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Objective@#To investigate the effect of corticotomy-facilitated orthodontics on the treatment time and final outcome in skeletal class Ⅱ division 1 patients.@*Methods@#Twenty adult skeletal class Ⅱ division 1 patients treated with two maxillary first premolar extractions were included and randomly divided into two groups (the corticotomy group and the control group). The treatment time was recorded and the changes of soft and hard tissue were compared by using three-dimensional measurement and analysis of cone-beam CT images before and after treatment.@*Results@#There was no significant difference in the alignment time between two groups, while the time of maxillary space closure and the total treatment time in corticotomy group ([5.8±1.3] and [24.9±5.1] months, respectively) were shorter than that in the control group ([9.9±1.1] and [30.8±4.6] months, respectively) and the differences were significant (P<0.01). In the corticotomy group, the retraction amount of the upper central in cisal margin, apical tip, supradentale, labrale superius and the increase of nasolabial angle were greater than those in the control group (P<0.05).@*Conclusions@#In patients with mild to moderate skeletal class Ⅱ division 1 malocclusion, corticotomy-facilitated orthodontics can not only shorten the treatment time, but is more conductive to the retraction of upper anterior teeth and improvement of the profile.
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Objective@#To investgate the effect of Herbst appliance on the growth and remodeling of the temporomandibular joint (TMJ) in class Ⅱ patients with mandibular retrusion by using MRI.@*Methods@#Between December 2010 and October 2014, 12 class Ⅱ patients (11-16 years old) with mandibular retrusion were chosen. The patients were divided into two groups. The control group included 7 patients (14 joints) with normal disc condyle relationship and the anterior disc displacement (ADD) group included 5 patients (10 joints) with anterior disc displacement. The MRI images of TMJ were measured, including condylar height, joint space index and disc position ratio, before and after the treatment.@*Results@#The condylar height of the patients in the control group was significantly increased (P<0.001) after treatment, and no significant difference in joint space index (P=0.821) and disc position ratio (P=0.146) was found. The joint space index of the patients ([-14.70±8.82]% and [4.90±11.35]%) in ADD group changed significantly (P<0.001) after treatment, and no significant difference in condylar height (P=0.294) and disc position ratio (P=0.120) was found.@*Conclusions@#The normal disc condyle relationship was beneficial to the reconstruction of the condylar process, and the increase of the condylar height. The condyle moved forward in patients with anterior disc displacement after treatment.
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Mandibular hypoplasia is very common clinically. Studies have reported that temporomandibular joint internal derangement (TMJID) might manifest as mandibular retrusion, and whether there is a direct correlation between them remains controversial in academia. On the other hand, for adolescent patients with skeletal class Ⅱ malocclusion, the growth of mandible could be motivated by orthopedic force, and then the mandibular retrusion corrected. However, if TMJID is the direct cause of mandibular retrusion, orthopedic treatment will not have a significant effect on it. Base on literature review and analysis as well as our own research, this article will review the distribution of structural abnormalities of the temporomandibular joint in adolescents with mandibular hypoplasia and its association with skeletal class Ⅱ malocclusion, as well as the effect of TMJID on the treatment of skeletal class Ⅱ malocclusion in adolescents.
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Objective:To study crown-root morphology of maxillary anterior teeth in ClassⅡ,division 2 malocclusion using cone-beam CT (CBCT)combined with computer aided measurement technology to provide guidance for clinical treatment.Methods:The samples which consisted of 36 cases radiographed with CBCT techniques were selected and divided into two groups (1 8 each )based on the type of maloc-clusion presented:ClassⅡ,division 2 group (groupⅡ2)and ClassⅠgroup (groupⅠ).The measure-ments of crown-root morphology including crown-root angle and surface-shaft angle were got by Multiple Planer Reconstruction of CBCT data uploaded into InvivoDental software 5.0.The data were processed with SPSS 20.0 software package and t test was employed for comparison of angular measurements. Results:In group Ⅰ,crown-root angles of maxillary central incisor,maxillary lateral incisor and maxillary canines were 1 79.08°±3.31 °,1 76.55°±2.77°and 1 84.20°±2.51 °respectively, surface-shaft angles were 21 .00°±2.63°,1 9.63°±2.35°and 1 9.36°±2.30°respectively. While in group Ⅱ 2 ,crown-root angles of maxillary central incisor,maxillary lateral incisor and maxillary canines were 1 76.80°±2.62°,1 74.1 3°±3.28°and 1 81 .79°±2.88°respectively, surface-shaft angles were 23.20°±2.95°,22.29°±2.1 9°and 20.61 °±2.34°respectively. Compared with group Ⅰ,significant statistical differences were observed with the exception of sur-face-shaft angle of maxillary incisor.There was significant difference in crown-root angle between group Ⅱ2 and 1 80 °.Conclusion:The maxillary anterior teeth in ClassⅡ,division 2 malocclusion exhibited significant crown-root morphology which would influence the torque after orthodontic treat-ment.Special attention should be paid to the position of maxillary anterior teeth roots during ortho-dontic treatment for Class Ⅱ,division 2 malocclusion.The ideal position of tooth movement should be decided by the root rather than the location of the crowns.
