Compensation trends of the angulation of first molars:retrospective study of 1403 malocclusion cases

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First,angulation of the upper first molar varied significantly with age and tipped most distally in cases aged,12 years and least distally in cases aged.16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

Changes in the crown angulation and dental arch widths after nonextraction orthodontic treatment: Model analysis of mild crowding with high canines

This study was undertaken to examine which factors contributed to the correction of crowding in two patients who underwent nonextraction orthodontic treatment. A study model analysis was conducted to determine the effects of the orthodontic treatment for crowding with high canines on crown angulation and dental arch width in two patients. The results showed that the crown angulation was significantly increased, indicating distal tipping in the maxillary dental arch. This tendency was most commonly observed in the premolars among the lateral teeth. With respect to the dental arch width, the largest change was evident in the first molar and first premolar regions in cases 1 and 2, respectively. On the basis of these results, up-righting of mesially tipped lateral teeth and expansion of narrow dental arches could prove to be the keys to the success of space regaining or correction of high canines and mild crowding.

The Precise Methods for the Measurement of Collimator Hole Angulation and Center of Rotation of SPECT by Adaptive Quality Control Phantom

The Adaptive Quality Control Phantom (AQCP) is a computer-controlled phantom which positions and moves a radioactive source in the Field of View (FOV) of an imaging nuclear medicine device on a definite path to produce a spatial distribution of gamma rays to perform QC Tests such as the Collimator Hole Angulation (CHA) and the Center of Rotation (COR) of Single Photon Emission Computer Tomography (SPECT). The collimator hole angulation for six collimators was measured using a point source and a computer-controlled cylindrical positioning system. In this method, the displacement of the image of a point source was examined as the AQCP was moving point source vertically away from the collimator face. The results of the high-accuracy measurement method of CHA show that the measurement accuracy for absolute angulation errors is better than ±0.024°. The Root Mean Square (RMS) of CHA for LEHR, LEHS and LEUHR collimators of SMV dual heads camera and LEGP, MEGP and HEGP of GE Millennium MG were evaluated to be 0.290°, 0.292°, 0.208°, 0.154°, 0.220° and 0.202°, respectively. It is to be added in this connection that the evaluated RMS of CHA for LEHR collimator with the distance variation from the collimator’s surface ±1 mm has been varied ±0.04 degree. A new method for the center of rotation assessment by AQCP is introduced and the results of this proposed method as compared with the routine QC test and their differences are discussed in detail. We defined and measured a new parameter called Dynamic Mechanical Error (DME) for applying the gantry motion correction.

Results of the Measurement of the Collimator Hole Angulation for Different Collimators of SPECT with Adaptive Quality Control Phantom

The Adaptive Quality Control Phantom (AQCP) is the computer-controlled phantom which positions and moves a radioactive source in the Field of View (FOV) of an imaging nuclear medicine device on a definite path to produce any spatial distribution of gamma rays to perform the QC Tests such as the Collimator Hole Angulation (CHA) of Single Photon Emission Computer Tomography (SPECT). The collimator hole angulation for seven collimators were measured with the method by using a point source and computer-controlled cylindrical positioning. In this method the displacement of the image of a point source examined as the AQCP move point source vertically away from the collimator face. The results of the high-accuracy measurement method of CHA show that the measurement accuracy for absolute angulation errors is better than ±0.024°. The Root Mean Square (RMS) of CHA for LEHR, LEHS, LEUHR, MEGP-250, MEGP-300, MEGP-360 and HEPH collimators of SMV dual heads camera were measured to be 0.290°, 0.292°, 0.208°, 0.194°, 0.181°, 0.177°, 0.150°, respectively. The Root Mean Square (RMS) of CHA for LEGP, MEGP and HEGP collimators of GE Millennium MG were measured to be 0.154°, 0.220° and 0.202° respectively. It is to be added in this connection that the measured RMS of CHA for LEHR collimator with the distance variation from the collimator’s surface +/– 1 mm has been varied +/– 0.04 degree.

