西安地区不同骨面型错(牙合)β角测量的研究

目的:对不同骨面型错牙合患者的X线头影测量β角进行研究,为临床应用提供依据。方法:西安地区汉族错牙合患者245例,按照性别、牙龄、骨面型分组,摄X线头颅定位侧位片,测量β角,对性别、牙龄、骨面型的测量结果进行组间t检验,采用ROC曲线进行分析。结果:β角在性别与牙龄组间无显著性差异,但在不同骨面型组间具有显著性差异。Ⅰ类骨面型组β角为34.99°±2.68°。ROC曲线显示β角<31°和β角>39°作为鉴别Ⅱ类骨面型和Ⅲ类骨面型的标准,具有较高敏感度与特异度。结论:西安地区汉族Ⅰ类骨面型人群β角参考值范围为31°~39°。相应β角的余角α角参考值范围为51°~59°。     

ANB角与Wits值评价颌骨矢状不调的研究

目的分析X线头影测量参数ANB角与Wits值在评价安氏Ⅱ类错颌骨矢状位置不调中的差异。方法为84例青少年安氏Ⅱ类与40例安氏Ⅰ类错患者正畸治疗前拍摄X线头颅侧位片,选择与ANB角和Wits值相关的十项头影测量项目,将安氏Ⅱ类错患者分为两组后与安氏Ⅰ类错组进行单因素方差分析。结果ANB角与Wits值在评价安氏Ⅱ类错颌骨矢状位置不调时具有显著性差异;差值较大组,平面较陡,矢状不调更显严重。结论患者颌骨矢状不调较严重且平面较陡者,ANB角与Wits值差异较大,ANB角更能反映其真实性。     

错(牙合)患者β角的临床评价

目的推介一种新的准确评价上下颌骨矢状向关系的头影测量方法:β角.方法β角由A点、B点、髁状突中点三个骨性标志点构成,测量值反应上下颌骨在矢状方向的不调;样本选取137名患者,按照3项标准分三组,分别反应三种错(牙合)类型,并计算均数和标准差.结果安氏Ⅰ类错(牙合)β值为36.42°±3.33,安氏Ⅱ类错(牙合)的β值为26.88°±6.81,安氏Ⅲ类错(牙合)的β值为45.36°±3.68;各组β值在性别上没有显著性差异.结论β角能反应上下颌骨的矢状关系,β值在33°-39°之间为安氏Ⅰ类错(牙合)畸形,安氏Ⅱ类错(牙合)β角较锐,安氏ⅢⅡ类错(牙合)患者的β角较钝.     

A new approach of assessing sagittal discrepancies: the Beta angle.

An accurate anteroposterior measurement of jaw relationships is critically important in orthodontic diagnosis and treatment planning. The angular and linear measurements that have been proposed can be inaccurate because they depend on various factors. The purpose of this study was to establish a new cephalometric measurement, named the Beta angle, to assess the sagittal jaw relationship with accuracy and reproducibility. This angle uses 3 skeletal landmarks-point A, point B, and the apparent axis of the condyle-to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. Seventy-six pretreatment cephalometric radiographs of white patients were selected on the basis of 4 criteria that indicate a normal Class I skeletal pattern; the mean and the SD for the Beta angle were calculated. This group was compared with Class II and Class III skeletal pattern groups. After using the 1-way analysis of variance and the Newman-Keuls test and running receiver-operating-characteristics curves, we obtained results that showed that a patient with a Beta angle between 27 degrees and 35 degrees can be considered to have a Class I skeletal pattern. A more acute Beta angle indicates a Class II skeletal pattern, and a more obtuse Beta angle indicates a Class III skeletal pattern.     

The influence of functional orthodontics and mandibular sagittal split advancement osteotomy on dental and skeletal variables--a comparative cephalometric study

