OBJECTIVETo evaluate the shape and structure of different separators affecting the mechanical behavior.

METHODSThe stress of different separators was analyzed by ANSYS software. Various separators were meshed into one-dimensional solid elements and the material character parameters were inputted. The loads were added gradually.

RESULTSThe stress was related to the arm of force and the point of force application.

CONCLUSIONSThe force applied can be controlled by selecting different separators.

Finite Element Analysis ; Humans ; Orthodontics, Corrective ; instrumentation ; Stress, Mechanical

OBJECTIVEObserve the clinical effect of removable lingual arch plus auxiliary spring for convenient dental (especially mandibular) arch expansion.

METHODSSeventeen patients with dental arch constriction complicated by mild dental crowding were enrolled in this study, including 9 requiring maxillary arch expansion and 8 necessitating mandibular expansion. The patients were divided to two groups at random for arch expansion with removable lingual arch plus auxiliary spring and with Quad-helix, respectively, and the effect of arch expansion was compared between the two groups.

RESULTSAfter 8 weeks of arch expansion, the average width of U4-U4 and U5-U5 in removable lingual arch group was enlarged by 2.2 mm and 3.0 mm, and that in Quad-helix group by 2.3 mm and 3.5 mm, respectively, showing no significant differences between the two groups (P>0.05). After 12 weeks of treatment, the average width of L4-L4 and L5-L5 in the former group was enlarged by 2.3 mm and 2.5 mm, respectively, significantly greater than that in the latter group (1.0 mm and 1.2 mm, P<0.05).

CONCLUSIONRemovable lingual arch plus auxiliary spring allows significant expansion of the middle segment of the dental arch (bicuspids), and can be more effective than Quad-helix for mandibular arch expansion.

Adolescent ; Child ; Dental Arch ; pathology ; Humans ; Malocclusion ; therapy ; Orthodontic Appliances, Removable ; Orthodontics, Corrective ; methods ; Palatal Expansion Technique ; instrumentation ; Young Adult

OBJECTIVEThe skeletal Class III malocclusion often occurs in ethnic Asia population, and it is difficult to obtain an ideal results if only treated with protraction headgear (PH). However, the combined rapid palatal expansion (RPE), Edgewise Technique and PH can reach it, so the authors investigated the methods and characteristics of combined RPE, Edgewise Technique and PH in the treatment of skeletal Class III malocclusion.

METHODSFifteen patients, aged 8.5-12 years, including six males and 9 females, with skeletal Class III malocclusion and maxillary retrusion were selected for this study. Radiographs of left hand and wrist showed that all patients were at the pre-pubertal stage. The duration of treatment was nine months on average.

RESULTSThe SNA and A-ptm increased with a mean of cephalometric analysis, which showed significant difference (P < 0.05).

CONCLUSIONObvious skeletal and profile changes can be achieved with combined RPE, Edgewise Technique and PH in the treatment of early skeletal Class III malocclusion.

Child ; Extraoral Traction Appliances ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Orthodontics, Corrective ; instrumentation ; methods ; Palatal Expansion Technique

OBJECTIVE: To evaluate the therapeutic effects of MBT straight wire on extraction case of Class II division I. METHODS: Thirty-six class II division I malocclusion patients were treated with MBT straight wire by extracting 4 bicuspid premolars or 2 maxillary bicuspid premolars. The X-ray cephalograms were analyzed before and after the treatment of MBT straight wire. RESULTS: After the treatment, the overjet was reduced by 6.04 mm (P < 0.01); U1-NA was reduced by 15.43 degrees (P <0.01); and U1-NA (mm) was reduced by 4.71 mm (P <0.01). ANB was significantly reduced (P < 0.05). CONCLUSION MBT straight wire not only shortens the operation but also shows superior effect for Class II division I malocclusion cases.
Adolescent ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; therapy ; Orthodontic Appliance Design ; Orthodontic Wires ; Orthodontics, Corrective ; instrumentation ; methods

Child ; Dental Implantation, Endosseous ; Extraoral Traction Appliances ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Maxilla ; abnormalities ; Orthodontic Anchorage Procedures ; instrumentation ; Orthodontic Appliance Design ; Orthodontics, Corrective ; instrumentation

OBJECTIVETo compare the difference between J-hook and micro-implant anchorage in the treatment of patient with bimaxillary protrusion.

METHODSThirty patients with bimaxillary protrusion were divided into two groups (J-hook and micro-implant groups) and treated with MBT appliance. Four first premolars were extracted in all patients. Cephalometric analyses were carried out before and after treatment.

RESULTSIn J-hook group and micro-implant group,computerized cephalometric analysis revealed that before treatment U6C-PP was (12.4 +/- 0.2) mm and (12.5 +/- 0.1) mm, respectively,and after treatment U6C-PP was (12.6 +/- 0.1) mm and (12.8 +/- 0.1) mm,respectively. The difference between J-hook group and microimplant group was significant (P < 0.01). The other differences of cephalometric analyses between J-hook group and micro-implant group was not significant.

CONCLUSIONSBoth J-hook and micro-implant could provide adequate anchorage in the treatment of patients with bimaxillary protrusion.

