Cephalometric evaluation of anterior open-bite nonextraction treatment, using multiloop edgewise archwire therapy

There are very few reports of extensive and detailed cephalometric investigations of nonextraction treatment changes for patients with anterior open bite. The purpose of this study was to evaluate changes in dentomaxillofacial morphology by way of lateral and oblique cephalograms of patients who had undergone multiloop edgewise archwire (MEAW) therapy for anterior open-bite correction. The subjects consisted of 21 Japanese female patients who received MEAW therapy without premolar extraction. The mean pre- and posttreatment ages were 16 years 9 months and 19 years, respectively. Lateral and oblique cephalograms were taken before and after treatment. Fifteen angular and 29 linear measurements were obtained from the lateral cephalograms; 17 angular and 20 linear measurements were obtained from the oblique cephalograms. Treatment changes were evaluated by the paired t-test. The upward and forward rotational changes of the mandible consequent to the use of the MEAWs and anterior vertical elastics were larger than the downward and backward rotational changes of the mandible, due to the extrusion of the posterior teeth by leveling and alignment. The uprighting and retrusion of the premolars and molars, and the extrusion, uprighting, and/or retrusion of the incisors and canines played important roles in the anterior open-bite nonextraction treatment by dint of the MEAW technique.     

Computer simulation system for orthognathic surgery

Authors– Noguchi N, Goto M Objective – The system aimed to make a simulation model of an orthognathic patient without using his/her computed tomography data. Design – The morphological data of the teeth and face were obtained by laser scanner. All the data were integrated in the reference coordinate system of frontal and lateral cephalograms using projection matching technique. Setting – A case of mandibular prognathism was analyzed and presented. Experimental variable – About 7 mm (left side) to 6 mm (right side) of mandibular setback with a small rotation was performed on this case. Results – Simulated osteotomies and bone movements help us to analyze the movement of bone and soft tissue. Collisions and gaps generated between bone segments and facial changes are shown. Conclusion – This simulation system will be particularly useful for the selection of an optimal operative method in cases in which the change in facial soft tissue shape should be carefully deliberated.     

Association between condylar position, joint morphology and craniofacial morphology in orthodontic patients without temporomandibular joint disorders

The present study investigated condylar position and joint morphology in adolescent patients and elucidated the possible association between the joint structure and condylar position, and craniofacial morphology. Sixty-five adolescent patients were selected as subjects and their tomograms and lateral cephalograms were analysed. No significant differences in joint spaces were found between the right and left temporomandibular joints. Both the condyles in this population were located slight anteriorly in the glenoid fossa. With respect to the association between condylar position, joint morphology and craniofacial morphology, the ramus plane angle also exhibited significant negative correlations with posterior, lateral and medial joint spaces. Furthermore, there was a significant negative correlation between the gonial angle and the anterior joint space. These findings imply that the condyle was likely to show more posterior position in the glenoid fossa when the mandible exhibited clockwise rotation. In conclusion, the condyle in the adolescent subjects showed a symmetrical anterior position relative to the glenoid fossa. In addition, the joint spaces and it ratios were significantly related to the craniofacial morphology associated with vertical dimension. It is suggested that the condylar position may be affected by craniofacial growth pattern.     

上颌快速扩展最佳时机的初步研究

目的:通过患者年龄、牙龄、骨龄,对上颌快速扩展扩弓效应的相关性分析,期望发现应用上颌快速扩展的最佳时机。方法:选择需上颌横向扩展的患者30例,年龄11～14岁,平均12.30岁,进行上颌快速扩展。摄左手腕掌指骨片,扩展矫治前后的上颌前部咬合片、头颅正位定位片。利用SPSS11.0软件包对数据进行t检验、多元线性回归、多元逐步回归分析。结果:年龄相近,扩展效应不一;骨龄与扩展效应具有一定的相关性,偏回归系数为-6.440,P值为0.045;牙龄与扩展效应具有高度相关性,偏回归系数为-1.289,P值为0.000。随着上颌第二恒磨牙的萌出、生长和建牙合,扩展效应明显下降。结论:在上颌第二恒磨牙萌出前进行上颌快速扩展,可在较短的治疗时间内获得所需的骨骼效应。     

恒牙先天缺失患者蝶鞍和颅底的头影测量研究

目的 探究不同程度恒牙先天缺失患者蝶鞍与颅底的大小及形态差异。 方法 选取2020—2021年就诊于四川大学华西口腔医院正畸科的322例患者为研究对象,依据先天缺牙数目将患者分为3组：对照组（无恒牙先天缺失,112例）;试验Ⅰ组（先天缺失1~2颗恒牙,104例）;试验Ⅱ组（先天缺失3颗及以上恒牙,106例）。使用Uceph头影测量软件对每位患者头颅侧位片的蝶鞍的长度、深度和直径以及颅底相关线性和角度参数进行测量。对每位患者的蝶鞍形态进行判定。采用SPSS 21.0软件对数据进行统计学分析。 结果 3组的蝶鞍长度、深度、直径以及颅底相关的线性和角度参数差异均无统计学意义（P>0.05）。3组的鞍桥发生率的差异有统计学意义（P=0.013）,试验组高于对照组（P<0.05）,试验Ⅰ组和试验Ⅱ组差异无统计学意义（P>0.05）。 结论 虽然蝶鞍的线性大小及颅底特征在正常人和先天缺牙患者中未见明显差异,但在先天缺牙患者中鞍桥发生率更高,提示该人群的蝶鞍解剖学形态可能异常。     