Lateral head films of 200 Class II patients (106 females, 94 males) with a mean pre-treatment age range of 9.9-10.25 years successfully treated with functional orthodontics were analysed before (T1) and after (T2) treatment. The resulting data and findings were compared with lateral head films (T1, T2) of 20 patients (15 females, five males) with a mean pre-treatment age of 25.75 years whose Class II malocclusion and antero-posterior jaw discrepancy had been corrected by a mandibular sagittal split advancement osteotomy. The median and interquartile distances were calculated for every variable, at T1 and T2. The difference between the medians (T2-T1) was analysed using a signed rank test. The changes in scattering (T2-T1) were assessed by means of a F-test. Significant differences regarding the therapeutic influence on skeletal [ANB, Wits, Index, mandibular line-nasal line (ML-NL)], functional (beta', mu), and dental (1-NA degrees , 1-NB degrees ) variables were found. In the group initially treated with functional appliances in order to enhance mandibular prognathism, the antero-posterior (A-P) jaw discrepancy was reduced (ANB, Wits). The vertical skeletal pattern (Index) changed towards a more skeletal open relationship, whereas the ML-NL angle was reduced, which indicates a deepening of the bite. The comparison between biomechanical incisor position analysis (beta', mu) and dental variables (1-NA degrees , 1-NB degrees ) revealed different changes in incisor inclination depending on the type of analysis used. The findings for the dental variables (1-NA degrees , 1-NB degrees ) showed a protrusion of both upper and lower incisors after therapy. The results for the functional variables (beta', mu) showed a retrusion of the upper and a protrusion of the lower incisors. This change in incisor inclination is a dental compensation of the remaining sagittal jaw discrepancy. This effect is most clearly reflected by the functional analysis and the changes of the biomechanical variables beta' and mu. For the orthognathic surgery group, a clear improvement in the dental and skeletal relationship was observed: the skeletal discrepancies in the A-P plane were completely corrected (ANB, Wits) and the inclination of the incisors according to biomechanical and functional aspects was optimized (beta', mu).The alteration in both the Index and ML-NL angle in this group indicated an increase of the open bite components.     

Relationships of sagittal skeletal discrepancy,natural head position,and craniocervical posture in young Chinese children

Objective: The aim of this study was to investigate the relationships of sagittal skeletal discrepancy, natural head position (NHP), and craniocervical posture in young Chinese children with average vertical facial pattern.

Methods: Ninety patients with average Frankfort mandibular plane angle (FH/ML) were classified into skeletal class I, II, and III relationships according to their ANB angle. Cephalometric radiographs in NHP were taken. Variables representing sagittal and vertical craniofacial morphology, head posture, and craniocervical posture were measured and compared.

Results: Subjects in the skeletal class II group showed the largest craniovertical angles and craniocervical angles, while subjects in the skeletal class III group exhibited the smallest craniovertical angles and craniocervical angles, though not all the measurements showed significant differences. The angle formed by the nasion-sella line and the tangent to the posterior border of the mandibular ramus (NSL/RL) was largest in the skeletal class II group and smallest in the skeletal class III group (p?=?0.05).

Discussion: Significant differences exist in NHP and craniocervical posture among skeletal class I, II, and III relationships in young Chinese children. Subjects with skeletal class II relationship tended to exhibit more extended head, and children with skeletal class III relationship often exhibited flexed head.     

Overjet as a predictor of sagittal skeletal relationships

Skeletal relationships in the sagittal plane do not always correspond with dental relationships. The aim of this study was to determine in which type of malocclusion the correlation between overjet and skeletal sagittal parameters assessed by lateral cephalogram analysis is the highest. The extent to which overjet can predict skeletal relationships in the sagittal plane was also assessed. Eighty-three subjects fulfilled the inclusion criteria (40 males and 43 females, mean age 16.3 +/- 4.3 years). Overjet was measured on study casts and sagittal skeletal relationships were analysed on lateral cephalograms. ANB angle, Wits appraisal, and convexity at point A were determined. Mean values and standard deviations of measured parameters were calculated for Class I, Class II division 1, and Class III malocclusion subjects. Correlation between overjet measured on study casts and sagittal skeletal parameters measured on lateral cephalogram was calculated. Overjet as a predictor of skeletal relationships was assessed by means of linear regression analysis. A statistically significant positive correlation (P < 0.01) was found between the values of overjet and ANB (r = 0.690), overjet and Wits appraisal (r = 0.750), and overjet and convexity at point A (r = 0.608) when assessing the whole sample. When linear regression between overjet and cephalometric parameters was assessed separately in Class I, Class II division 1, and Class III malocclusion subjects, the percentage of variability was statistically significant in just four pairs. The findings show that overjet is a good predictor of sagittal relationship only in subjects with a Class II division 1 malocclusion.     

