Cone-beam computed tomography study of root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology in high-angle Class Ⅱ open bite patients / 口腔疾病防治

Objective@#This study aimed to explore the root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology in patients with high-angle skeletal Class Ⅱ open bite, aiming to provide a reference for clinical treatment.@*. Methods@#This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. CBCT images of eighty-one untreated patients (40 anterior open bite patients and 41 normal overbite patients) with high-angle skeletal Class Ⅱ malocclusion were selected before treatment. Dolphin software was used to study the root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology, and the differences between the two groups were analyzed.@*Results@#There was no statistical significance in the root length of maxillary lateral incisor and canine between the open bite group and the normal overbite group, significant differences were found in the root length of maxillary central incisor （11.12 ± 1.37） mm、mandibular central incisor（10.15 ± 1.09）mm, mandibular lateral incisor（11.27 ± 1.15）mm and mandibular canine（12.81 ± 1.48）mm between the open bite group and the normal overbite group（P<0.05）. On the other hand, the two groups were significantly different in crown-root morphology of the maxillary central incisor (1.10° ± 3.62° vs. 4.53° ± 2.30°, P<0.01) but not in the mandibular central incisor.@*Conclusion@#The root length of the maxillary central incisor, mandibular central incisor, mandibular lateral incisor, mandibular canine in high-angle Class Ⅱ open bite patients is shorter than that in high-angle Class Ⅱ normal overbite patients, and the long axis of the crown of the maxillary central incisor in high-angle Class Ⅱ open bite patients obviously deviates toward the labial side relative to the long axis of the root. The crown-root angle is smaller, which is beneficial to torque control or adduction movement of the anterior teeth in high-angle Class Ⅱ open bite patients.

Meta-analysis of condylar changes produced by a Twin-block appliance in Class Ⅱ malocclusion / 华西口腔医学杂志

OBJECTIVES@#To evaluate the effects of a Twin-block appliance on the condyles of patients with ClassⅡmalocclusion by conducting a systematic review and a Meta-analysis.@*METHODS@#Pubmed, Embase, Cochrane Library, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and VIP Database were electronically searched. Randomized controlled trials, controlled clinical trials, and single-arm trials on condylar changes produced by a Twin-block appliance in patients with ClassⅡmalocclusion were included. Two reviewers independently extracted and assessed the risk of bias. Meta-analyses were conducted with Review Manager 5.3.@*RESULTS@#Eight studies were included; among which, seven were of high quality. After treatment with a twin block appliance, condyles moved anteriorly. The anterior joint spaces decreased (P<0.000 01), whereas the posterior spaces increased (P<0.000 01). The superior spaces were not changed (P=0.11). Moreover, a significant difference was observed in the increase of the condylar space index (P<0.000 01). After treatment, the anteroposterior diameters of the condyles and condylar height increased (P=0.000 2 and P<0.000 01, respectively). By contrast, no significant changes were discovered in the medial external diameters of the condyles (P=0.42).@*CONCLUSIONS@#A Twin-block appliance can promote the growth of a condyle in the posterior and upper direction and move it forward in favor of the correction of Class Ⅱ malocclusion.

Effect of maxillary expansion combined with orofacial myofunctional therapy on the position of the tongue of children with mouth breathing / 临床耳鼻咽喉头颈外科杂志

Objective:This study aimed to investigate the change of the position of the tongue before and after combined treatment of maxillary expansion and orofacial myofunctional therapy in children with mouth-breathing and skeletal class Ⅱmalocclusion. Methods:A total of 30 children with skeletal class Ⅱ malocclusion and unobstructed upper airway were selected. The 30 children were divided into mouth-breathing group（n=15） and nasal-breathing group（n=15） and CBCT was taken. The images were measured by Invivo5 software. The measurement results of the tongue position of the two groups were analyzed by independent samples t-test. 15 mouth-breathing children with skeletal class Ⅱ malocclusion were selected for maxillary expansion and orofacial myofunctional therapy. CBCT was taken before and after treatment, the measurements were analyzed by paired sample t test with SPSS 27.0 software package. Results:The measurement of the tongue position of the mouth-breathing and nasal-breathing groups were compared, the differences were statistically significant（P<0.05）. The measurement of the tongue position showed significant difference after the combined treatment of maxillary expansion and orofacial myofunctional therapy in children with mouth-breathing and skeletal class Ⅱmalocclusion（P<0.05）. Conclusion:Skeletal class Ⅱ malocclusion children with mouth-breathing have low tongue posture. The combined treatment of maxillary expansion and orofacial myofunctional therapy can change the position of the tongue.