Association between anterior internal fixation systems and post-operative lateral angulation in thoracolumbar fractures

Objective To explore the effects of the anterior internal fixation systems on the post-operative lateral angulation in treatment of thoracolumbar fractures.Methods A retrospective study was done to analyze the 172 patients who had

应用Ilizarov技术在旋转中心穹顶状截骨治疗青少年股骨远端外翻畸形

目的:探讨应用Ilizarov技术在旋转中心穹顶状截骨治疗青少年股骨远端外翻畸形的疗效。方法:采用回顾性研究分析2016年1月至2020年10月收治并获得完整随访的11例股骨远端外翻畸形患者的临床资料,其中男7例,女4例;右侧6例,左侧5例;年龄10~14岁。在股骨远端畸形处找出成角旋转中心(center of roration of angulation,CORA),以CORA为中点,行穹顶状截骨,根据Ilizarov外固定穿针原则安装环形外固定架,截断股骨远端,即时矫正股骨远端目测下外翻畸形,外固定架固定维持。术后根据双下肢负重全长正侧位X线片提示的下肢力线及长度结果,矫正残余畸形及短缩。结果:11例均得到随访,时间13~25个月,带架时间12~17周。末次随访拍摄双下肢负重全长正侧位X线片测量11例双下肢长度均等长,畸形均矫正。采用美国特种外科医院(Hospital Special Surgery,HSS)评分评价膝关节功能,均为优。结论:应用Ilizarov技术在旋转中心穹顶状截骨治疗青少年股骨远端外翻畸形,术中即时矫正目测下股骨外翻畸形,术后根据双下肢负重正侧位片提示的下肢力线及短缩程度,动态调整矫正残余畸形及短缩,损伤小,恢复快。

拔牙矫治对恒牙早期下颌第二磨牙近远中向倾斜度的影响

目的探讨恒牙早期拔牙矫治患者下颌第二磨牙(lower second molar,L2M)近远中向角度自发变化与个体临床特征间的关系,为正畸医生的临床工作提供理论指导。方法经筛选共44例患者88颗下颌第二磨牙的近远中倾斜角度数据纳入本研究。根据治疗前L2M牙冠近远中倾斜角度(L2M初始角度)频数分布直方图,将其分为3组:A组:小角度组,L2M初始角度为0°~17.5°;B组:中角度组,L2M初始角度为17.5°~42.5°;C组:大角度组,L2M初始角度为42.5°~60°;根据L2M是否破龈且暴露大部分牙冠分为已萌组、未萌组。根据下颌平面角大小分为高角、低角、均角。利用CBCT重建全景片测量L2M的近远中倾斜度,分析各分组与L2M近远中倾斜角度变化间的关系。结果小角度组、大角度组、未萌组及高角组治疗后L2M近远中角度变大,而中角度组治疗后角度变小,差异有统计学意义(P<0.05)。已萌组及均角组治疗后L2M近远中角度变化不大,差异无统计学意义(P>0.05)。ANB角、Y轴角及下颌平面角与L2M的初始角度均无相关性。结论大角度、高角患者的L2M在矫治过程中更容易近中倾斜。L2M存在向正常轴倾度靠拢的发展趋势。

尺骨远端掌侧成角与腕尺侧疼痛的相关性研究

目的探讨尺骨远端掌侧成角与腕尺侧疼痛的相关性。方法回顾性分析2016年1月至2017年1月因腕尺侧疼痛就诊于联勤保障部队第九八〇医院的患者64例(观察组),选择同期无腕尺侧疼痛症状志愿者64例作为对照组。2组均拍摄双侧腕关节正侧位X线片,通过测量尺骨远端掌侧成角,研究尺骨远端掌侧成角与腕尺侧疼痛的关系。结果观察组双腕尺骨远端掌侧成角差异无统计学意义(P>0.05);观察组与对照组尺骨远端掌侧成角差异无统计学意义(P>0.05);亚组分析显示,观察组尺骨远端掌侧成角170~175°范围的概率为48.44%,对照组为9.38%,2组差异有统计学意义(P<0.05)。结论尺骨远端掌侧成角可能是腕尺侧疼痛的危险因素之一,且角度越小越容易出现腕尺侧疼痛。

Glycogen content relative to expression of glycogen phosphorylase(GPH) and hexokinase(HK) during the reproductive cycle in the Fujian Oyster, Crassostrea angulata

