Short-term effects produced by rapid maxillary expansion and facemask therapy in Class III patients with different vertical skeletal relationships

Objective:To evaluate the dentoskeletal short-term effects of rapid maxillary expansion and facemask therapy (RME/FM) in a sample of Class III patients showing different vertical skeletal relationships.Materials and Methods:Seventy-nine patients (35 females and 44 males) having Class III malocclusion were consecutively treated using RME/FM therapy with application of the protraction force in a downward and forward direction and inclination of about 30° to the occlusal plane. All patients were evaluated at the beginning (T1; mean age, 7.7 years) and at the end (T2; mean age, 9.2 years) of orthopedic therapy and divided into three groups according to their vertical skeletal relationships: normal group (NG), hypodivergent group (HypoG), and hyperdivergent group (HyperG). Statistical comparisons between the three groups were performed on the starting forms (T1), the final forms (T2), and the treatment changes (T1–T2) using the ANOVA with Tukey''s post hoc tests.Results:Favorable modification in terms of maxillary advancement (changes in SNA ranging from 1.4° to 1.8°) and intermaxillary sagittal skeletal relationships (changes in Wits appraisal ranging from 2.5 mm to 3.5 mm) were recorded in all groups. The three groups showed no statistically significant differences in changes in either sagittal or vertical skeletal variables.Conclusions:The various vertical skeletal features do not influence the short-term outcomes of RME/FM therapy.     

Comparison of double-plate appliance/facemask combination and facemask therapy in treating Class III malocclusions

Objective:To compare the treatment effects of double-plate appliance/facemask (DPA-FM) combined therapy and facemask (FM) therapy in treating Class III malocclusions.Materials and Methods:The material consisted of lateral cephalometric radiographs of 45 children with skeletal and dental Class III malocclusion. The first treatment group comprised 15 patients (mean age  =  11 years) treated with FM. The second treatment group comprised 15 patients (mean age  = 10 years 9 months) treated with DPA-FM. The third group comprised 15 patients (mean age  =  10 years 5 months) used as controls. The paired t-test was used to evaluate the treatment effects and changes during the treatment and observation period in each group. Differences between the groups were determined by variance analysis and the Duncan test.Results:With the DPA-FM and FM appliances, the SNA and ANB angles increased significantly. These changes were statistically different compared with the control group. Lower facial height showed a greater increase in both treatment groups than in the control group. Molar relation showed a greater increase in the DPA-FM group than in the FM group. The increase in U6/ANS-PNS angle in the FM group was significantly different from the DPA-FM and control groups. The L1/NB angle and Pg-T increased significantly only in the FM group, but no significant difference was found between the treatment groups.Conclusions:In the treatment of Class III malocclusion, both appliances were effective. The significant sagittal changes in the lower incisors and pogonion in the FM group compared with the nonsignificant changes in the DPA-FM group might be due to the restriction effect of acrylic blocks in the DPA-FM group.     

Modified tandem traction bow appliance compared with facemask therapy in treating Class III malocclusions

Objective:To compare the effects of the modified tandem traction bow appliance (MTTBA) and the facemask in treating patients with Class III malocclusion.Materials and Methods:The material consisted of the pre-post treatment\pre-post observation lateral cephalograms of 65 subjects with skeletal and dental Class III malocclusion. In the first group 21 patients (mean age: 10 years, 6 months) were treated with a Delaire-type facemask (FM). In the second group 22 patients treated (mean age: 10 years) with MTTBA. The remaining 22 children (mean age: 9 years, 7 months) were observed without treatment for 11 months.Results:Increase in SNA, N-FH ⊥ A, and ANB angles were significantly greater in the treatment groups compared to the control group. However, ANB angle showed a significantly greater increase in the FM group (2.8 ± 0.30°) than in the MTTBA group (2.0 ± 0.18°). The overjet and molar relation increased significantly in both treatment groups, but in the FM group (5.2 ± 0.40 mm) increase in overjet was significantly greater than in the MTTBA group (4.0 ± 0.27 mm). Mesial movement of upper molar and incisor were found to be greater in the FM group compared to the modified TTBA group.Conclusions:Both appliances were found to be effective in the treatment of Class III malocclusion. Their skeletal and dental effects showed differences due to their design.     