Mandibular advancement with clear aligners and functional appliances in the treatment of skeletal ClassⅡmalocclusion: a systematic review and meta-analysis / 华西口腔医学杂志

OBJECTIVES@#This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group.@*METHODS@#PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis.@*RESULTS@#Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group.@*CONCLUSIONS@#The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.

Research on clinical effects of non-bracket invisible appliance on the mandibular advancement treatment of skeletal Class Ⅱ growing patients with mandibular retrusion / 口腔医学

Objective@#To evaluate the effects of non-bracket invisible appliance mandibular advance(MA) on skeletal Class Ⅱ growing patients with mandibular retrusion.@*Methods@#Nineteen skeletal Class Ⅱ growing patients with mandibular retrusion who were treated in the department of stomatology of Changshu traditional Chinese medicine hospital from January 2018 to May 2021 were selected. They had an average age of (12.32±1.51) years old. The treatment group consisted of 10 children who were treated with MA. The control group consisted of 9 children who refused to treat their malocclusion. Cephalometrics of all patients were taken before and after the observation or treatment. The cephalometric data of two groups were analyzed. @*Results@#Compared with the control group, in the treatment gruop SNB angle, L1-NB angle, L1-NB distance, L6-MP distance, Z angle increased significantly (P<0.05);Co-Go distance, Co-Gn distance, SL increased more greatly than the control group; ANB angle, U1-SN angle, U1-NA angle, U1-NA distance, L1-MP distance, FCA angle decreased significantly (P<0.05); SE did not change significantly in the treatment group, but increased significantly in the control group (P<0.05).@*Conclusion @# MA can promote mandibular growth and improve lateral profile. The angle of the lower teeth and the angle of the mandible plane can be controlled by MA appliance.

Decompensation effectiveness and alveolar bone remodeling analysis of mandibular anterior teeth after preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusion / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the decompensation effectiveness and alveolar bone remodeling of mandibular anterior teeth after preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusion using lateral cephalogram and cone-beam computed tomography (CBCT).@*METHODS@#Thirty high-angle patients with skeletal class Ⅱ malocclusion who had received preoperative orthodontic treatment and orthognathic surgery in Peking University School and Hospital of Stomatology between Ja-nuary 2017 and August 2022 and had taken lateral cephalogram and CBCT before and after preoperative orthodontic treatment were selected. Items were measured with lateral cephalogram including: The lower central incisor (L1)-Frankfort plane angle (L1-FH), the L1-mandibular plane angle (L1-MP), the L1-nasion-supramental angle (L1-NB) and the vertical distance from the incisal edge of lower central incisor to NB line (L1-NB distance), etc. The incidence of dehiscence/fenestration and the length of dehiscence at labial side (d-La) and lingual side (d-Li) were measured using CBCT. Pearson correlation analysis was used to evaluate the correlation between the changes of d-Li of L1 and age, duration of preoperative orthodontic treatment and the cephalometric measurements before preoperative orthodontic treatment to screen out risk factors affecting the periodontal risk of preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusions.@*RESULTS@#After preoperative orthodontic treatment, L1-FH, L1-MP, L1-NB and L1-NB distances changed by 11.56°±5.62°, -11.13°±5.53°, -11.57°±5.43° and (-4.99±1.89) mm, respectively, and the differences were all statistically significant (P < 0.05). Among the 180 measured mandibular anterior teeth, 45 cases with labial dehiscence/fenestration before preoperative orthodontic treatment (T0) had no longer labial dehiscence/fenestration after preope-rative orthodontic treatment (T1); 142 cases without lingual dehiscence/fenestration at T0 had lingual dehiscence/fenestration at T1. After preoperative orthodontic treatment, the d-La of lower lateral incisors (L2), lower canines (L3) and lower anterior teeth (L1+L2+L3) decreased by (0.95±2.22) mm, (1.20±3.23) mm and (0.68±2.50) mm, respectively, and the differences were statistically significant (P < 0.05); the d-Li of L1, L2, L3 and L1+L2+L3 increased by (4.43±1.94) mm, (4.53±2.35) mm, (3.19±2.80) mm and (4.05±2.46) mm, respectively, and the differences were statistically significant (P < 0.05). The increase of d-Li of L1 was positively correlated with L1-FH (r=0.373, P=0.042).@*CONCLUSION@#This study showed that high-angle patients with skeletal class Ⅱ ma-locclusion could achieve ideal decompensation effect of mandibular anterior teeth after preoperative orthodontic treatment with bilateral mandibular first premolars extracted, but the lingual periodontal risk of mandibular anterior teeth was increased. This risk could be correlated to L1-FH before preoperative orthodontic treatment, which should be paid more attention in the design of orthodontic-orthognathic surgical treatment.

