Soft tissue profile changes after rapid maxillary expansion with a bonded expander

The aim of this study was to evaluate the short- and long-term treatment effects of rapid maxillary expansion (RME) on the soft tissue facial profile of subjects treated with a modified acrylic-hyrax device. The sample comprised 10 males and 10 females in the mixed dentition. Their average age was 9.3 years ± 10 months pre-treatment (T1), with a narrow maxilla and posterior crossbite, treated with a modified fixed maxillary expander with an occlusal splint. Lateral cephalometric radiographs obtained at T1, immediately post-expansion (T2), and after retention (T3) were used to determine possible changes in the soft tissue facial profile. The means and standard deviations for linear and angular cephalometric measurements were analysed statistically using analysis of variance and Tukey's test (α = 0.05). The measurements at T2 differed significantly from those at T1 and T3. However, RME did not produce any statistically significant alteration (P > 0.05) in the soft tissue profile for any of the cephalometric landmarks evaluated when compared at T1 and T3. The use of a fixed expander associated with an occlusal splint did not cause significant alterations in the soft tissue facial profile at T3. This modified device is effective for preventing the adverse vertical effects of RME such as an increase anterior face height in patients with a crossbite.     

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目的评价上颌前方牵引联合上腭快速扩弓矫治上颌发育不足所致的骨性Ⅲ类错患者面部软组织侧貌的变化。方法选择2007年6月至2009年5月大连医科大学附属第一医院口腔正畸科门诊收治的上颌发育不足所致的骨性Ⅲ类错患者30例(均处于生长发育高峰期或高峰前期),均给予快速扩弓联合前方牵引矫治,测量并比较矫治前后面部软组织侧貌变化。结果前方牵引后,鼻顶点至Y轴距离(Y-Prn)、上唇基角(S-Ns-Sn)、上唇凸距(UL-E)、上唇凸厚(UL-U1)、上唇凹点至Y轴的距离(Y-As)、上唇突点至Y轴的距离(Y-UL)、颏唇角(LL-Bs-Pos)、颏厚度(Pos-Po)、软组织下面高(Sn-Mes)、H角均增大(P<0.01);软组织面角(FH-NsPos)、下唇基角(S-Ns-Bs)、软组织颏前点至Y轴距离(Y-Pos)均减小(P<0.01),鼻唇角(Cm-Sn-UL)亦减小(P<0.05)。结论前方牵引后,上唇显著前移,颏部后下移位,颏唇关系改善,侧貌突度显著增加。     

Determination of Holdaway soft tissue norms for the North Indian population based on panel perception of facial esthetics

IntroductionThe purpose of this study was to determine Holdaway soft tissue norms for the North Indian population based on panel perception of facial esthetics.Material and method90 individuals (45 males and 45 females) from the North Indian population with normal anteroposterior and vertical skeletal relationships on analysis of lateral cephalometric radiographs were selected for the study. The landmarks were located according to the definitions of Holdaway. Ten linear and two angular measurements were analysed on each radiograph. For each variable, the arithmetic mean and standard deviation were calculated. For statistical evaluation, an independent-samples t test was performed.ResultsExcept for the measurements of soft tissue chin thickness, H angle and nose prominence all soft tissue measurements were similar to Holdaway norms. For upper lip thickness, soft tissue chin thickness, skeletal profile convexity and basic upper lip thickness measurements, statistically significant sex differences were determined.ConclusionsBased on this study, new soft tissue norms are established for orthodontic and surgical diagnosis and treatment planning.     

成人骨性Ⅲ类错牙合患者软组织侧貌形态Holdaway分析

［摘要］ 目的 研究成人骨性Ⅲ类错牙合畸形患者的软组织侧貌形态。方法 选取53例（女32例,男21例）成人骨性Ⅲ类患者及53例成人骨性Ⅰ类患者治疗前的CBCT数据,利用Dolphin imaging 11.0软件重建头颅侧位片,采用Holdaway软组织测量方法进行头影测量分析,测量结果按不同性别及不同矢状向骨面型进行比较,用SPSS 20.0软件进行单因素方差分析。结果 成人骨性Ⅲ类患者与骨性Ⅰ类患者相比,骨性Ⅲ类患者的面中1/3凹陷明显（A点突度、Sn-H线）、上唇前突（上唇沟深度、上唇紧张度）、下唇前突（LL-H线）、颏部前突、颏唇沟变浅（软组织面角、H角、颏唇沟深度、颏部厚度）。成人骨性Ⅲ类患者不同性别间的软组织侧貌形态差异主要集中在软组织面角、上唇沟深度及上唇紧张度,其余指标无明显差异,显示出女性患者具有较好的软组织代偿。结论 由于成人骨性Ⅲ类患者上下颌骨间存在明显的矢状向不协调,因此与骨性I类患者相比,其软组织侧貌有着显著不同的特点。     