Treatment outcomes of various force applications in growing patients with skeletal Class III malocclusion:: A comparative lateral cephalometric study

ObjectivesTo evaluate skeletal, dentoalveolar, and soft tissue changes between intraoral light force application and extraoral heavy force application in growing patients with skeletal Class III malocclusion.Materials andMethods: A retrospective study was conducted with pretreatment and posttreatment lateral cephalometric data from 50 subjects with skeletal Class III malocclusion. In the first group (15 boys, 10 girls; 8.67 ± 2.13 years old), each subject wore a biocreative horseshoe appliance (CHS) with two Class III elastics that exerted a force of 200 g. In the second group (13 boys, 12 girls; 8.96 ± 1.82 years old), each subject wore a Petit-type facemask and a lingual arch with hooks fixed to the maxillary arch with a total force of 700 g. Both groups of patients were instructed to wear the appliance approximately 14 hours a day, and 22 linear measurements and 8 angular measurements were evaluated. Changes of measurements from each group were compared by paired t-tests, considering a 5% significance level.ResultsForward growth of the maxilla, improvement of the maxilla–mandible relationship, and upper incisor flaring were achieved in both groups without any statistically significant difference between them. Lateral cephalometric analysis also showed that U1 exposure, IMPA (Angle between mandibular plane and mandibular incisor axis), FMIA (Angle between FH plan and mandibular incisor axis), and L1-APog (Angle formed by the intersection of tooth axis of lower incisor and A-Pog line, Distance from lower incisor edge to A-Pog line) showed statistically significant differences. Lower incisors were inclined lingually in the CHS group.ConclusionsDuring treatment of skeletal Class III malocclusion, the CHS with light Class III intermaxillary elastics therapy exhibits similar orthopedic changes to the maxillary complex and more dental changes to the lower anterior teeth compared with facemask therapy.     

Management of the Class III malocclusion treated with maxillary expansion,facemask therapy and corrective orthodontic. A 15-year follow-up

The facial growth of Class III malocclusion worsens with age, in this case, the early orthopedic treatment, providing facial balance, modifying the maxillofacial growth and development. A 7.6-year old boy presented with Class III malocclusion associated with anterior crossbite; the mandible was shifted to the right and the maxilla had a transversal deficiency. Rapid maxillary expansion followed by facemask therapy was performed, to correct the anteroposterior relationship and improve the facial profile. The patient was followed for a 15-year period, after completion of the treatment, and stability was observed. Growing patients should be monitored following their treatment, so as to prevent malocclusion relapse.     

Characterization of facial asymmetry in skeletal Class III malocclusion and its implications for treatment

Jaw deviation is frequently seen in Class III patients. The aim of the study was to investigate asymmetric features of skeletal, dental and soft tissues in three types of jaw asymmetry based on our previously reported classification system. The cone-beam computed tomography (CBCT) images of 70 Class III patients were analysed. Group 1 patients showed large shift of menton and synchronous but smaller ramus deviation. The maxillomandibular complex had roll and yaw rotations to the menton-deviation side. Maxillary and dental asymmetry was obvious in transverse and vertical dimensions. Cant of occlusal plane and lip line was apparent. Group 2 patients also exhibited menton and ramus deviation to the same side but the discrepancy in ramus width was larger than menton shift. Asymmetry in Group 2 resulted from a bodily side shift of the maxillomandibular complex without obvious rotation. Group 3 patients had menton and ramus deviated in opposite directions which seemed secondary to a yaw rotation. Double-jaw surgery is generally required for Groups 1 and 3 while Group 2 patients may be successfully treated by mandibular surgery only provided that arch width discrepancy can be managed by orthodontic measures.     

Relapse patterns of two-jaw surgical correction in patients with skeletal Class III malocclusion and different vertical facial types

The aim of this study was to evaluate postoperative relapse after the surgical correction of skeletal Class III deformities of various facial patterns as a guide to surgical planning. A retrospective cohort study of 90 consecutive patients with skeletal Class III malocclusion who underwent bimaxillary surgery was performed. The surgical outcomes and postoperative stability were compared. The primary predictor variable was vertical facial type, which was classified into three groups according to the Frankfort mandibular plane angle (FMA). The primary outcome of angular and linear measurements was obtained using serial cone beam computed tomography scans obtained at time points of preoperative, 1 week after surgery, and orthodontic debonding. No significant difference in skeletal relapse was observed in patients with the different vertical facial types. The mandible displayed a forward and upward relapse in all three groups postoperatively. The patients with a low FMA exhibited a more consistent mandibular relapse pattern than those with a normal or high FMA. These findings suggest that bimaxillary surgery is clinically stable for mandibular prognathism regardless of the vertical facial pattern. However, 1–1.5 mm of overcorrection in the mandible setback should be considered in patients with a low FMA, because of the greater facial depth and consistent forward and upward mandibular relapse pattern.     