Retrospective study on the pharyngeal airspace in the lateral cephalogram - A mathematical model to predict changes due to bimaxillary orthognathic surgery

The aim of this study was the development of a statistical model for reliable prediction of Posterior Airway Space (PAS) changes in lateral cephalograms (LCR) of patients after bimaxillary orthognathic surgery. The LCRs of patients who underwent bimaxillary orthognathic surgery were retrospectively analyzed. The anteroposterior dimension of the PAS was measured at three levels in the pre-operative and postoperative LCR: On the nasopharyngeal (SPAS), oropharyngeal (MAS), and hypopharyngeal level (IAS). The data of 139 patients were collected. The following changes of the PAS were measured: in class II patients SPAS: 0.291 mm (SD = 2.570 mm); MAS: 2.444 mm (SD = 2.986 mm); IAS: 0.750 mm (SD = 3.017 mm); in class III patients SPAS: 1.377 mm (SD 3.212 mm); MAS: 0.962 (SD: = 3.135 mm); IAS: 0.370 mm (SD = 3.468 mm). Linear regression analysis showed for class II patients, a significant influence of mandibular movement on MAS (p = 0.049) and a significant effect of maxillary and mandibular movements on SPAS (p = 0.001) and MAS (p = 0.022) in class III patients. The other jaw displacements had no significant impact on the investigated PAS levels. While the presented method does not permit exact prediction of the dimension of the PAS, it is still an easily accessible method of orientation for the surgeon. The surgeon can initiate three-dimensional examinations to provide exact three-dimensional prediction based on this calculation.     

口外弓颈牵引推磨牙远移的X线头影测量分析

目的：比较口外弓颈牵引推磨牙远移治疗前后的颅面、牙齿的角度变化。方法：调取2002～2005年间完成正畸治疗病例18例作回顾性研究,均为安氏Ⅱ类错低角或均角病例,应用口外弓颈牵引推磨牙远移＋方丝弓矫治技术不拔牙矫治。对治疗前后X线头影测量数据做统计学分析。结果：SNA平均减小1.5°,SNB平均增加0.8°,FMA平均增加1.2°,GoGn-SN平均增加2.2°,治疗前后比较有显著性差异（P〈0.05）。结论：口外弓颈牵引推磨牙远移能有效改善颌骨侧貌,改善低角状况,促使下颌骨顺时针方向旋转。     

Orthodontic Morphological Evaluation of Treacher Collins Syndrome

To establish a treatment for Treacher Collins syndrome, the maxillocraniofacial morphology was quantitatively evaluated by means of cephalometric radiography and the following results were obtained.
1. The cranial base showed a small value of S-ER'(length of sphenoid bone in anterior cranial base), S-SOS'(length of sphenoid bone in posterior cranial base) and S-Ba (length of posterior cranial base) in addition to similarly reduced NSBa, indicating undergrowth of the the cranial base as well.
2. Though the orbit had large BIOD and BIOD/W with ocular hypertelorism, no abnormal finding was obtained in the antero-posterior positioning of the orbit in the skull.
3. In the maxillary region, the maxilla showed undergrowth but no abnormal finding was recorded on the vertical and antero-posterior positioning of the mandible.
4. The mandible showed undergrowth with a wide mandibular angle.
In conclusion, the morphology evaluated quantitatively in patients with Treacher Collins syndrome varied considerably. Therefore, it was considered essential to evaluate the morphology accurately for treating this syndrome including surgery and orthodontic treatment.     

Automatic fusion of lateral cephalograms and digital volume tomography data—perspective for combining two modalities in the future

Objectives:

This article investigates the combination of three-dimensional (3D) digital volume tomography data with two-dimensional (2D) cephalograms in dentomaxillofacial imaging.

Methods:

An automatic hierarchical method to adjust the geometrical relations of these two modalities is presented. The approach is tested on phantom and patient case data, where the feasibility, usability and potential possibilities of the presented innovative method are highlighted. Digitally reconstructed radiographs are computed by casting rays through the 3D volume to get a 2D projection of the volume to produce realistic simulated cephalograms. Different similarity measures are considered based on variations of statistical and deterministic optimization procedures. Stability, precision and accuracy of the method are investigated.

Results:

The presented algorithm demonstrates a reasonable solution of the corresponding 2D/3D registration problem. Exemplary results from phantom and patient case data are presented. Tooth movement could be determined, in contrast to the 2D lateral cephalogram, separated for each side in all three spatial directions.

Conclusions:

Achieved results are highlighted from a clinical point of view and demonstrate the clinical benefit in daily praxis.