ABSTRACT
OBJECTIVE@#This study aimed to investigate the therapeutic effects and advantages of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique.@*METHODS@#Ninety-seven patients who received treatment for skeletal class Ⅲ malocclusion at the Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2012 to January 2017 were selected for this retrospective study. All these patients refused surgery. They were divided into two groups in accordance with the type of skeletal malocclusion: mild-to-moderate skeletal malocclusion group (-4°≤ANB <0°) and severe skeletal malocclusion group (-8°≤ANB<-4°). Each of the two groups was divided further into two small groups in accordance with the technique used: T group (transmission straight wire technique) and M group (MBT technique).@*RESULTS@#The crossbite of all 59 patients in the mild-to-moderate skeletal malocclusion group was successfully treated. The molars were classified as classⅠrelationship, and the facial profile improved. Significant differences were found in the values of U1/SN angle, L1/MP angle, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05). In the severe skeletal malocclusion group, the crossbite of all 38 patients was cured or partially cured. Fourteen patients showed severe lower anterior teeth inclination (five in the T group and nine in the M group), and the profiles did not significantly improve. Significant differences were observed in the values of U1-NA value, U1/SN angle, L1-NB value, L1/MP angle, LLP, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05).@*CONCLUSIONS@#Relative to the MBT technique, the transmission straight wire technique has great advantages in improving facial profile, reducing the compensatory inclination of the upper and lower anterior teeth, and reducing the risk of root resorption in the treatment of skeletal class Ⅲ malocclusion.
Subject(s)
Humans , Cephalometry , Malocclusion , Malocclusion, Angle Class II , Malocclusion, Angle Class III , Maxilla , Retrospective StudiesABSTRACT
BACKGROUND:With the development of modern orthodontics, to invent an efficient appliance is the focus in recent studies. Transmission straight wire appliance was born on this background. This appliance can accelerate occlusion and shorten treatment duration. The relationship between distal width and angulation of gable bends of main arch wire needs to study in depth. OBJECTIVE:To establish three-dimensional finite element model of transmission straight wire appliance with better biological and mechanical similarity, and to obtain the relationship between distal width and angulation of gable bend of main arch wire. METHODS:By using scanning of spiral CT with 64 rows, the sectional image data in DICOM format of maxil ary dentition and maxil ae of the volunteers (Class Ⅱ, division 1) were obtained. With the help of Ansys workbench 13.0, Mimics 10.01, Unigraphics NX and Geomagic Studio 8.0 softwares, the three-dimensional finite element model including transmission straight wire appliance, bend, Australian Orthodontic Wire, maxil ae, maxil ary tooth and periodontal ligament was established in Windows XP Service Pack 3 system. RESULTS AND CONCLUSION:A three-dimensional finite element model of transmission straight wire appliance was established, which consisted of 250 929 elements and 657 766 nodes. Furthermore, three-dimensional finite element model had higher geometric similarity and mechanical similarity, as wel as the advantages of adding or subtracting components according to the requirement of the research. The model was conductive to analyze the mechanical system of transmission straight wire appliance and guide the clinical application and appliance modification.
ABSTRACT
Objective To observe the clinical effects of transmission straight wire appliance on the treatment of AngleⅡ1 malocclusion and explore its mechanism.Methods Thirteen AngleⅡ1 malocclusion patients (6 males and 7 females) were treated with the appliance by extracting 4 first premolars or 2 first maxillary premolars.The results of cephalometric measurements before and after treatment were statistically analyzed.Results The average treatment time of 13 cases was 15.6 months.The overbite's treatment cost 4.2 months averagely.Overbite,overjet and molar relationship were turned to normal (only one adult case had complete distal in the molar relationship by extracting 2 first maxillary premolar) and lateral appearances were improved after treatment.The results of cephalometric analysis showed that the changes of SNB,ANB,U1-NA angle,L1-NB angle,U1-LI angle,U1-NA length,L1-NB length,L6-MP length,L1C-MP length,overbite,and overjet were of high statistical significance (P0.05).Conclusion Transmission straight wire appliance can quickly and efficiently correct AngleⅡ1 malocclusion.