治疗安氏Ⅱ类错牙合畸形功能矫治器的研究进展

长期的科学研究中,在儿童生长发育期采用功能矫治器矫治安氏Ⅱ类错已得到满意的疗效。本文就功能矫治器的分类、适应证、作用机制、特点等做一综述,并介绍一种临床应用证明非常有效的新型功能矫治器。     

小平导配合直丝弓矫治器在安氏Ⅱ类错[牙合]中的应用

目的总结小平导配合直丝弓矫治器在安氏Ⅱ类错[牙合]的临床效果。方法选择安氏Ⅱ类错[牙合]30倒,男17例,女13例,年龄12～14岁．均采用直丝弓固定矫治器,结合上颌小平导打开咬合。矫治前拍摄X线头颅定位僻位片,待咬合打开,后牙有接触时拍阶段头颅定位侧位片。选择头影测量指标22项,对测量结果进行t检验。结果MP—SN、PP—MP、S—Ar—Go三项指标在戴小平导前后差异均有统计学意义,说明下颌平面角增大,并且主要是下颌骨后旋的结果。S—Go、N—Me、ANS—Me在戴用后也有豆著增大。这均有利于改善低角患者的面形。L1-MP（mm）、Overbite（mm）戴小平导后显著减小。而U6-PP（mm）、L6-MP（mm）显著增大,说明下前牙明显压低,上下后牙明显升高。结论小平导配合直丝弓矫治器在安氏Ⅱ类错[牙合]是一种快速有效解除前牙深覆骆的方法。     

下颌第三磨牙与下颌角区骨折关系的研究

目的　研究下颌第三磨牙与下颌角区骨折的关系。方法　收集华西医科大学口腔医学院 1986～ 1995年间下颌骨骨折的住院病历及全景片 ,记录下颌第三磨牙与下颌角区骨折的情况 ,并测量下颌第三磨牙的角度和阻生程度 ,应用统计学方法处理数据。结果　有下颌第三磨牙发生下颌角区骨折是没有下颌第三磨牙发生下颌角区骨折的 3.86倍 ,而且下颌第三磨牙角度越小、阻生程度越大 ,越易发生角区骨折。结论　下颌第三磨牙是下颌角区骨折的危险因素。     

Reproducibility and Angle Independence of Electromechanical Wave Imaging for the Measurement of Electromechanical Activation during Sinus Rhythm in Healthy Humans

Electromechanical wave imaging (EWI) is an ultrasound-based technique that can non-invasively map the transmural electromechanical activation in all four cardiac chambers in vivo. The objective of this study was to determine the reproducibility and angle independence of EWI for the assessment of electromechanical activation during normal sinus rhythm (NSR) in healthy humans. Acquisitions were performed transthoracically at 2000 frames/s on seven healthy human hearts in parasternal long-axis, apical four- and two-chamber views. EWI data was collected twice successively in each view in all subjects, while four successive acquisitions were obtained in one case. Activation maps were generated and compared (i) within the same acquisition across consecutive cardiac cycles; (ii) within same view across successive acquisitions; and (iii) within equivalent left-ventricular regions across different views. EWI was capable of characterizing electromechanical activation during NSR and of reliably obtaining similar patterns of activation. For consecutive heart cycles, the average 2-D correlation coefficient between the two isochrones across the seven subjects was 0.9893, with a mean average activation time fluctuation in LV wall segments across acquisitions of 6.19%. A mean activation time variability of 12% was obtained across different views with a measurement bias of only 3.2 ms. These findings indicate that EWI can map the electromechanical activation during NSR in human hearts in transthoracic echocardiography in vivo and results in reproducible and angle-independent activation maps.     

Study of the first hundred phakic eyes treated by peripheral iridotomy using the N.D. Yag laser

Performing a peripheral iridotomy with a ND Yag laser is a simple and efficient technique, with no side effects, no need for anaesthesia other than local and no surgical opening of the eye, with all the risks it entails. Out of 100 cases, 100% were a success from a technical point of view, and we observed no lesion of the lens which could have caused cataract.This out-patient technique, causing fewer complications than with Argon laser, can be used on any patient, whatever the age and the state of the angle, who has to be treated by peripheral iridotomy.The Neodymium Yag laser (ND: Yag) is a pulsed solid laser (1,2,3,8,29,31). It cuts tissues (photodisruption) by means of a shock-wave produced by optical breakdown (plasma formation). Its effect is different from that of the Argon laser which burns tissues (photocoagulation). The present study, of 100 cases, deals with the use of ND: Yag in peripheral iridotomies.     