Glycogen, a polymer of glucose, is an important means of storing energy. It is degraded by glycogen phosphorylase （GPH） and hexokinase （HK）, glycogen phosphorylase, and hexokinase cDNAs （Ca-GPH and Ca- HK, respectively）, which encode the primary enzymes involved in glycogen use, cloned and characterized and used to investigate the regulation of glycogen metabolism at the mRNA level in Crassostrea angulata. Their expression profiles were examined in different tissues and during different reproductive stages. Full-length cDNA of GPHwas 3 078 bp in length with a 2 607 bp open reading frame （ORF） predicted to encode a protein of 868 amino acids （aa）. The full-length HK cDNA was 3 088 bp long, with an ORF of 1 433 bp, predicted to encode a protein of 505 aa. Expression levels of both genes were found to be significantly higher in the gonads and adductor muscle than in the mantle, gill, and visceral mass. They were especially high in the adductor muscle, which suggested that these oysters can use glycogen to produce a readily available supply of glucose to support adductor muscle activity. The regulation of both genes was also found to be correlated with glycogen content via qRT-PCR and in situ hybridization and was dependent upon the stage of the reproductive cycle （initiation, maturation, ripeness）. In this way, it appears that the expression of Ca-GPH and Ca-HK is driven by the reproductive cycle of the oyster, reflecting the central role played by glycogen in energy use and gametogenic development in C. angulata. It is here suggested that Ca- GPH and Ca-HK can be used as useful molecular markers for identifying the stages of glycogen metabolism and reproduction in C. angulata.

Spontaneous healing of complicated crown-root fractures in children:Two case reports

BACKGROUND Complicated crown-root fracture is considered a severe dental trauma and is unlikely to heal without treatment.Usually,dentists have to remove the loose coronal fragment of the fractured tooth and treat the remaining part with multidisciplinary approaches.However,we observed spontaneous healing of fracture in two pediatric cases with a history of complicated crown-root fractures over 4 years ago.CASE SUMMARY In case 1,a 12-year-old boy complained of pain at tooth 11 following an accidental fall 1 d ago.Clinical examination showed a crack line on the crown of tooth 11.Cone beam computed tomography(CBCT)images of tooth 11 showed signs of hard tissue deposition between the fractured fragments.The patient recalled that tooth 11 had struck the floor 1 year ago without seeking any other treatment.In case 2,a 10-year-old girl fell down 1 d ago and wanted to have her teeth examined.Clinical examination showed a fracture line on the crown of tooth 21.CBCT images of tooth 21 also showed signs of hard tissue deposition between the fractured fragments.She also had a history of dental trauma 1 year ago and her tooth 11 received dental treatment by another dentist.According to her periapical radiograph at that time,tooth 21 was fractured 1 year ago and the fracture was overlooked by her dentist.Both of these two cases showed spontaneous healing of complicated crown-root fractures.After over 4 years of follow-up,both fractured teeth showed no signs of abnormality.CONCLUSION These findings may provide new insights and perspectives on the management and treatment of crown-root fractures in children.

不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及周围骨结构的锥形束CT测量

目的:采用锥形束CT测量对不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及其周围骨结构进行分析。方法:采用KaVo 3D eXam CBCT机拍摄获得60名成人骨性Ⅱ类错[牙合]患者(年龄18~30岁)的颅颌面三维影像,根据头颅侧位片中FMA、SN-MP角的大小分为低角组(n=16)、均角组(n=25)、高角组(n=19),对上颌双侧尖牙冠根角、牙槽骨附着高度、牙槽骨厚度等进行测量。结果:3组患者上颌尖牙唇、腭侧牙槽骨附着高度以及唇侧牙槽嵴顶水平牙槽骨厚度差异无统计学意义(P均>0.05)。上颌尖牙根尖水平唇、腭侧及总牙槽骨厚度高角组<均角组<低角组(P均<0.05)。上颌尖牙唇、腭侧旋转移动距离和最大旋转距离高角组<均角组<低角组(P均<0.05)。上颌尖牙冠根角高角组>均角组>低角组(P<0.05)。结论:不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及周围骨结构存在差异,正畸矫治过程中进行牙体移动设计时应多加注意。

上颌第三磨牙阻生深度、磨牙倾斜度与前牙开趋势的关系研究

目的:探讨上颌第三磨牙阻生深度和上颌第一、第二磨牙倾斜度与前牙开之间的关系。方法:本研究选取了125例成年患者,按照上颌第三磨牙的高、中、低位阻生深度分为高位组(43例)、中位组(37例)、低位组(45例);分析头颅侧位定位片、CBCT并测量前牙开相关指标及上颌第一、第二磨牙倾斜度。结果:与中位组及低位组相比,高位组患者的垂直向异常指数值(ODI)较小,且上中切牙倾斜度(U1-SN)、SNB及下面高(ANS-Me)值较大(P<0.05);相关性分析显示,ODI与上颌第三磨牙阻生深度呈负相关关系(P<0.01),SNB、ANS-Me和U1-SN与上颌第三磨牙阻生深度呈正相关关系(P<0.01);与中位组及低位组相比,高位组患者的第一、第二磨牙倾斜度较大,偏近中倾斜(P<0.01);上颌磨牙近中倾斜度与上颌第三磨牙的阻生深度呈正相关关系(P<0.01)。此外,上颌第一磨牙倾斜度(U6)、上颌第二磨牙倾斜度(U7)与ANB、ODI呈负相关关系(P<0.01),与SNB、前后不调指数(APDI)、U1-SN呈正相关关系(P<0.01)。结论:上颌第三磨牙阻生深度和上颌第一、第二磨牙倾斜度与开之间有密切关系,上颌第三磨牙阻生深度越高位,上颌磨牙近中倾斜度越大,且前牙开趋势越明显。

