Objective: To evaluate the effect of a new method to treat early primary crossbite . Methods: 20 cases (2.8～6.5 years old ) with anterior crossbite were treated by bonding appliance combined with protracting mask. Cephalometric radiographs were taken and analyzed before and after treatment. Results: On average,in all the 20 cases the maxilla were moved 2.06 mm forward ,mandibular were turned 2.45?downward and backward ,the anterior crossbite was corrected and the face profile was improved satisfactorily.The treatment was conducted for 1.7 months on average. Conclusion: Using bonding appliance combined with protracting mask to treat early primary crossbite can achieve good effects for young children .

0.05). Conclusion: The measurements of molar distal movement on model are smilar to those on cephalometric radiograph.

objective: To evaluate the effect of Quad Helix appliance in expanding narrow dental arch. Methods: 12 cases were treated by Quad Helix appliance. The effect was evaluated by measurement of the dental arch. Results: The dental arch of all the patients was expanded in half a year.The width between the maxillary first molars increased by 8.95 mm, and the width between maxillary first premolars increased by 5.7 mm. The average time of expanding was 20.75 weeks, the expanding efficiency was 0.43 mm per week. Conclusion: Quad Helix is an effective orthodontic appliance for correction of narrow dental arch.

Objective:To evaluate the influence on root resorption after distalizing molars with face bow.Methods:15 cases whose molars were distalized with face bow were selected in present research. Root lengths were measured on pre-treatment and post-treatment dental films taken with the oral positioner. The distances of molar distalization were measured on cephalometric radiographs.The differences of the pre-treatment and post-treatment root lengths were evaluated by the Paired t-test.The correlation between the distance of molars distalization and the root resorption of the maxillary molars was analyzed with Pearson's correlation coefficients.Results:The root lengths between the pre-treatment and post-treatment showed a statistically significant difference(P

Objective:To investigate the indications of lower incisor extraction in orthodontic treatment of malocclusions. Methods:42 patients (males 16,females 26) were divided into four groups: abnormal Bolton index; class III malocclusions with anterior teeth cross bite; one congenital lower incisor losing; and anterior teeth area periodontal disease.One lower incisor extraction, one lower incisor and other teeth extraction and other accessorial therapy were used in the treatment. Results:According to these four different conditions, alternative treatment plans of lower incisor extraction should be determined. For the former two conditions, one lower incisor was extracted; A lower incisor and two maxillary first premolars were extracted in the third condition, in which lower canines and first premolars should be grinded to improve esthetics; In the last condition, some maxillary teeth need stripping besides extracting one lower incisor. All of the 42 cases achieved satisfactory results, normal overbite and overjet and stable occlusal relationship. Conclusion:To be well acquainted with the indications of the extraction of the lower incisor in orthodontic treatment of malocclusions can help to achieve satisfactory clinical effect.

Objective:To compare shear bond strength(SBS)of bonded and rebonded orthodontic brackets and influence of rebonded orthodontic brackets using different treatment methods on SBS.Methods:60 extracted premolars were evenly divided into three groups.Brackets were debonded with conventional techniques and then removed of residual adhesives from the base mesh using three different treatments.In groupⅠ,rebond a new bracket at the second,third bonding times.In group Ⅱ,remove residual adhesives from the base mesh with fire at the second,third times,then rebond the same bracket.In group Ⅲ,remove that using a tungsten carbide bur at the second,third times,then rebond the same bracket.Shear test was performed to compare the SBS and adhesive remnant indexes(ARI)among different groups.Results:The SBS of three groups at the first bonding sequence were(10.00?2.95)MPa,(9.57?2.45)MPa and(9.09?2.58)MPa.The SBS at the second,third debonding sequence in group I,group II,and group III were(9.55?2.84)MPa and(10.32?2.59)MPa,(7.30?2.15)MPa and(7.14?1.93)MPa,(12.13?2.93)MPa and(12.86?3.08)MPa,respectively.In group Ⅱ,the SBS was significantly lower,however,in group Ⅲ,the SBS was significantly higher,and the results showed significant differences(P

Objective:To study the effects of unilateral posterior crossbite on masticatory muscle functions pattern by using electromyography(EMG).Methods:20 subjects(11 males and 9 females)with unilateral posterior crossbite were selected.Subjects were instructed to stay mandibular postural position and to make maximum bite in intercuspal position(ICP)and bilateral chewing.EMG data of the left and right masseter and anterior temporalis muscles were recorded.Asymmetry index of masseter muscles(ASMM) and asymmetry index of temporalis muscles(ASTA)were calculated and compared.20 subjects with individual normal occlusion were used as control.Results:Compared to control group,masseter and temporal muscle activities in unilateral posterior crossbite group were lower in maximum bite and bilateral chewing;The activities of two muscles at crossbite side were lower than that at noncrossbite side.Under maximum bite and bilateral chewing,ASMM and ASTA in unilateral posterior crossbite group were significantly higher than those in control group;ASMM and ASTA in Subjects with one posterior tooth crossbite is lower than subjects with several teeth crossbite.Conclusion:It can be suggested that unilateral posterior crossbite may damage the function of mastication muscle.

Implant anchorage depressed the elongated opposed teeth to prepare enough space for the mandibular dentition.Finally,a better dental implant prosthesis can be achieved.

Objective:To study the technique of treatment of ma lo cclusion with congenital individual missing lower incisor . Method s: Ten cases of malocclusion(male 3, femal 7) with congenital missi ng lower incisor were selected. The casts and cephalograms of pretreatment and posttreatment were measured and analysed respectively. The malocclusions were corrected by changing the position of jaws and teeth. Stripping, extraction and so on were applied in the treatment for the achievement of normal overjet and ov erbite according to the Bolton index. Results: Intercusp al bite, normal overjet and overbite were achieved in the ten cases. The majorit y of lower anterior teeth were anteversion. The width between lower canines decr eased. Conclusion: Satisfactory occlusion can be achieve d by orthodontic treatment in the patients of malocclusion with congenital indiv idual lower incisor missing.

0.05) . Conclusion: Mini-implant can replace traditional anchorge composed of extraoral arch and Nance arch in the moving of cuspid distally.