ObjectiveCondyle as a part of the temporomandibular is one of the center of mandibular growth and development, its surface is covered with a layer of fibrocartilage with multidirectional proliferation. Condylar cartilage as a secondary cartilage still have the remodeling capacity after mandibular developed when it accepted functional stimulation. The pressure of articular cavity would change when the position of the condyle in the glenoid fossa is changed, it will the release biological signal and osteoblasts or osteoclasts will be activated, so that condylar morphology change in order to adapt to the new position.Class II Division I malocclusion deformity is refers to the upper and lower teeth, alveolar bone and jaw in the sagittal profile and often accompanied by perpendicular problems. In the domestic and foreign research on the pathological mechanism of the maxillary no obvious abnormality, mandibular hypoplasia resulting in mandible to the base of the skull and upper jaw relatively retrusion and molar distal relationship and anterior teeth overjet. Due to limitations of early imaging technology means, the research of condyle position and morphology changes of adult patients with Class Ⅱ division I malocclusion is relatively rare.Through to Class II division I malocclusion adult orthodontic patients before and after treatment of CBCT images to reconstruct the three-dimensional image, use computer software to registration 3D image and measure the condyle position and shape accurately from the three dimensional accurate. It will provide guidance for clinical orthodontic practice to accurately evaluate condyle position and morphological changes after orthodontic treatment.Methods and materialsIn this study, we selected the 2010-2015 period was completed in the Stomatology Hospital of Shandong University and orthodontic treatment of 34 adult patients with class II division I malocclusion.22 patients accept orthodontic treatment with premolar extraction, and 12 patients with extraction. The mean age of 34 patients from 19 to 34 years,24.6+3.7. Included sample standards:molar distal relationship; ANB angle more than 4°, the angle of the U1-LI less than 110°; complete dentition, no missing teeth, no history of arthritis,no temporomandibular joint disorder symptoms without opening and closing snapping, pain,no history of orthodontic treatment; no autoimmune disease history. After completion of therapy without internal and joint disorder symptoms.Respectively, all subjects before and after treatment of CBCT data in DICOM format files to be imported computer software and reconstruction 3D models. Data from pre and post-treatment respectively the anterior skull base and the front of the chin for stability of sign point STL registration. According to the measurement method of Kamelchuk:posterior space (PS), anterior space (AS), superior space (SS)^ width of glenoid fossa (WF)、 height of glenoid fossa (HF)、 the angle of articular eminence posterior slope (β). Schlueter and Hilgers measurement method measurement: anteroposterior diameter of condyle (CL1), mesial-lateral diameter of condyle (CL2), condylar height (CH) and angle of condyle anterior slope (y). Using SPSS software for data using a paired t test, P< 0.05 was statistically difference. According to the method of right and left lateral joint space before and after the clearance of the value evaluation of condylar articular fossa.Separate the pre-and post-treatment of mandibular CBCT data into STL file, divide condyle into 4 regions:Anterior-Medial (AM), Anterior-Lateral (AL),Posterior-Medial(PM) and Posterior-Lateral(PL) in three dimension images. The maximum diameter of the condyle in cross section were observed, the remodeling of condyle is divided into three categories:bone resorption, bone deposition and no changes. The condylar changes after orthodontics treatment were qualitatively analyzed. Chi square test was used for validation, P<0.05 there is a statistically significant difference.Result1. After orthodontic treatment the WC\WH and (3 had no significant difference (P> 0.05), both in extraction and non-extraction group patients. The AS of extraction group is reduced by 0.07mm after orthodontic treatment (P> 0.05), and non-extraction group decrease 0.03mm (P> 0.05), both two groups have no statistical significance. The PS increased 0.34mm in average (P< 0.05) after orthodontic treatment of extraction group, and non-extraction group increase 0.26 mm in average (P< 0.05), the change was statistically significance. The SS increased 0.47mm in average (P< 0.05) after orthodontic treatment of extraction group, and non-extraction group increase 0.54 mm in average (P< 0.05)., the change was statistically significance.2. After orthodontic treatment the W WF and (3 had no significant difference (P> 0.05), both in extraction and non-extraction groups. The CH increased 0.25mm in average (P< 0.05) after orthodontic treatment of extraction group, and non-extraction group increase 0.28 mm in average (P< 0.05)., the change was statistically significance. The y. increased 3.56°in average (P< 0.05) after orthodontic treatment of extraction group, and non-extraction group increase 3.11°in average (P< 0.05)., the change was statistically significance.。3. The position of condyle in glenoid fossa pre orthodontic treatment, there are 8 patients in anterior position,19 patients in median position and 7 patients in posterior position. After orthodontic treatment there are 17 patients in anterior position,14 patients in median position and 4 patients in posterior position. According to the chi square test P< 0.05, it has statistically difference.4. According to the compare CBCT data of pre and post orthodontic treatment, in the largest diameter of condyle:11 cases have bone deposition,32 cases with no change and 25 cases have bone absorption in anterior-lateral part (P< 0.05),it has significant difference; in anterior-mesial part,9 cases of bone deposition,29 cases of no change,30 cases of bone absorption (P< 0.05), it has significant difference; in posterior-lateral part,36 cases of bone deposition,24 cases of no change,8 cases of bone absorption (P< 0.05), it has significant difference; in anterior-lateral part, 33 cases of bone deposition,23 cases of no change,12 cases of bone absorption (P < 0.05), it has significant difference.Conclusion1. Adult patients with class II division I malocclusion after orthodontic treatment articular fossa without obvious change, condyle in the glenoid fossa position have forward under the trend of mobile.2. After orthodontic treatment in 34 patients with condylar head height average increase. The condyle anterior slope are inclined to bone resorption and posterior slope are inclined to the bone deposition3. The condylar position changes due to orthodontic treatment, the condyle will have corresponding alterations in order to adapt to the new position.