Comparison of facemask therapy effects using skeletal and tooth-borne anchorage:: A longitudinal retrospective study

ObjectivesTo investigate long-term outcomes of dentoskeletal changes induced by facemask therapy using skeletal anchorage in Class III patients and compare them to those of conventional tooth-borne anchorage.Materials and MethodsThis retrospective study included 20 patients who received facemask (FM) therapy with miniplates as anchorage for maxillary protraction (Miniplate/FM group, 10.6 ± 1.1 years old [mean ± SD]) and 23 patients who were treated with facemask with rapid maxillary expander (RME/FM group, 10.0 ± 1.5 years old [mean ± SD]). Dentoskeletal changes were evaluated using lateral cephalograms at pretreatment (T1), after facemask therapy (T2), and at the post-pubertal stage (T3). Cephalometric changes were compared between groups and clinical success rates at T3 were evaluated.ResultsSNA and A to N perpendicular to FH increased significantly more in the Miniplate/FM group than in the RME/FM group when comparing short-term effects of facemask therapy (T1–T2). ANB, Wits appraisal, Angle of convexity, mandibular plane angle, and overjet decreased significantly more in the RME/FM group than in the Miniplate/FM group after facemask therapy (T2–T3). A more favorable intermaxillary relationship was observed in the Miniplate/FM group than in the RME/FM group in long-term observations (T1–T3). Clinical success rate at T3 was 95% in the Miniplate/FM group and 85% in the RME/FM group.ConclusionsFacemask therapy with skeletal anchorage showed a greater advancement of the maxilla and more favorable stability for correction of Class III malocclusion in the long-term than conventional facemask therapy with tooth-borne anchorage.     

垂直骨型对Ⅱ1类错(牙合)患者面下1/3软组织结构影响的研究

目的:研究不同垂直骨面型的成人Ⅱ1类错患者面下1/3软组织结构的差异.方法:选取未经正畸治疗的180例成人Ⅱ1类错患者分为高角(SN-MP角＞40°)、均角(29°≤SN-MP角≤40°)、低角(SN-MP角＜29°)3组.每组各有男、女30人.在头颅侧位定位片上分别测量上唇、下唇、颏部软组织结构的厚度与长度,并分析其在不同垂直骨面型个体间的差异.结果:男、女高角型Ⅱ1类错患者上唇长度、下唇长度都较均角和低角患者明显增高(P＜0.05);男性高角型Ⅱ1类错(牙合)患者下唇基部厚度也较均角和低角患者明显增高(P＜0.05),而女性低角角型Ⅱ1类错患者下唇基部厚度较均角和高角患者明显减低(P＜0.05).女性高角组患者的颏顶点处软组织厚度明显低于均角组和低角组患者(P＜0.05),而男性不同垂直骨面型Ⅱ1类错患者颏部软组织结构则未见明显的差异(P＞0.05).结论:垂直向骨型因素对Ⅱ1类患者面下1/3软组织以厚度和长度为代表的结构有明显的影响.     

Time and pattern of the fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion

Objectives:To investigate the time and pattern of fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion using cone-beam computed tomography (CBCT).Materials and Methods:A total of 262 CBCT images were collected: 140 skeletal Class I (0° < ANB < 4°; 71 males, 69 females) and 122 skeletal Class III (ANB ≤ 0°; 61 males and 61 females). The fusion stages were identified using CBCT images of a six-stage system defined by the appearance of osseous cores and ossifying vestige in the synchondrosis. The age distributions of each stage and the pattern of fusion were evaluated.Results:The stages of fusion progressed with increasing age (P < .05, r = .824), and the age distributions in the female groups were generally 1 to 3 years younger than those in the male groups. However, no significant differences were observed between the skeletal Class I and Class III groups regarding the time of ossification of the synchondrosis. The osseous cores appeared most frequently in the supero-center part, followed by the mid-center part of the synchondrosis.Conclusions:The time and pattern of fusion of the spheno-occipital synchondrosis are not apparently different between patients with Class I malocclusion and those with Class III malocclusion. The osseous cores appear frequently in the supero-center and mid-center of the synchondrosis with various patterns before the end of the pubertal growth spurt period.     

