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Objective • Using cone-beam computed tomography (CBCT) to compare alveolar bone changes in maxillary anterior area secondary to maxillary incisor retraction adjunct with tip (R&Tp) and retraction adjunct with torque (R&Tq) movements. Methods • Forty teenagers with Angle's class Ⅱ division 1 malocclusion who had completed orthodontic treatment met the inclusion criteria and were selected, and all of their 160 maxillary incisors were classified into two categories, namely R&Tp group and R&Tq group, according to their actual retraction pattern. Pre- and post-treatment CBCT images and 3D measurement software were used to measure and analyze tooth retraction and alveolar bone height and thickness changes within each group and to compare treatment changes of teeth and alveolar bone between two groups. Results • Anterior teeth in each group were intensively retracted and uprighted, with a longer retraction distance of incisal edge and a greater retraction angle of teeth in R&Tp group than in R&Tq group (both P=0.000). Alveolar bone thickness was significantly decreased at L3 and P1 in R&Tp group (both P<0.05), while it was significantly decreased at P1 and P2 in R&Tq group (both P<0.05). Total alveolar bone thickness decreased at T1 in R&Tp group (P=0.000) and at all levels in R&Tq group (all P=0.000). Finally, alveolar ridge height in two groups dropped both in the buccal (both P=0.000) and palatal (both P=0.000) sides, with a more prominent extent in the palatal side, and ridge height dropped most in palatal side of the teeth in R&Tq group. Conclusion • The buccal root apex area and the palatal alveolar ridge area of alveolar bone in the R&Tp group and the cervical and middle area of incisor root in palatal side of alveolar bone in the R&Tq group are high-risk areas for alveolar bone resorption when anterior teeth in teenagers with Angle's class Ⅱ division 1 malocclusion are intended to have en masse retraction.
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Objective:To explore the changes of orthodontic therapy with tooth extraction on frontal view of facial soft tissue in adult females with Class Ⅱ division 1 malocclusion.Methods:Frontal view of facial soft tissue aesthetic charaeteristics of 30 with and 21 without tooth extraction adult females with Class Ⅱ division 1 malocclusion were measured with direct anthropometry before and after orthodontic treatment.Results:After the extraction treatment,the distance of N-Me,Sn-Me,Sn-UL,LL-Sm,Sto-Me,Ch-Ch in-creased(P 0.05).There was no sig-nificant change in each parameter in nonextraction group(P >0.05).Between the 2 groups Sn-UL,LL-Sm and UL-LL showed differ-ence(P 0.05).Conclusion:Orthodontic treatment with tooth for the fe-males with Class Ⅱ division 1 malocclusion can improve the incompetent lips,and recover the coordination between the upper and lower lips.There is little change on facial height and width.
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The effect of extraction and nonextraction treatment on the soft tissue profile of the subjects borderline Angle classⅡ division 1 malocclusion is concerned mainly by orthodontists.This article reviewes the effect of extraction and nonextraction treatment on the soft tissue profile of the subjects with Angle classⅡ division 1 borderline patients and the important factors(such as differences between the types of tooth extraction and growth).The aim is to guide clinic diagnosis and treatment for borderline Angle classⅡ division 1 malocclusion.
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Objective; To evaluate the efficacy of Twin-block appliance in Class Ⅱ division 1 of adolescents. Methods: Several e-lectronic databases (PubMed, The Cochrane library, Embase, CBMdisk, CNKI, VIP)were searched. Abstract that appears to fulfill the initial selection criteria were selected by consensus and original articles were retrieved. Five Chinese journals were hand searched for possible missing articles. Randomized controlled trials(RCTs) that evaluate the efficacy of Twin-block appliance in Class Ⅱ division I adolescents without any surgical intervention or syndromic characteristics were considered. A comparable untreated control group was required to factor out normal growth changes. The quality of included studies was evaluated according to Cochrane Reviewers Handbook 4.2.6 Meta-analysis was performed by using RevMan 5.0.0 software. Results: Four RCTs including 289 patients were identified. The results of our meta-analysis showed a significant increase on SNB angle, Ar-Gn, Nasolabial angle and Labial-mental fold compared with control group(P<0.05). Whereas overjet, overbite, ANB angle and Ls-E had a significant decrease. In addition, SNA angle and Li-E didnt show statistical significant changes(P>0. 05). Conclusion; In Class II division 1 of adolescents, Twin-block appliance can effectively decrease their overjet, overbite, ANB angle, and induce anterior-posterior growth of mandible. The effect on restrain forward growth of the maxilla was unclear. More RCTs are required to evaluate the efficacy of Twin-block appliance.
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Objective:To evaluate the occlusal function of patients with Class ⅡDivision 1 malocclusion.Methods:T-Scan II system 4.02 was used to record total occlusal force(TOF),asymmetry index of occlusal force(AOF),number of occlusal contacts(NOC),asymmetry index of occlusal area(AOA),center of force(COF),maximal movement of COF(MMCOF),occlusal interference index(OII)of 26 Class ⅡDivision 1 malocclusion in the intercuspal position(ICP)comparing with 26 normal occlusion.Results:TOF in Class ⅡDivision 1 malocclusion was significantly smaller than that in normal occlusion(P0.05);AOF,AOA,COF,MMCOF,OII in ClassⅡ1 were significantly higher than those in normal occlusion(P
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Objective:To investigate the relationship between the structure of TMJ and the craniofacial pattern,occlusion in ClassⅡ1mandibular retrusion children. Methods:TMJ MRI,lateral cephalometric were taken respectively from 30 ClassⅡ1 patients (14 boys and 16 girls,the average age was 10.8?1.1 years). The condyle position and disc position were measured. The correlation of condyle and disc position with craniofacial pattern and occlusion were analyzed metrically and compared with pearson test.Results:There were low positive correlation between MP-SN angle and anterial space. No correlation between posterior-anterior ratio and other data were found. The posterior facial height and Dp-Cc/Cs-Cc angle had low positive correlation. The anterior facial height and Dp-Cc/Cs-Cc、Ca-Ca'、Ca-Cp showed low negative correlation,and little correlation was found between condyle position and overbite and overjet. Overbite had no correlation with disc-condyle-fossa relationship. However,The positive correlation was found between the overjet. and Ca-Dm and Dp-Cc/Cs-Cc,and Pearson coefficient is 0.420 and 0.460.Conclusion:Vertical craniofacial patter has relation to forward displacement of condyle and backward displacement of disc. A deeper overjet is related with a higher risk of abnormal disc-condyle-fossa relationship.
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Objective:To clarify the treatment effects of T4K on Class II division 1 malocclusion.Methods:Twenty patients (10 girls and 10 boys) aged 8~10 years old with Class II division 1 malocclusion were treated with T4K appliance(Myofunctional Research Co., Queensland, Australia).A control group of 20 patients aged 9~11 years old with untreated Class II division 1 malocclusions was used to eliminate the possible growth effects. Lateral cephalograms were taken before and after treatment. Final cephalograms were taken (12.1?1.8) months after T4K application.The subjects in control group were observed for (11.2?2.1) months.The mean and standard deviations for cephalometric measurements were analyzed by paired-samples and independent-sample t-tests. Results:In the treated subjects significant changes including anterior rotation and sagittal growth of the mandible, increased SNB and facial height, reduced ANB, increased lower incisor proclination, upper incisor overjet reduction were observed.Conclusion:T4K appliance is effective in the treatment of class II division 1 malocclusion.