口外弓联合滑动杆与单纯口外弓远移6│6的比较研究

目的　研究口外弓结合滑动杆推上颌第一磨牙远移矫治安氏Ⅱ类错牙合畸形磨牙远移的变化量。方法　 16例患者进行口外弓结合滑动杆与单纯口外弓推上颌第一磨牙远移的同体对照性研究 ,平均治疗 96 .37天 ,通过模型分析确定磨牙的移动量和扭转量。结果　口外弓结合滑动杆治疗侧磨牙均达安氏Ⅰ类关系 ,磨牙远移 3.0 0mm± 1.18mm ,而单纯口外弓治疗侧磨牙远移 0 .84mm± 0 .6 8mm(P <0 .0 1)。结论　口外弓结合滑动杆加速了磨牙远移的速度 ,同时兼有部分下颌磨牙的近中移动 ,加快了纠正磨牙安氏Ⅱ类牙合关系。     

Reliability of a facebow transfer procedure.

The three-dimensional orientation of a maxillary cast mounting from a simulated-kinematic facebow transfer was evaluated in multiple trials among three operators on a single subject. The anterior and posterior anatomic facial reference points were marked on the subject. Each operator performed a separate series of trials to reset the anterior facebow component, the two posterior facebow components, and a control series with no resetting of any facebow components relative to the subject. The x, y, and z coordinates of three reference points on the maxillary cast were determined with a machinist microscope relative to a fixed reference after each facebow transfer. A range of differences between mountings of the maxillary cast were found between trials with all three methods used. These mounting errors were due to setting of the instrument and would be expected in routine clinical use of this instrument.     

Virtual facebow technique using standardized background images

The procedure described provides a novel and accessible virtual facebow transfer based on standardized photographs loaded in the virtual articulator module of a computer-assisted design and computer-assisted manufacturing (CAD-CAM) software program for dental applications. The practical application of the technique in a digital workflow is the correct alignment of the digital maxillary cast to the virtual articulator with respect to the patient’s planes and the skin markings of the condylar axis.     

头帽口外弓在高角型拥挤病例治疗中的应用

目的:评价头帽口外弓高位牵引配合直丝弓矫治技术对中重度牙列拥挤伴高角错牙合畸形的矫治效果。方法:选取18例牙列中重度拥挤伴高角的病人,减数拔除4个前磨牙,应用头帽口外弓高位牵引加强磨牙支抗,并控制磨牙高度,结合固定矫治器进行矫治。结果:18例病人牙列排齐,面型得到保持或有良好改善,磨牙和尖牙关系均达到中性,下颌平面角维持或减小。结论:头帽口外弓在中重度拥挤伴高角错牙合畸形矫治中可起到控制磨牙高度和加强磨牙支抗的作用。     

Recording sagittal condylar angles using a mandibular facebow

summary The aim of this study was to determine the average sagittal condylar inclination angles of dentate subjects using a mandibular facebow with pencil tracing styli, to relate these angles to values assigned to articulators, and to assess the repeatability accuracy of drawing a tangent to a traced curve. The right and left sagittal condylar inclination angles of 103 subjects were recorded using a mandibular facebow with pencil tracing styli which marked a graph card during protrusive excursions. Tangents to the tracings were measured with a protractor allowing assessment of reproducibility. The mean left and right sagittal condylar inclination angles were 32° and 31.5°, respectively, with no significant differences ( P =0.609). Individual right and left measurements within each group showed significant differences ( P = 0.0000). The mean of the tangents drawn through three sagittal condylar angle tracings by 10 operators was 33.3°, and the mean of 10 tangents drawn through the same three tracings by one of the authors was 32.9°, with no significant difference ( P = 0.634). The average sagittal condylar inclination angles found in this study are in agreement with those reported in the literature. In fixed sagittal condylar angle articulators 30° appear to be an appropriate setting. The reproducibility of this method of recording sagittal condylar inclination angles was found to be accurate for the individual operator and between operators.     

A clinical evaluation of a locking orthodontic facebow.

Standard orthodontic facebows may accidentally detach from the appliance buccal tubes at night; this could reduce the effectiveness of extra oral traction and occasionally cause an injury. To try and prevent facebow detachment at night a facebow with a locking mechanism was introduced. This study assessed the ability of 706 consecutively treated patients to learn to wear and use this facebow. The facebows were fitted in 9 different practices supervised by 12 orthodontists. Data from the patients and orthodontists were collected over a 2-year period and covered approximately 166,550 nights. All the orthodontists were able to fit and adjust the facebow; a total of 697 patients successfully used the facebow. Accidental detachment of the facebow at night was reported to be less than 1%. This indicates a significant improvement in the safety of the facebow and should help to improve compliance by increasing the number of hours of wear achieved by the patients.     

Accuracy of a fixed value nasion relator in facebow design.

PURPOSE: This study examined whether a fixed value nasion relator accurately locates the orbitale in a patient population. MATERIALS AND METHODS: The mean value for the vertical distance between soft tissue nasion and orbitale was determined through the analysis of cephalometric radiographs of 114 adult patients. This value was then compared to a facebow design, which uses a fixed value of 25.4 mm. RESULTS: In this study, the mean distance between the orbitale and nasion was found to be 26.8 mm. The values ranged from 15.9 to 39.4 mm with a standard deviation of 3.87 mm. CONCLUSION: The difference between the calculated mean and the 25.4 mm fixed value was less than 2.0 mm and presumed to be clinically irrelevant; however, an accumulation of design errors combined with the variation within the patient population was asserted to be clinically relevant and makes the use of a fixed value nasion relator impractical.     

上颌无牙颌的面弓记录与转移

面弓是辅助将上颌无牙颌石膏模型转移并固定在架正确位置的装置。当面弓将上颌无牙颌模型固定到架上时,它应该准确复现患者进行张闭口运动时上颌颌弓相对于双侧髁突的位置关系。本文详细介绍无牙颌面弓记录与转移的临床标准操作方法,主要内容包括确定参考平面、固定托、利用转移台、固定上颌模型等操作,每一步操作都通过相应的图片进行详细说明。     

Comparison of three facebow/semi-adjustable articulator systems for planning orthognathic surgery

Our aim was to measure the steepness of the occlusal plane produced by three different semi-adjustable articulators: the Dentatus Type ARL, Denar MkII, and the Whipmix Quickmount 8800, and to assess the influence of possible systematic errors in positioning of study casts on articulators that are used to plan orthognathic surgery. Twenty patients (10 skeletal class II, and 10 skeletal class III) who were having pre-surgical orthodontics at Liverpool University Dental Hospital were studied. The measurement of the steepness of the occlusal plane was taken as the angle between the facebow bite-fork and the horizontal arm of the articulator. This was compared with the angle of the maxillary occlusal plane to the Frankfort plane as measured on lateral cephalometry (the gold standard). The Whipmix was closest to the gold standard as it flattened the occlusal plane by only 2 degrees (P<0.05). The results of the Denar and Dentatus differed significantly from those of the cephalogram as they flattened the occlusal plane by 5 degrees and 6. 5 degrees (P<0.01), respectively. Clinicians are encouraged to verify the steepness of the occlusal plane on mounted study casts before the technician makes the model.