Analysis of Holdaway soft-tissue measurements in children between 9 and 12 years of age

In this study, 43 lateral cephalometric radiographs from 20 boys and 23 girls subjects were used to determine the Holdaway soft tissue growth changes. Subjects with Class I occlusions, balanced skeletal profiles, normal growth and development, and no orthodontic treatment history were included in the investigation. The cephalometric measurements were carried out on the first and second radiographs of each subject, with an average interval of 5 years. The growth changes in both sexes were analysed separately. The changes resulting from growth and development were determined by a paired t-test. The results showed that all measurements were significant at various levels except for upper lip sulcus depth, subnasal-H line distance, and lower lip H distance in girls, and upper lip sulcus depth, subnasal-H line distance, H angle and lower lip H line distance in boys. The measurement differences were observed with a Student's t-test. No significant difference was found for any measurement except upper lip base thickness (P < 0.001) and upper lip thickness (P < 0.01). The following measurements during the observation period were statistically different: soft-tissue facial angle (P < 0.01 in girls, P < 0.05 boys), nose prominence (P < 0.001 in girls and boys), skeletal profile convexity (P < 0.001 in girls, P < 0.01 in boys), basic upper lip thickness (P < 0.001 in girls and boys), upper lip thickness (P < 0.05 in girls, P < 0.001 in boys), H angle (P < 0.001 in girls), lower lip sulcus depth (P < 0.001 in girls and boys), and soft-tissue chin thickness (P < 0.001 in girls, P < 0.001 in boys).     

Effects of activator and high-pull headgear combination therapy: skeletal, dentoalveolar, and soft tissue profile changes

The aim of this study was to evaluate skeletal, dentoalveolar, and soft tissue profile changes with activator and high-pull headgear combination therapy in patients with Class II malocclusions caused by maxillary prognathism and mandibular retrognathism. The subjects, all in the mixed dentition, were selected from a single centre and were divided into two groups: 28 patients were treated with an incisor double capping activator and a high-pull headgear combination appliance (13 girls, 15 boys mean chronological age 11.7 +/- 1.2 years, skeletal age 12.1 +/- 1.4 years) and an untreated group of 28 subjects (14 girls, 14 boys mean chronological mean age 11.9 +/- 1.1 years, skeletal age 12.3 +/- 1.3 years). The skeletal, dentoalveolar, and soft tissue profile changes that occurred were compared on lateral cephalograms taken before treatment (T0) and after 1.1 +/- 0.3 years when the combination appliance was removed (T1). In the control group, the radiographs were obtained at the start (T0) and after an observation period 1.2 +/- 0.4 years (T1). Statistical analysis was undertaken with Wilcoxon's ranked-sum test for intra-group comparisons and differences between groups with t-test and Bonferroni's test at a level of significance of P < 0.05. Activator and high-pull headgear combination treatment in these growing patients resulted in a correction of the skeletal Class II relationship (ANB -3.4 degrees), a restriction of maxillary growth (SNA -2.0 degrees, OLp-A -2.3 mm), an advancement of the mandibular structures (SNB +2.6 degrees, FH-NPg +2.3 degrees, OLp-B +2.7 mm, OLp-Pg +2.2 mm), an increase in lower face height (ANS-Me +3.9 mm), a correction of the overjet (-5.4 mm), an improvement in overbite (-2.2 mm), uprighting of the maxillary incisors (U1-FH -5.3 degrees, OLp-U1 -2.5 mm), protrusion of the mandibular incisors (IMPA +2.0 degrees, OLp-L1 +2.7 mm), and a correction of the dental Class II malocclusion (OLp-L6 +3.5 mm). The soft tissue profile changes were a correction of facial convexity (G'-Sn-Pg' angle 2.3 degrees, Mlf-Li-x-axis angle 9.1 degrees), and an increase in lower antero-posterior (Mlf-y-axis 5.6 mm, Pg'-y-axis 5.3 mm), and lower vertical (Sls-x-axis 3.8 mm, Pg'-x-axis 3.8 mm, Me'-x-axis 5.1 mm) soft tissue dimensions. The mentolabial fold depth (Mlf-E line) also significantly decreased, -0.8 mm in the treated group. The activator and high-pull headgear combination appliance was effective in treating growing patients with maxillary prognathism, mandibular deficiency, and facial convexity by a combination of skeletal and dentoalveolar changes and improvement in the soft tissue facial profile.     