Changes in canine position during maxillary molar distalization with mini-implant and CD appliance: an in vitro study / 口腔疾病防治

Objective@#To investigate changes in the three⁃dimensional position of the maxillary canine during the distal movement of the maxillary first molar by a mini⁃implant combined with a CD appliance.@*Methods@#Ten typodont models of class II malocclusion were selected, and one side was randomly chosen as the experimental group. The CD ap⁃ pliance was bonded to the maxillary canine and first molar of the experimental group, and 1.2 mm stainless steel wire was bent as the anchorage, which was fixed on the model to simulate mini⁃implants implanted in the zygomatic alveolar ridge. Then, 180 g orthodontic force was applied to the canine of the experimental group; the other side was recognized as the control group and was not used for strengthening. Six mini⁃implants were implanted in different parts of the mod⁃ el and used as a reference before and after the experiment. The models were placed in an incubator and heated at 56 ℃ in a water bath for 2 min. The models were scanned before and after thermostatic water bath treatment with a 3⁃shape scanner. Then, the digital models were overlapped through the reference points, and the positions of the canines and first molars were measured before and after the experiment.@*Results@#The sagittal movement distance of the first molar in the experimental group was ( 0.25 ± 0.33) mm, and the vertical movement distance was (0.25 ± 0.28 )mm, which was significantly different from the control group (P < 0.05), while the transverse change was not significantly different (P > 0.05). There was no significant difference in the root position of the first molar in the experimental group (P > 0.05). The lateral and vertical displacement distances of the maxillary canine crown in the experimental group were (4.03 ± 2.11) mm and (1.86 ± 1.01) mm, respectively, which were significantly different from those in the control group (P < 0.001), while the sagittal changes showed no significant differences (P > 0.05). In the experimental group, there was no significant difference in the position of the apex of the maxillary cusp (P > 0.05).@*Conclusion@#Our in vitro study showed that the maxillary canines inclined buccally accompanied by a small amount of intrusion during molar distaliza⁃ tion by a mini⁃implant combined with a CD appliance.

Morphological change analysis based on cone beam CT of the upper airway for obstructive sleep apnea syndrome patients treated with oral appliance in skeletal class Ⅱ malocclusion with different vertical patterns / 华西口腔医学杂志

OBJECTIVE@#To analyze the morphological changes in the upper airway of obstructive sleep apnea syndrome (OSAS) patients treated with oral appliance in skeletal class Ⅱ malocclusion with different vertical features by using cone beam CT (CBCT).@*METHODS@#Thirty-six patients diagnosed with OSAS by polysomnography and daytime sleepiness scale and skeletal class Ⅱ malocclusion were treated with oral appliance for 4 months. The changes based on CBCT in the morphology of glossopharyngeal and palatopharyngeal before and after treatment in OSAS patients with different vertical features were compared.@*RESULTS@#After treatment with oral appliance, the glossopharyngeal and palatopharyngeal morphologies of patients with mild OSAS showed significant changes. After treatment with oral appliance, the glossopharyngeal morphology of all patients showed significant changes (P<0.05). The palatopharyngeal morphology of patients in the lower and average groups also exhibited significant changes (P<0.05). Sagittal changes in the glossopharyngeal measurements of high-angle patients demonstrated significant difference, whereas the other measured values showed no significant difference.@*CONCLUSIONS@#The morphological changes in the upper airway were significant in OSAS patients with lower and average vertical patterns when treated with oral appliance, but the changes in high vertical patterns were not significant.