A cephalometric study to investigate the skeletal relationships in patients with increasing severity of hypodontia

Objectives:To determine the skeletal relationships in patients with hypodontia and analyze the effects of severity and pattern.Materials and Methods:Pretreatment lateral cephalograms from 277 patients with hypodontia, categorized by the number of missing teeth as mild (1–2), moderate (3–5), or severe (≥6), were digitized recording angular measurements and ratios and compared with published norms matched for age and gender. Pattern was determined as mandibular, maxillary, bimaxillary, bilateral, anterior, posterior, and anteroposterior. Linear regression models assessed relationships between number of missing teeth and cephalometric parameters, controlling for the pattern of hypodontia.Results:For every additional missing tooth, SNA, SNB, and ANB decreased 0.3°, 0.1°, and 0.2°, respectively; this was clinically significant for >4, >10, and >5 missing teeth, respectively. Mandibular to cranial base ratio decreased 0.3% for every additional missing tooth; this was clinically significant for >10 missing teeth. The MMPA decreased 0.3° for every additional missing tooth; this was clinically significant for >7 missing teeth. Percentage LAFH decreased 0.2% for every additional missing tooth; this was significant for >7 missing teeth. Jarabak ratio increased 0.2% for each additional missing tooth; this was clinically significant for >10 missing teeth. Anterior hypodontia significantly decreased most cephalometric parameters.Conclusions:Patients with hypodontia demonstrated a tendency toward a Class III relationship, caused by decreased maxillary and mandibular angular prognathism and MnCB ratio, though the effect was greater on the maxilla than the mandible. Clinical significance was only associated with severe hypodontia. Vertically, there was a tendency toward decreased MMPA and %LAFH; this was clinically relevant only with severe hypodontia. Anterior hypodontia had a significant effect on skeletal relationship.     

Morphology of the temporomandibular joint in skeletal class iii symmetrical and asymmetrical cases: a study by cephalometric laminography

The aetiology of asymmetric growth in the mandible is not well understood. Previous studies have indicated that the functional lateral shift of the mandible in the period of prepubertal growth may translate to a true skeletal asymmetry, exclusively in skeletal Class III malocclusion. This asymmetry develops more characteristic features during the pubertal and post-pubertal growth periods. Early correction of a functional lateral shift of the mandible is recommended. The purpose of this study was to examine the relationship between the morphology of the temporomandibular joints and asymmetry in skeletal Class III malocclusion in adult female patients. Cephalometric and laminographic findings in 36 asymmetric skeletal Class III patients with a lateral shift of mandible (group 3) were compared to those of 25 symmetric skeletal Class I patients (group 1) and the same number of symmetric skeletal Class III malocclusions (group 2). All the patients had received no orthodontic treatment. The results showed that the TMJ of the side to which the mandible shifted showed a significantly narrower and shorter shape of the condyle head, smaller superior condylar space, and steeper eminence than those of the unshifted side.     

The use of skeletal anchorage in open bite treatment: a cephalometric evaluation

The aims of the present study were to assess the effectiveness of skeletal anchorage for intrusion of maxillary posterior teeth, to correct open bite malocclusion, and to evaluate the usage of titanium miniplates for orthodontic anchorage. Anterior open bite is one of the most difficult malocclusions to treat orthodontically. Currently, surgical impaction of the maxillary posterior segment is considered to be the most effective treatment option in adult patients. Various studies have reported the use of implants as anchorage units at different sites of midfacial bones for orthodontic tooth movement. The zygomatic buttress area could be a valuable anchorage site to achieve intrusion of maxillary posterior teeth. Ten patients, 17 to 23 years old and characterized with an anterior open bite and excessive maxillary posterior growth, were included in this preliminary study. Titanium miniplates were fixed bilaterally to the zygomatic buttress area, and a force was applied bilaterally with nine mm Ni-Ti coil springs between the vertical extension of the miniplate and the first molar buccal tube. The results showed that, with the help of skeletal anchorage, maxillary posterior teeth were intruded effectively. As compared with an osteotomy, this minimally invasive surgical procedure eased treatment and reduced treatment time and did not require headgear wear or anterior box elastics for anterior open bite correction. In conclusion, the zygomatic area was found to be a useful anchorage site for intrusion of the molars in a short period of time.     