Three-dimensional soft tissue evaluation after rapid maxillary expansion and mandibular midline distraction osteogenesis

ObjectivesTo evaluate the effects of rapid maxillary expansion (RME) and mandibular midline distraction osteogenesis (MMDO) on facial soft tissues using three-dimensional (3D) images.Materials and MethodsA total of 20 patients (average age 15.86 ± 2.17 years) were treated with RME and MMDO using tooth-borne distractors. Three-dimensional photographs of each patient were taken with a stereophotogrammetry system at baseline (T0), at the end of the distraction period (T1), and at the end of the consolidation period (T2). All data were analyzed using a dependent-samples t-test at a significance level of 5%.ResultsTotal and lower face height increased after MMDO (P < .05). Nasal and mouth width increased after RME as compared with baseline (P < .05). The labiomental angle increased at T1 and decreased at T2 (P < .05). After MMDO, the convexity angle increased while the mandibular angle decreased (P < .05). Upper and lower lip angles increased after RME (P < .05). The distance from the lower lip to the E plane increased after MMDO and decreased after RME (P < .05).ConclusionsThe MMDO and RME procedures provide an efficient nonextraction treatment alternative for transverse maxillomandibular deficiency. MMDO may improve the facial soft tissue profile in the transverse and vertical axis of the mandibular region.     

An orthopaedic approach to the treatment of Class III malocclusions in the early mixed dentition

The aim of this investigation was to study cephalometrically the skeletal, dental and soft tissue modifications induced by a Delaire facemask and Bionator III appliance in a sample of 30 patients (17 boys and 13 girls), aged 4.1-9 years [mean 5.85 years, confidence interval (CI) 5.41-6.29], in the early mixed dentition with a skeletal Class III malocclusion caused by maxillary retrognathism (group 1) and compared with a control sample of 24 subjects (14 boys and 10 girls), aged 4-9 years (mean 5.97 years, CI 5.35-6.58) with untreated Class III malocclusions (group 2). For each patient a lateral cephalogram was taken before treatment (T0), after facemask removal (T1), and at the end of the retention period with a Bionator III (T2). Cephalometric analysis was carried out. The post-treatment cephalometric values in the treated group showed a forward displacement of the maxilla resulting in a statistically significant increase (P < 0.001) in the SNA angle, A-NPg (mm) and PNS-A (mm) linear values. There was a clockwise rotation of the mandible, with a decrease in the SNB angle and a satisfactory correction of the Class III relationship. The beneficial effects on the facial profile were confirmed by an increase in UL-EL distance and in NB--HL and NsPgs--HL angles, and by a decrease in the facial convexity angle. These findings indicate that the Delaire facemask and Bionator III treatment is effective for correcting skeletal Class III malocclusions caused by maxillary retrognathism in the early mixed dentition.     

上颌前牵引联合快速扩弓矫治儿童骨性Ⅲ类错前后软硬组织变化

目的:探讨上颌前牵引联合快速扩弓对儿童骨性Ⅲ类错的矫治效果。方法:对28例儿童骨性Ⅲ类错病人(7～10岁)进行上颌前牵引治疗,在前牵引前快速扩弓1周。分别在治疗开始(T0)和结束(T1)时拍摄头颅定位侧位片,进行定点测量分析。结果:①硬组织变化:ANB角增加5.37°(P<0.05),Wit’s值增加5.74 mm(P<0.05),Ptm-A增加2.49 mm(P<0.05),Yaxis增加1.82°(P<0.05);SNB角减小0.75°(P>0.05),Go-Me、Co-Gn分别增加0.64 mm、2.21 mm,但P>0.05,SN-PP减小0.61°(P>0.05),PP-MP增加5.54°(P<0.05),下面高、下面高/全面高分别增加3.98(P<0.05)、1.61(P>0.05);U1-NA角增加3.10°(P<0.05),L1-NB角减小1.23°(P<0.05),Ms6-PP距增加1.13 mm(P<0.05);②软组织测量项目变化:面型角增大5.98°,颏唇角减小2.45°、H角增大5.2°,上唇-E线距增大1.42 mm,下唇-E线距减小1.18 mm(P<0.05)。结论:前牵引联合快速扩弓矫治儿童骨性Ⅲ类错,可产生显著治疗效果,能促进上颌骨的生长,使面型改善,但下颌出现顺时针旋转,高角病人慎用。     