Facemask therapy with miniplate implant anchorage in a patient with maxillary hypoplasia

A reverse headgear is thought to be an effective .treatment approach for skeletal class Ⅲ malocclusion with retruded maxilla. Clinical studies have shown that the changes of occlusion are a combination of skeletal and dental changes： forward movement of the maxilla, proclination of the maxillary incisors, clockwise rotation of the mandible, and retroclination of the mandibular incisors. However, the undesirable dental effects, such as excessive mesial movement and extrusion of maxillary molars and labial tipping of maxillary incisors, have been reported. Most of previous studies have demonstrated that the best time for maxillary protraction is early mixed dentition. The skeletal effect decreases and the dental effect increases with age. So there is a need for an absolute stable anchorage for maxillary orthopedics to produce more skeletal change and less dental movement.     

联影可旋转540°机架直线加速器在容积调强放疗计划中的效率优势分析

背景与目的：由于传统加速器机架无法跨过180°,对于肿瘤靠近背侧的患者,常采用拼接弧的方式进行放疗计划设计,虽能提高肿瘤控制率,但会增加机架空转时间,同时也会增加机架与患者碰撞的风险。对比分析联影可旋转540°加速器与传统360°加速器（不跨越180°）在容积弧形旋转调强放疗（volumetric-modulated arc therapy,VMAT）计划执行时的潜在优势。方法：按照不同弧长和任意起始角度,随机生成100个弧,按照机架运动轨迹的特性分别分为A、B两组,其中A组计划（540°机架）为可以跨越180°的弧;B组计划（360°机架）为两段位于180°两侧,由总弧长等于A组的两段弧拼接而成。通过轨迹模拟软件,采用double S velocity模型描述转动轨迹,进行复位情况下的执行效率模拟,并结合临床实际病例对A、B两组进行效率优势分析。结果：A组和B组总执行时间、出束时间接近,差异主要来自机器空转。结合临床实际场景,考虑复位,空转时间与双弧计划比例成正比,节省时间最大值为全双弧计划,节省约32 min。对于临床实际病例,全满弧计划执行时间最多可缩短约85 min。结论：540°机架在执行VMAT计划时,特别是对偏离人体中心的计划,在满足临床剂量分布的同时,可以节省机架空转和复位时间,提高治疗效率,并且能有效地避免机架与患者碰撞的风险。     

Comparison of stepwise vs single-step advancement with the Functional Mandibular Advancer in Class II division 1 treatment

Objective:To compare two groups of subjects at the peak of the pubertal growth period treated with the Functional Mandibular Advancer (FMA; Forestadent, Pforzheim, Germany) appliance using either single-step or stepwise mandibular advancement.Materials and Methods:This study was conducted on 34 Class II division 1 malocclusion subjects at or just before the peak phase of pubertal growth as assessed by hand-wrist radiographs. Subjects were assigned to two groups of mandibular advancement, using matched randomization. Both groups were treated with the FMA. While the mandible was advanced to a super Class I molar relation in the single-step advancement group (SSG), patients in the stepwise mandibular advancement group (SWG) had a 4-mm initial bite advancement and subsequent 2-mm advancements at bimonthly intervals. The material consisted of lateral cephalograms taken before treatment and after 10 months of FMA treatment. Data were analyzed by means paired t-tests and an independent t-test.Results:There were statistically significant changes in SNB, Pg horizontal, ANB, Co-Gn, and Co-Go measurements in both groups (P < .001); these changes were greater in the SWG with the exception of Co-Go (P < .05). While significant differences were found in U1-SN, IMPA, L6 horizontal, overjet, and overbite appraisals in each group (P < .001), these changes were comparable (P > .05).Conclusion:Because of the higher rates of sagittal mandibular skeletal changes, FMA using stepwise advancement of the mandible might be the appliance of choice for treating Class II division 1 malocclusions.