Twin-block矫治器治疗早期骨性II类错牙合的X线头影测量分析

目的:分析Twin-block矫治器治疗早期骨性II类错牙合的牙颌形态变化,并探讨其适应证。方法:21例早期骨性II类错牙合患者(5°相似文献   

不同矢状骨面型髁突位置的锥形束CT对比研究

目的 比较骨性Ⅰ类和骨性Ⅱ类受试者的髁突位置,为临床诊断与治疗提供指导。方法 选择50例骨性Ⅰ类受试者（A组,男 27例,女 23例,年龄 18~30岁,平均年龄26岁）和50例骨性Ⅱ类受试者（B组,男 24例,女 26例,年龄 18~28岁,平均年龄 25岁）。两组均拍摄锥形束 CT（CBCT）并应用相应软件进行测量分析,测量髁突位置相关测量项目。所有数据采用 SPSS 19.0统计学软件进行统计分析。结果 A组和 B组双侧髁突位置测量值差异无统计学意义（P>0.05）; A组前后间隙与 B组相比较,差异有统计学意义（P<0.05）; A组前后间隙比较 B组大,差异有统计学意义（P<0.05）。结论 骨性Ⅱ类受试者相对骨性Ⅰ类受试者髁突位置为居中位偏后。     

Effect of rapid maxillary expansion on skeletal, dental, and nasal structures: a postero-anterior cephalometric study

The purpose of this study was to compare the transverse dimensions of skeletal, dental, and nasal structures of a group of patients with maxillary narrowness before and after rapid maxillary expansion (RME) with an untreated control group using postero-anterior (PA) cephalometric radiographs. The material consisted of PA cephalograms of 25 children with a posterior crossbite (mean age 13 years 4 months), and 25 age- and sex-matched controls (mean age 13 years 11 months). Both groups consisted of 20 females and five males. Thirty-four reference points were digitized using the Dentofacial Planner software program. The 17 variables studied consisted of six skeletal, four dental, and seven intra-nasal linear measurements. Student's t-tests were used to compare the differences between the groups, and the effect of RME on skeletal, dental, and nasal structures. RME produced small, but statistically significant changes in maxillary width, upper and lower molar widths, the width between upper central incisor apices, and intra-nasal width. When compared with previous studies, the changes observed were similar for patients of a similar age group, but less than reported for a younger population. There is some evidence that the pattern of expansion produced by RME will vary depending on the age and maturity of the subject.     

Rapid maxillary expansion in growing patients. Hyrax versus transverse sagittal maxillary expander: a cephalometric investigation

The aim of this retrospective study was to cephalometrically evaluate and compare the skeletal and dental effects of a transverse sagittal maxillary expander (TSME) and a Hyrax-type expander (RME) in children with maxillary hypoplasia. Fifty subjects (26 males and 24 females), aged from 6 to 15 years, with a maxillary crossbite caused by basal apical narrowness, were divided into two equal groups. Twenty-five were treated with a TSME and the other 25 with a RME. For each patient, a lateral cephalogram was obtained before treatment (T0) and at the end of the retention period (T1). Changes in the two groups during the observation period were calculated, compared, and statistically analysed with a paired samples t?-test. In the TSME group, SNP-A, I?SN, and I?FH and in the RME group SN-SNP.SNA, N-Me, and U6.PP displayed a statistically significant increase (P < 0.05). The increase in SNP-A, I?SN, and I?FH in the TSME group was significantly greater following treatment than in the RME group. The results support the use of the TSME to produce skeletal changes and dentoalveolar modification and to correct maxillary hypoplasia. It was also demonstrated that in patients with an anterior open bite, the use of the TSME is not contraindicated as the anterior vertical dimension did not increase significantly.     

Treatment of a severe Class III skeletal discrepancy at an appropriate age

The 13-year-old female patient presented for correction of a severe Class III malocclusion with a Class III skeletal pattern. This was considered an appropriate age for treatment as earlier treatment may have been subject to relapse because significant facial growth may have occurred after treatment, and because treatment at a later age may have required orthognathic surgery. Initially, maxillary expansion was provided to widen the maxilla and to free the circum-maxillary sutures. Maxillary protraction headgear was worn to perform sagittal skeletal improvement. Fixed orthodontic appliances were placed to align the dentition and Class III elastics were used to improve intercuspation and stability. Patient cooperation was crucial for success. The skeletal changes provided rewards that included significantly improved facial and dental appearance, while avoiding orthognathic surgery.