骨种植钉前牵引对骨性Ⅲ类错患者软硬组织侧貌的影响

目的研究采用骨种植钉前牵引对骨性Ⅲ类错患者软、硬组织侧貌的改变。方法选取18例需行前牵引矫治的生长发育期骨性Ⅲ类错患者,采用双侧上颌颧牙槽嵴植入骨种植钉配合面框式前牵引,平均治疗时间为9个月,力值为（3.5±0.1）N。治疗前后头影测量采用Legan&Burstone软组织分析法以及相关硬组织测量,分析比较患者治疗前后软、硬组织变化情况。结果所有患者Ⅲ类错均得到改善,鼻底趋于丰满,颏部顺时针旋转,侧貌由凹面型变为直面型,下唇突度减小,软组织上下面高比、鼻唇角、上唇突度及颏唇沟深度无明显变化。上前牙无明显变化,下前牙舌倾,上颌骨向前生长,A点前移,SNA、ANB增大;SNB减小,下颌骨顺时针旋转。结论骨种植钉前牵引可促进上颌生长,使面中份丰满,且对上颌前牙轴倾度无影响,从而纠正骨性Ⅲ类错。     

Three-dimensional evaluation of soft tissue change gradients after mandibular setback surgery in skeletal Class III malocclusion

Objective:To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects.Materials and Methods:The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis.Results:Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P < .001 and P < .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P < .001; Ch, 3.4 mm and 0.8 mm, both P < .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B′, 6.7 mm; Pog′, 6.7 mm; Me′, 6.6 mm; P < .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P < .001). Chin height (B′-Me′) was decreased because of backward and upward movement of Me′ (3.1 mm, P < .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch_Rt-Ls-Ch_Lt, 5.7°; Ch_Rt-Stm-Ch_Lt, 6.4°, both P < .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch_Rt-Li-Ch_Lt, 10.8°; Ls-Stm-Li, 23.5°, both P < .001) because of the larger backward movement of Li than labrale superius (Ls).Conclusions:Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch.     

成人轻度骨性Ⅲ类错牙合不同拔牙模式矫治的侧貌分析

目的：比较不同拔牙模式矫治的轻度骨性Ⅲ类错牙合成人患者的侧貌变化。方法：选择40例诊断为设计拔除4个前磨牙或第三磨牙矫治的轻度骨性III类错牙合的成人病例,分为两组,每组各20例。用头影测量分析法比较矫治前后的变化以及软硬组织的相关性。结果：拔除前磨牙组变化主要在于内收上下前牙。拔除第三磨牙组在于唇倾上前牙,软组织改变分别是内收下唇和唇倾上唇代偿（P<0．05）。软硬组织的变化具有一定相关性（P<0．05）。结论：不同拔牙模式对轻度骨性Ⅲ类错牙合患者矫治后侧貌的改变是有差别的,但在一定程度上都能改善凹面型和颏部形态。     

未治疗的安氏Ⅲ类错[牙合]下颌骨的生长旋转特点

目的：观察未治疗的安氏Ⅲ类错[牙合]患者颈椎骨龄CS1-CS6期下颌骨的生长旋转特点,为安氏Ⅲ类错[牙合]患者的生长改向提供参考。方法：收集安氏Ⅲ类错[牙合]患者329例,男144例,女185例;拍摄头颅定位侧位片,按性别和颈椎CVM分期分组,应用Winceph8．0头影测量软件测量下颌角（ArGo＇Me）、[牙合]平面角（Occlusalp1．to SN）、下颌平面角（Go—Gnto SN）和面高比（S—Go／N—Me）值,数据采用SPSS16．0方差分析后进行组间多重对比（LSD—t检验）。结果：男性安氏Ⅲ类错[牙合]患者SN—OP呈现先升后降趋势,CS3和CS6组间差异有统计学意义（P〈0．05）;在CS4-CS6期,ArGo’Me逐渐减小,S-Go／N—Me逐渐增加,CS4和CS6组间差异明显（P分别为0．041和0．009）。女性安氏Ⅲ类错[牙合]患者SN—OP、SN—GoGn和ArGo＇Me均在CS4-CS5有明显减小（P〈0．05）;S-Go／N—Me在CS4-CS5期增加（P=0．006）。结论：安氏Ⅲ类错骀患者下颌骨生长总体上呈向前上旋转趋势,在CS4期之后旋转明显。提示对安氏Ⅲ类错[牙合]患者进行生长改向治疗时,应考虑到生长发育高峰期之后下颌骨的前上旋转对预后的影响。     