Functional clear aligner treatment of class Ⅱ malocclusion in teenagers / 华西口腔医学杂志

Class Ⅱ malocclusion is a common orofacial deformity that could harm the facial esthetics and oral function. Two-stage treatment strategy always applies to functional and skeletal (mild and moderate) class Ⅱ malocclusion with man-dibular retrognathism in teenagers. Traditional functional orthopedic appliances are less comfortable and inconvenient to correct the dental arches, making the treatment duration long. With the rapid progress of digital technology and material science, functional clear aligners that offer comfort have emerged. Functional clear aligners can combine orthopedic and orthodontic treatments to correct the jaw relationship and align the dental arch, thereby shortening the treatment duration. This paper emphasizes the treatment key points, and clinical experience of using functional clear aligners.

Application and research progress of the surgery-first approach in the treatment of dento-maxillofacial deformities / 口腔疾病防治

@#For patients with dento-maxillofacial deformities who receive orthodontic-orthognathic combined treatment, the conventional treatment approach is preoperative orthodontic-orthognathic surgery-postoperative orthodontics. However, with the development of techniques used in orthodontic and orthognathic treatment, the surgery-first approach (SFA), namely, orthodontic surgery-postoperative orthodontics, has been widely used currently and displays several advantages, such as improving the treatment efficiency and providing patients with more satisfaction. This review provides a brief discussion and review of SFA concerning its development, indications, advantages and disadvantages, outcomes and stability, and the application and research progress of SFA in orthodontic-orthognathic combined treatment for patients with maxillofacial deformity. The literature review results showed that compared with the conventional treatment approach, SFA has relatively strict indications, which usually include patients with skeletal class Ⅱ/Ⅲ malocclusion, skeletal open bite, and bimaxillary protrusion or patients with facial asymmetry but who require little preoperative orthodontic treatment or removal of the compensation of the dental arch, specifically as follows: ①well-aligned to mildly crowded anterior teeth, ②flat to mild curve of Spee, ③normal to mildly proclined/retroclined incisor inclination, ④acceptable arch coordination, ⑤extensive occlusal contact between the upper and lower dentition requiring at least 3 occlusal contacts. Any occlusion that may affect the outcome of surgery or final result of the overall treatment, as well as any disease that may jeopardize the healing process after surgery, is regarded as a contraindication. Furthermore, SFA has potential disadvantages, such as a possible higher incidence of complications, including unstable occlusion and malunion of bones, which still require further research to be confirmed. Most researchers believe that no significant difference occurs between the outcome and stability of the two approaches. However, currently, we still need a sufficient sample size of prospective studies to provide accurate evidence.

Relationship between depth of the curve of Spee and dentalfacial morphology in Angle Class Ⅱ maloclusion patients / 口腔疾病防治

Objective @#To compare the depth of the curve of Spee in Angle classⅡ malocclusion patients with different vertical skeletal patterns and to investigate the relationship between the depth of the curve of Spee and dentofacial morphology. @*Methods @#101 Angle classⅡ malocclusion patients were selected and randomly divided into 3 groups based on their GoGn-SN angles-high angle, average angle and low angle. Lateral cephalograms and dental models of all patients were evaluated to analyze Spee curve depth difference among different groups, Correlation analysis and a multiple linear regression analysis were performed to determine the relationship between the depth of the curve of Spee and all selected cephalometric variables.@*Results@# There was statistical difference in depth of the curve of Spee among different groups P < 0.05. The depth of the curve of Spee was least in the high angle group and greatest in the low angle group. GoGn-SN angle had statistically significant negative correlation with the depth of the curve of Spee, r = 0.428, P = 0.000, ODI, S-Go/N-Me、L7-GoGn angle had statistically significant positive correlation with the depth of the curve of Spee, r = 0.381, 0.357, 0.333, P = 0.000, 0.000, 0.001. The multiple linear regression analysis with stepwise method showed GoGn-SN angle had significant contribution to the depth of the curve of Spee. In Angle classⅡ malocclusion patients, there was statistical difference in depth of the curve of Spee among different vertical skeletal patterns@*Conclusion @#The depth of the curve of Spee is correlated with dentofacial morphology, GoGn-SN angle had significant contribution to the depth of the curve of Spee, which should be taken into consideration during orthodontic diagnosis and treatment.