Evaluation of maxillary protraction and fixed appliance therapy in Class III patients

The aim of this study was to examine the dentofacial changes in Class III patients treated with fixed appliances subsequent to rapid maxillary expansion (RME) and facemask therapy. The material consisted of the cephalograms and hand-wrist films of 14 (9 girls, 5 boys) skeletal Class III and 15 (10 girls, 5 boys) untreated subjects obtained at the beginning of treatment/observation T1, immediately after orthopaedic therapy T2, and at the end of the observation period T3. The mean pre-treatment/control ages were approximately 11.5 years and the observation period was 3 years T2-T1: 1 year, T3-T2: 2 years). The cephalometric films were analysed according to the structural superimposition method of Bj?rk. All tracings were double-digitized and the measurements were calculated by a computer program. Intragroup changes and intergroup differences were statistically analysed. Forward movement of the maxilla (P < 0.01), backward movement and rotation of the mandible, an increase in the ANB angle (P < 0.001), lower face height and overjet (P < 0.001), a decrease of overbite, and an improvement in the sagittal lip relationship (P < 0.01) presented significant intergroup differences between T2 and T1. During the second phase of treatment T3-T2, although not statistically significant, forward movement of the maxilla was less than in the control subjects. Overall changes during the observation period T3-T1 revealed that correction was mainly due to favourable changes in the mandibular and dentoalveolar components of the discrepancy, while these in maxillary position were not different from the control group. The soft tissue profile improved significantly (P < 0.001) in the treatment group. Comparison with the Class I controls at the end of the observation period confirmed that some Class III characteristics still remained in the treated patients.     

面部软组织参考线用于正畸患者侧貌评价的初步研究

目的 探讨面部软组织参考线用于正畸患者侧貌评价的科学性.方法 研究纳入80例骨性Ⅰ类的正畸治疗后患者,其中女性60例,男性20例.收集治疗后侧貌相,由10位经验丰富的正畸医师进行VAS主观评分.同时收集治疗后头颅侧位片进行软组织及上中切牙相关头影测量分析.并进行前额部重叠,测量上中切牙与前额前界线(forehead's...     

Soft Tissue Morphology of Jordanian Adolescents

Objective:To determine soft tissue cephalometric norms of a sample of Jordanian adolescents and to compare them with those of North Americans.Materials and Methods:Forty-one subjects aged 14 to 17 years were selected from a larger random and representative sample of 320 adolescents attending 12 schools in the capital of Jordan, Amman. Seven reference lines were identified and traced according to definitions by Holdaway and Ricketts, and 2 angular and 12 linear measurements were analyzed.Results:Significant differences were found between males and females in measurements of soft tissue facial angle, H angle, subnasale to H line, basic upper lip thickness, upper lip thickness and labrale inferius and superius to E line (P < .05). Males had a more prominent upper lip in relation to the overall soft tissue profile, while the lips of females were considerably more retrusive in relation to the nose and chin. Jordanian norms were similar to those of North Americans, with only two exceptions: the H angle and skeletal convexity which were 5.4 degrees and 3.2 mm greater in Jordanians, respectively.Conclusions:Jordanian soft tissue norms were similar to American norms with the exception of the former having a more prominent upper lip position in relation to the overall soft tissue profile.     

Long-term effects of rapid maxillary expansion: a posteroanterior cephalometric evaluation.