Association of the three-dimensional skeletal variables with self-recognition of facial asymmetry in skeletal Class III patients

ObjectivesTo investigate the association between three-dimensional (3D) skeletal variables and self-recognition of facial asymmetry in skeletal Class III patients.Materials and MethodsQuestionnaires and cone beam computed tomography of 74 patients (42 men and 32 women; mean age: 22.8 ± 4.5 years) with skeletal Class III and facial asymmetry were collected retrospectively. Patients were classified into three groups: group Sy (recognition of symmetry), group NS (not sure), and group Asy (recognition of asymmetry), according to their responses to the questionnaires. To assess 3D anatomic differences in the maxillomandibular region, six 3D hard tissue variables: maxillary height, ramal length, frontal ramal inclination (FRI), lateral ramal inclination (LRI), mandibular body length (Mn BL), and mandibular body height (Mn BH) were compared among the three self-recognition groups. Six 3D hard tissue variables and Menton deviation were reduced into three factors and their association with the self-recognition of facial asymmetry was investigated.ResultsMaxillary height, FRI, LRI, Mn BH, and Menton deviation demonstrated significant differences among the three self-recognition groups. The reduced factors, which consisted of transverse and vertical parameters, and vertical parameter of the mandibular corpus, demonstrated significant differences among the three self-recognition groups. The difference in Mn BH influenced the self-recognition of facial asymmetry.ConclusionsBoth the transverse and vertical parameter of the skeleton were determinant in self-recognition of facial asymmetry. Identification of the skeletal difference in the lateral view involving LRI and Mn BH should be included for assessment of facial asymmetry.     

Efficacy of short-term chincup therapy for mandibular growth retardation in Class III malocclusion: A systematic review

Objective:To assess the efficacy of chincup therapy for mandibular growth retardation in early orthopedic treatment of Class III malocclusion.Materials and Methods:An electronic search for articles reporting randomized clinical trials, controlled clinical trials, and cohort studies testing the efficacy of chincup appliance for Class III malocclusion published up to the present was done through four databases: Cochrane Central Register of Controlled Trials (CENTRAL; to March 2010), MEDLINE (1950–March 2010), EMBASE (1980–March 2010), and CBM (1978–March 2010). Study quality assessment and data extraction were done by two reviewers independently. Meta-analysis was done with the assistance of Revman 5.01.Results:The search resulted in 50 articles. After selection following the established criteria, four cohort studies qualified for the final review analysis. The results showed that chincup therapy decreased SNB angle and increased ANB angle; the total pooled weighted mean difference values (95% confidence interval) were −1.18 (−1.69, −0.67; P < .00001) and 1.90 (0.60, 3.21; P  =  .004), respectively. Two studies showed a increase in Gonial angle (P < .05) but no significant change in the mandibular length (Cd-Gn; P  =  .059 and .39, respectively). One study indicated that chincup therapy exerted no effect on mandibular growth retardation, and mandibular growth continued after the treatment in a downward direction.Conclusion:There are insufficient data in these studies to make clear recommendations regarding the efficacy of chincup therapy in the retardation of mandibular growth.     

骨性安氏Ⅲ类错下颌单颌手术后软硬组织的变化

目的:探讨正畸-正颌联合治疗成人骨性安氏Ⅲ类错,上、下颌软、硬组织的变化及其变化的相关性。方法:选取骨性安氏Ⅲ类错患者20例,手术前、后拍摄X线头颅侧位片,手术方式为双侧下颌骨矢状劈开截骨术(BSSRO)。采用SPSS13.0软件包对数据进行配对t检验。结果:治疗后SNB、B点和Pog点到Y轴的距离变小,ANB变大;软组织颏唇角、TLL点、SB点和TC点到Y轴的距离均变小,且均有显著差异(P<0.01)。SB点到Y轴的距离与B点到Y轴的距离存在线性关系,比值为1∶1,决定系数R2=0.96;TC点到Y轴的距离与Pog点到Y轴的距离比为0.84,决定系数R2=0.97。结论:单纯下颌前突患者经正畸和BSSRO治疗后,上颌软组织无明显变化,上、下唇长度不受影响。颏前点软组织与骨组织变化比值为0.84,颏唇沟点为1:1,相关强度均在0.9以上。