The effect of unilateral Forsus appliance in the treatment of ClassⅡmalocclusion subdivision / 口腔疾病防治

Objective @# To assess the result of treatment in ClassⅡmalocclusion subdivision with unilateral Forsus appliance. @*Methods @#23 patients with ClassⅡmalocclusion subdivision were selected, who were treated with Straight wire fixed appliance in combination with unilateral Forsus appliances while another 27 patients were untreated as control group. Lateral cephalographs were taken before and after the comprehensive treatment, and the indicators of dental, skeletal, and soft tissue profile were measured.@*Results @#The Forsus appliance can correct ClassⅡmalocclusion subdivision through distalizing the upper teeth and moving the lower teeth mesially. Midline can be corrected at the same time. There was a statistically significant difference in the amount of tooth movement (P < 0.05). @*Conclusion @#Forsus appliance is an effective device for treating ClassⅡmalocclusion subdivision, which can induce significant dental and soft tissue changes.

Prediction on vertical craniofacial bone relationship in patients withskeletal class Ⅱ malocclusion based on genetic algorithms method / 吉林大学学报(医学版)

Objective:To establish the quantitative relationship equation of the crantiofacial vertical points in the skeletal classⅡ malocclusion patients with various vertical types by using genetic algorithms method,and to express the measured values in the patients with different gender with the same formula.Methods:A total of 155 skeletal class Ⅱ malocclusion patients without treatment,aged from 10 to 18 years old,were selected and divided into high-angle group(n=50),average-angle group(n=58),low-angle group(n=47);5 samples were randomly selected in each group as the test samples,the rest as the experimental sample.The cephalometic radiographs were performed and measured.The relevant influencing factors of craniofacial structure were ensured.The genetic algorithm was used to optimize the equation parameters to obtain the correlation equation.The error between the predicted value and the measured value was compared.Results:The various parameters had no significant differences between different gender in high-angle,average-angle and low-angle groups(P>0.05);then the men and the women with same type were combined,most of the indicators had statistically significant differences between three groups (P0.05).Conclusion:The quantitative relationship equation of the crantiofacial vertical points in the skeletal class Ⅱmalocclusion patients with various vertical types established with genetic algorithms may show the vertical quantitative relationship and predict the growth to a certain degree.

An efficacy comparison between pre-adjusted and Begg appliance on the dentofacial morphology in Angle class Ⅱ division 1 extraction cases treated by light archwire technique / 实用口腔医学杂志

Objective:To compare the effects between Begg and pre-adjusted appliance on dentofacial morphology in Angle class Ⅱ division 1 extraction cases treated by light archwire technique.Methods:28 cases with Angle class Ⅱ division 1 who needed maximum maxillary incisor retraction were divided into 2 groups (MBT pre-adjusted and Begg group) and treated by light archwire technique.4 first premolars were extracted in all patients.Lateral cephalometric films were analyzed before and after treatment.Results:The upper incisors were intruded (0.18 ± 0.32)mm and (0.77 ± 0.91) mm in pre-adjusted and Begg group respectively (P ＜ 0.05).The other differences of cephalometric analyses between 2 groups were not significant (P ＞ 0.05).Conclusion:The effects were almost same with pre-adjusted and Begg appliances in Angle class Ⅱ division 1 extraction cases treated by light archwire technique except for that the latter is better than the former in vertical control of maxillary anterior teeth.

Meta-analysis of the condylar position changes produced by functional appliances in class Ⅱ malocclusion / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to analyze the condylar position changes produced by functional appliances in class Ⅱ malocclusion by systematic review.</p><p><b>METHODS</b>Electronic search was conducted using Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals, Medline, Embase, Pubmed, and Cochrane Central Register of Controlled Trials. Studies on condylar position changes produced by functional appliances in class Ⅱ malocclusion were included. Risk of bias assessment and data extraction of included studies were conducted by two reviewers independently. The meta-analysis was carried out using Revman 5.1.</p><p><b>RESULTS</b>Six studies were included (five high quality and one low quality). The condylar position showed no changes after Herbst treatment. The condylar posterior space after Twin-block treatment averagely increased by 0.31 mm (P<0.000 01), whereas the condylar anterior space averagely reduced by 0.32 mm (P<0.000 01).</p><p><b>CONCLUSIONS</b>Twin-block appliance enables forward movement of the condylar position. This result contributes to the correction of class Ⅱ malocclusion.</p>

A cone-beam CT study on alveolar bone morphology in anterior teeth area of adult skeletal Class Ⅱ mal-occlusion subjects with different vertical skeletal types / 实用口腔医学杂志