Adolescent ; Adult ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class I ; therapy ; Orthodontic Anchorage Procedures ; instrumentation ; Orthodontic Appliances ; Orthodontics, Corrective ; instrumentation ; methods ; Young Adult

Occlusal-maxillo-facial structural change of crossbite malocclusion after orthodontic therapy by modified ACTIVATOR appliance was investigated. Eighty crossbite cases of deciduous dentition and mixed dentition were treated by modified ACTIVATOR. Through pre- and post-treatment analysis of stone model, Schuller's position X-ray and craniofaciometrics, the change in craniofacial length, width and height in early-phase crossbite malocclusion was studied. The results showed that there was no significant change in the width of maxillary and mandibular dental arch. Maxillary length and protrusion was increased significantly, upper incisors slopped labially. The lower incisors slopped lingually, mental angle decreased more severely. The lower and posterior facial height was increased to normal level.
Cephalometry ; Child ; Child, Preschool ; Dental Arch ; anatomy & histology ; Dental Stress Analysis ; Dentition, Mixed ; Female ; Humans ; Male ; Malocclusion ; therapy ; Maxilla ; anatomy & histology ; growth & development ; Orthodontic Appliances, Removable ; Orthodontics, Corrective ; instrumentation ; Orthodontics, Interceptive ; instrumentation ; Tooth, Deciduous

Occlusal-maxillo-facial structural change of crossbite malocclusion after orthodontic therapy by modified ACTIVATOR appliance was investigated. Eighty crossbite cases of deciduous dentition and mixed dentition were treated by modified ACTIVATOR. Through pre- and post-treatment analysis of stone model, Schuller's position X-ray and craniofaciometrics, the change in craniofacial length, width and height in early-phase crossbite malocclusion was studied. The results showed that there was no significant change in the width of maxillary and mandibular dental arch. Maxillary length and protrusion was increased significantly, upper incisors slopped labially. The lower incisors slopped lingually, mental angle decreased more severely. The lower and posterior facial height was increased to normal level.
Cephalometry ; Dental Arch/anatomy & histology ; Dental Stress Analysis ; Dentition, Mixed ; Malocclusion/*therapy ; Maxilla/*anatomy & histology ; Maxilla/growth & development ; *Orthodontic Appliances, Removable ; Orthodontics, Corrective/*instrumentation ; Orthodontics, Interceptive/instrumentation ; Tooth, Deciduous

This study is designed to theoretically evaluate the treatment effects of MEAW with tip back bends on the mandible dentition when used as a finishing archwire without elastic and with long class III elastics respectively, and to compare them with those of stainless-steel wire and shape-memory wire. The finite element analysis (FEA) method was adopted and the findings were as follows: (1) In the case of no elastics, the MEAW rotates the second premolar, the first molar and the second molar distally while rotating other teeth mesially, and depresses anterior teeth. However, the stainless-steel wire and the shape-memory wire rotate molars distally while rotating other teeth mesially. Furthermore, they extrude anterior teeth and depress posterior teeth. (2) The MEAW with tip back bends and long class III elastics inclines and rotates posterior teeth more distally than the MEAW with only tip back bends does. In the case of tip back bends and long class III elastics loaded together, the shape-memory wire inclines teeth in greater strength as compared with the stainless-steel wire. (3) The stress level of tooth root is the lowest with MEAW, the highest with stainless-steel wire, and is middle with the shape-memory wire. From these results, it is suggested that: (1) The MEAW therapy technique is effective for leveling the curve of Spee and regulating tooth respectively. (2) The MEAW therapy technique can transfer therapy force efficiently. (3) The MEAW is considered to be suitable for treating openbite malocclusion to make the posterior teeth upright because it effectively rotates teeth distally through the force of posterior bends and long class III elastics. (4) The loaded force on the teeth is more soft and permanent in the MEAW than in the stainless-steel wire and the shape-memory wire.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Malocclusion ; therapy ; Orthodontic Appliance Design ; Orthodontic Brackets ; Orthodontic Wires ; Orthodontics, Corrective ; methods ; Tooth Movement Techniques ; instrumentation

OBJECTIVETo evaluate the effects of magnetic Twin-block appliance in the treatment of skeletal class II cases.

METHODSThe magnetic Twin-block appliance was embedded with two pairs of neodymium-iron-boron (Nd(2)Fe(14)B) rare earth permanent magnets in the upper and lower inclined planes of Twin-block appliance. The sample comprised of 13 skeletal class II patients in the late mixed or early permanent dentition treated by magnetic Twin-block appliance. Cephalometric films were taken before and after treatment. Helix CT images of the temporomandibular joint (TMJ) in all patients were examined before treatment (T1), during treatment (4 months after appliance placement, T2), after treatment (T3) and one year after treatment (T4).

RESULTSA double contour image was detected in the superior posterior part of the condylar head on the pseudo-sagittal reconstruction plane pictures of T2 in 11 patients. The double contour image could be observed in most patients as well. This image also exhibited on the pictures of T3 in several patients. On the pictures of T2 and T3 in some patients, interruption of cortical bone and "bifurcation phenomenon" of condyles were shown. Pictures of T1 and T4 were similar and no signs of remodeling of TMJ were observed. Cephalometric analysis revealed significant changes in the maxillofacial structure after treatment. The profile of patients improved.

CONCLUSIONSBone remodeling of condyle occurred during the magnetic Twin-block treatment in class II patients. Magnetic Twin-block appliance was effective in the treatment of the growing skeletal class II patients.

Adolescent ; Bone Remodeling ; Child ; Female ; Humans ; Magnetics ; Male ; Malocclusion, Angle Class II ; physiopathology ; therapy ; Mandibular Condyle ; physiopathology ; Orthodontic Appliances ; Orthodontics, Corrective ; instrumentation ; Treatment Outcome