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Objective To investigate changes in craniomaxillofacial soft and hard tissues following orthodontic treatment by MBT edgewise technique with fix appliance in patients with Angle classⅡdivisionⅠmalocclusion. Methods Fifty patients with Angle classⅡdivisionⅠmalocclusion were selected in this study. All patients were treated with MBT edgewise technique. Cephalometrics tracings were performed before treatment and after treatment. Cephalometrics measurements were statistically analysed by t-test. Results After the orthodontic treatment, the main changes were the reduction of maxillary and mandibular prominence and the increasement of the Pg′B′-FH and Pog-Pog′and upper-lower prominence as well. The appearance of uncovered teeth by their lips was obviously improved. The changes of soft issue profile are the increment of nasolabial angle and the changes among UL-U1, LL-L1 and the E-line. Conclusion Patients with Angle classⅡdivisionⅠmalocclusion have normal overjet and overbite, and also have a better appearance of soft tissue after the extraction treatment.
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Objective To investigate the clinic application of micro-implant anchorage in the treatment of maxil-lary protrusion malocclusion. Methods Twenty-two patients,aged 18 to 25 years old,with maxillary protrusion were divid-ed into two groups:experimental group and control group with 11 patients in each group. All patients were treated with ex-traction. Micro-screw palatal implant was used in the cases of experimental group as orthodontic anchorage ,and traditional anchorage composed of extraoral arch used in the cases of control. The cephalometric films were measured before and after treatment. Statistical methods were utilized to analyze the morphological changes of facial profile and hard tissues in both groups. Results The values of U1-NA(mm:3.08±1.18 vs 8.15±3.05) and U1-SN(101.90°±3.50° vs 117.90°±6.05°) were sig-nificantly decreased after treatment compared with those before treatment in the experimental group ( P<0.01). The value of U1-L1(123.98°±5.78°vs 103.89°±8.95°) was significantly increased after treatment (P<0.01). In control group, the values of U1-NA (mm:5.01±1.34 vs 9.12±2.13) and U1-SN(101.90°±3.97° vs 114.87°±7.69°)were significantly decreased after treat-ment. The values of U1-L1(126.01°±3.12°vs 112.98°±5.98°) and U6-PtPNS(mm:21.45±2.43 vs 18.36±2.19)were significant-ly increased after treatment (P<0.05). The value of U1-L1(19.48°±8.90° vs 13.01°±5.90°) was significantly changed in exper-imental group than that of control group, but the value of U6-PtPNS(mm:0.90±0.29 vs 3.78±0.12)was significantly changed in control than that of experimental group (P<0.01). Conclusion The maxillary protrusion malocclusion with micro-im-plant anchorage can be used as treatment for patients with maxillary protrusion that needs strong anchorage.
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Objective:Cluster and discriminant analysis of the morphological characters of Angle's Class Ⅱ malocclusion was performed using Procrusts standardization.The classification of craniofacial morphology with the help of morphometry and multivariate statistics was also discussed.Methods: A total of 894 class Ⅱ patients were collected from the orthodontic department,Peking University School and Hospital of Stomatology during 1997-2000.Using Procrusts standardization and cluster analysis,the samples were divided into different groups,discrimination equations were then established.Results: The samples were divided into 11 subdivisions by Procrusts superimposition and cluster analysis.Three discrimination equations were established.The accuracy rate of cross-validated grouped cases was 80.17%.Conclusion: Procrusts standardization had certain advantages in morphological classification;cluster analysis could be used in classification of Angle class Ⅱ malocclusion;For different types,the differentiate rate was not the same;the discrimination equations was the foundation for future research.