Objective:To study the alveolar bone morphology in the anterior teeth area of the skeletal Class Ⅱ malocclusion subjects with different vertical skeletal types.Methods:64 patients with skeletal Class Ⅱ malocclusion and 15 subjects with normal occlusion were included.The alveolar bone structure of the anterior teeth were observed using CBCT.Results:The labial and lingual alveolar bone height and the alveolar bone thickness of the incisors of the patients were much lower than those of the normal controls.The height of labial and lingual alveolar bone and the alveolar bone thickness of anterior teeth in high-angle subgroup were lower than those in low-angle subgroup.Conclusion:The thickness of the anterior teeth alveolar bone of skeletal Class Ⅱ malocclusion is low,espe-cially in the high-angle group.

Clinical study of corticotomy assisted orthodontic treatment for mild skeletal Class Ⅱ malocclusion / 实用口腔医学杂志

Objective:To investigate the effects of corticotomy assisted orthodontic treatment for mild skeletal Class Ⅱ malocclusion. Methods:7 adult patients with mild skeletal Class Ⅱ division 1 malocclusion were included and underwent corticotomy assisted ortho-dontic treatments.3D measurements and analysis of CBCT data before and after treatment were conducted.Results:The average dura-tion of upper anterior teeth retraction was 3.2 months.After treatment,obvious retraction of up incisiors with the retraction of maxillary alveolar bone and the upper lip backward and downward movement were observed.Conclusion:Corticotomy assisted orthodontic treat-ment is effective in the treatment of mild skeletal Class Ⅱ malocclusion by the retraction of uper anterior teeth,alveolarar bone and soft-tissue profile improvement.

Clinical effects of pendulum and straight wire technology in patients with fully erupted maxillary second molar / 中华医学美学美容杂志

ObjectiveTo investigate the clinical effect of pendulum and straight wire technology in patients with fully erupted second molar.MethodsPatients with Angle class Ⅱ malocclusion were chosen.Control group included patients without erupted second molar.Experimental group included patients with completely erupted second molar.Pendulums were used in two groups to distalize maxillary molars.Then straight wire orthodontic treatment had been performed until treatment was over.Cephalograms of each stage were analyzed.ResultsIn the experimental group,mesiobuccal cusp of first molar was distalized for 4.62 mm,geometric center was distalized for 3.75 mm,about 81 percent of the movement of mesiobuccal cusp.In control group,mesiobuccal cusp of first molar was dis talized for 5.78 mm,geometric center was distalized for 3.20 mm,about 55 percent of the movement of mesiobuccal cusp.It turned out first molar was distalized in both groups,but more rotation took place in control group than that in the experimental group.ConclusionsPendulum can distalize maxillary first and second molars in patients with completely erupted second molar.The pendulum and straight wire technology can treat these patients successfully.

Clinical evaluation of the pendulum appliance on distalization of maxillary molars / 实用口腔医学杂志

objective: To evaluate the effects of the pendulum appliance on arch length, arch width, overbite and overjet. Methods: Pendulum appliances were applied for distalization of maxillary molars in 37 patients whith class Ⅱ malocclusion and 1-Ⅱ degree crowded dentition in upper dental arch. Pretreatment and posttreatment model analysis was conducted. Results: 37 patients treated for 18.2?4.5 weeks with pendulum appliance were accomplished . The increase of arch arc length between the maxillary first molars was (17.36?4.38) mm, the decrease of anterior arch width (-3.04?1.59) mm, and the decrease of posterior arch width (-1.29?2.01) mm . Differences between the pretreatment and posttreatment were significant, including arch arc length between the maxillary first molars ( P

A study on a transpalatal arch for reinforcing anchorage / 实用口腔医学杂志

砄bjective: To evaluate the effect on a transpalatal arch on reinforcing anchorage. Methods: 12 cases with ClassⅡ Division 1 malocclusion were selected and treated with a transpalatal arch for reinforcing anchorage. Results: ①The forward displacement of the first maxillary molar (6 Ptmo, 6 So, 6CR So and 6AP So) , the backward displacement(1 Ptmo and 1 So ) and the reduction of the axial inclination (1 NA and 1 SN) of the upper incisors were increased( P 0.05);③The forward displacement of the first maxillary molar was less than one third of the extraction space ( P