The aim of this study was to investigate long-term effects induced by rapid maxillary expansion (RME), followed by comprehensive orthodontic treatment, in a sample of 42 patients compared with normal growth changes in a sample of 20 subjects. Treated subjects underwent Haas-type RME with 2 turns a day (0.25 mm per turn) until the expansion screw reached 10.5 mm (about 21 days). The Haas expander was kept on the teeth as a passive retainer for an average of about 2 months. Immediately after the Haas expander was removed, fixed standard edgewise appliances were placed. Posteroanterior cephalograms were analyzed for each subject in both groups at T1 (pretreatment) and at T2 (long-term observation). The mean age at T1 was 11 years 10 months for both the treated and the control groups. The mean ages at T2 also were comparable (20 years 6 months for the treated group, and 17 years 8 months for the control group). The study included transverse measurements on dentoalveolar structures, maxillary and mandibular bony bases, and other craniofacial regions (nasal, zygomatic, orbital, and cranial). RME followed by edgewise appliance therapy appears to be an effective procedure to increase transverse facial dimensions in the long term, at both the skeletal and the dentoalveolar levels. Significant pretreatment deficiencies in maxillary width, maxillary incisor apex width, and maxillary first molar width remained corrected at a mean age of about 20 years. The initial deficiency in lateroorbital width was also eliminated.     

Comparison of the effects of Twin Block and activator treatment on the soft tissue profile

The aim of this study was to evaluate and compare the effects of activator and Twin Block (TB) appliances on the soft tissue profile. The study included 50 skeletal Class II patients (25 girls and 25 boys, mean age: 11.9 +/- 0.16 years) who were randomly allocated to one of two functional appliance treatment groups. The control group included 25 untreated skeletal Class II patients (13 boys and 12 girls, mean age: 10.11 +/- 0.91 years). Data were obtained from standardized lateral cephalograms taken at the beginning (T0) and end (T1) of appliance wear. The mean treatment time was 9 months for the activator group and 8 months for the TB group. The observation period of the control group was 8 months. Soft tissue profile changes were evaluated by means of 12 linear and five angular measurements. The groups were compared at T0 and T1 using analysis of variance, and treatment/observation differences (T1-T0) were evaluated with the Kruskal-Wallis test. Treatment changes in both appliance groups differed significantly (P < or = 0.001) from those in the control group, except for Ss-y, Ls-y, Li-E, and A-y measurements in the TB group and Ls-y, Li-E, nasolabial angle, and A-y measurements in the activator group. When the effects of the two appliances were compared, significant differences were observed only for SS-y (P < or = 0.05), Ss-E (P < or = 0.05), Si-E (P < or = 0.05), and nasolabial angle (P < or = 0.01). The effects of the activator and TB appliances on the soft tissue profile were similar; both significantly changed the soft tissue profile.     

上颌快速扩弓联合前方牵引治疗骨性Ⅲ类错牙合畸形对上气道影响的锥形束 CT 分析

目的：研究上颌快速扩弓联合前方牵引治疗骨性Ⅲ类错(牙合)畸形对上气道影响的三维变化。方法：选择53例伴上颌骨横向发育不足的骨性Ⅲ类错(牙合)畸形患者。所有患者先采用 Hyrax 矫治器进行上颌快速扩弓,然后前方牵引矫治。平均扩弓16 d,前方牵引平均5个月。分别于扩弓前（T0）、扩弓结束时（T1）及前方牵引结束时（T2）拍摄锥形束 CT 并进行三维重建和测量。结果：扩弓结束时鼻咽段最小截面积、最小截面积处冠状径和鼻咽段容积显著增大（P ＜0．05）;前方牵引矫治后鼻咽段4项指标与扩弓治疗前相比明显增大（P ＜0．05）。结论：上颌骨快速扩弓联合前方牵引可显著增加鼻咽段上气道容积。     

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。     

Facial soft-tissue changes after rapid maxillary expansion analyzed with 3-dimensional stereophotogrammetry: A randomized,controlled clinical trial

Objective:To evaluate three-dimensional (3-D) soft tissue facial changes following rapid maxillary expansion (RME) and to compare these changes with an untreated control group.Materials and Methods:Patients who need RME as a part of their orthodontic treatment were randomly divided into two groups of 17 patients each. Eligibility criteria included having maxillary transverse deficiency with crossbite, and to be in the normal range according to body mass index. In the first group (mean age  =  13.4 ± 1.2 years), expansion was performed. The second group received no treatment initially and served as untreated control (mean age  =  12.8 ± 1.3 years). Skeletal and soft tissue changes were evaluated using posteroanterior cephalograms and 3-D facial images. The primary outcome of this study was to assess the soft tissue changes. The secondary outcomes were evaluation hard tissue and soft tissue relations. Randomization was done with preprepared random number tables. Blinding was applicable for outcome assessment only. MANOVA, t-test, and correlation analyses were used (P  =  .05).Results:In both groups, there was a general trend of increase for the transverse skeletal measurements, but these increases were more limited in the control group. Alar base width was greater in the treatment group (P  =  .002). Pogonion soft tissue point (P  =  .022) was located more posteriorly in the expansion group compared with the control group.Conclusions:Soft tissue changes between groups were similar, except for the alar base, which became wider in the treatment group. Weak correlations were found between the skeletal and soft tissue changes.     

Skeletal alterations associated with the use of bonded rapid maxillary expansion appliance

Bonded maxillary expansion appliances have been suggested to control increases in the vertical dimension of the face after rapid maxillary expansion (RME). However, there is still no consensus in the literature about its real skeletal effects. The purpose of this prospective study was to evaluate, longitudinally, the vertical and sagittal cephalometric alterations after RME performed with bonded maxillary expansion appliance. The sample consisted of 26 children, with a mean age of 8.7 years (range: 6.9-10.9 years), with posterior skeletal crossbite and indication for RME. After maxillary expansion, the bonded appliance was used as a fixed retention for 3.4 months, being replaced by a removable retention subsequently. The cephalometric study was performed onto lateral radiographs, taken before treatment was started, and again 6.3 months after removing the bonded appliance. Intra-group comparison was made using paired t test. The results showed that there were no significant sagittal skeletal changes at the end of treatment. There was a small vertical skeletal increase in five of the eleven evaluated cephalometric measures. The maxilla displaced downward, but it did not modify the facial growth patterns or the direction of the mandible growth. Under the specific conditions of this research, it may be concluded that RME with acrylic bonded maxillary expansion appliance did promote signifciant vertical or sagittal cephalometric alterations. The vertical changes found with the use of the bonded appliance were small and probably transitory, similar to those occurred with the use of banded expansion appliances.     

唇腭裂继发上颌骨发育不足患者牵引成骨后软组织侧貌变化

目的　比较唇腭裂术后继发上颌骨发育不足患者颅外支架式牵引成骨术 (RigidExternalDistraction ,RED)前后软组织面型及鼻唇部变化 ,评价RED治疗上颌发育不足效果。方法　唇腭裂术后继发上颌骨发育不足患者 2 2名 ,其中男性 14名 ,女性 8名 ,平均年龄为 15 3岁。所有患者在改良高位LeFortⅠ型截骨术基础上行颅外支架式上颌骨牵引成骨术。测量RED前后头颅定位侧位片软组织面型、鼻唇部结构各项指标 ,用配对t检验比较RED术前术后变化。结果　RED前后面凸角、软组织鼻根点至零子午线距离、软组织颏前点至零子午线距离、上唇长度、唇间隙、唇颏比和颏唇沟深度变化具高度显著性差异。鼻唇角RED后增加了 7°。上中切牙露出程度无变化。结论　RED治疗唇腭裂术后继发上颌骨发育不足患者 ,在有效地延长前移上颌骨同时 ,面中下部软组织得到适应性改变 ,使面型更为协调 ,上唇长度得到延长 ,鼻唇角趋向增大。     

Rapid maxillary expansion. Is it better in the mixed or in the permanent dentition?

The aim of this study was to compare the dentoskeletal effects of a modified acrylic-bonded rapid maxillary expansion (RME) device when it is used in the mixed and permanent dentitions. The study group consisted of 51 patients in the mixed and permanent dentition (26 girls and 25 boys) who underwent RME treatment. Group 1 was composed of 34 subjects in the mixed dentition (19 girls and 15 boys; mean age, 9.2 +/- 1.3 years). Group 2 consisted of 17 subjects in the permanent dentition (seven girls and 10 boys; mean age 12.7 +/- 1.2 years). Lateral and frontal cephalograms and upper dental casts were collected before treatment (T1), after treatment (T2), and after retention (T3). Intragroup and intergroup changes were evaluated by paired t-test and Student's t-test, respectively. In both groups after RME, the maxilla moved forward; mandible rotated posteriorly; facial height increased; nasal, maxillary, and maxillary intercanine and first molar widths increased; and the upper molars tipped buccally. Almost all these significant changes were stable at follow-up (T3). When overall (T1 - T3) differences were considered, upper molars tipped more, and the ANB angle increased less in the mixed dentition group compared with the permanent dentition group (P < .01). Within the limits of this study, the results suggest that the orthopedic effects of RME are not as great as expected at early ages, and it might be a better alternative to delay RME to early permanent dentition.