新疆地区人群上颌前牙牙根矢状位置及角度的CBCT分析

目的:通过锥形束计算机断层扫描(Cone-beam computed tomography,CBCT)分析新疆地区成人上颌前牙牙根的矢状位置及各分类的分布情况。方法:回顾性分析100名研究对象上颌中、侧切牙及尖牙的CBCT矢状位图像,根据牙根在牙槽骨中的位置分为颊侧型、中间型及腭侧型,并且测量牙根相对于牙槽骨长轴的角度。结果:大多数上前牙的牙根位于牙槽骨的唇侧(占76.0%),中间型占22.3%,腭侧型最少见,仅占1.7%。其中,中切牙唇侧型占73.0%、中间型占24.0%、腭侧型占3.0%,侧切牙唇侧型占68.0%、中间型占31.0%、腭侧型仅占1.0%,尖牙唇侧型占87.0%、中间型占12.0%、腭侧型仅占1.0%;中切牙、侧切牙及尖牙的牙根矢状角度分别为(8.84±2.62)°,(14.52±3.74)°及(19.39±6.24)°,两两比较差异均有统计学意义(P<0.05);不同牙根位置分型比较中,唇侧型(16.71±4.82)°显著大于中间型(6.36±2.60)°及腭侧型(7.52±6.20)°,差异有统计学意义(P<0.05)。结论:中国新疆地区人群上颌前牙牙根多位于牙槽骨唇侧,唇侧骨壁较薄,唇侧型尖牙的矢状角度最大,中间型尖牙矢状角度最小。

运用CBCT分析角度螺丝通道在上颌切牙区早期及延期种植修复中应用的可行性

目的 通过锥形束CT(cone beam computer tomography,CBCT)数据研究角度螺丝通道(angulated screw channel,ASC)在上颌切牙早期及延期种植修复中应用的可行性。方法 选择114位符合纳入标准的受试者CBCT数据,共119个上颌切牙位点,在Simplant软件中参考对侧同名牙的形态对缺牙区进行虚拟修复体牙冠设计,并在此基础上进行种植体虚拟植入,测量以修复为导向与以牙槽骨骨量为导向虚拟植入种植体之间的夹角,以及以牙槽骨骨量为导向虚拟植入种植体时螺丝通道在理想修复体牙冠上的穿出位置,并记录实现螺丝通道从腭侧穿出时所需ASC的最小角度。结果 在119颗上颌切牙虚拟种植方案中,以修复为导向与以骨量为导向虚拟植入种植体之间存在夹角,且在不同性别、不同牙位之间存在统计学差异,女性的夹角大于男性,中位数分别为10.00°(5.30°~14.15°)和6.80°(3.80°~9.30°),侧切牙的夹角大于中切牙,中位数分别为14.45°(9.80°~19.43°)和6.50°(3.85°~9.75°)。以骨量为导向虚拟植入种植体螺丝通道在理想修复体牙冠不同位置穿出比例在不同性别之间的差异无统计学意义,在中切牙、侧切牙牙位之间的差异存在统计学意义,侧切牙从牙冠唇面加切端穿出的总比例高于中切牙。在119个位点的虚拟种植修复方案中,直螺丝通道螺丝固位、ASC螺丝固位、粘接固位3种种植修复方式的比例分别为16.8%、81.5%和1.7%。结论 上颌切牙早期及延期种植修复中,存在着纠正修复体与牙槽骨方向之间的差异、实现螺丝固位种植修复的需求,绝大多数上颌切牙缺失位点可以通过ASC实现螺丝固位种植修复,侧切牙位对ASC的需求较中切牙位更大。

颈内动脉虹吸部应用解剖与数字减影血管造影对照研究及应用

目的 对 35具成人头颅颈内动脉虹吸部进行血管的走行方向、成角、开口方位的观察 ,与5 0例全脑数字减影血管造影 (DSA)对照分析 ,为指导颅内动脉插管提供解剖学依据。方法 甲醛固定成人头颅标本 35具 ;依次分离 ,充分暴露颈内动脉虹吸部 ,仔细观察和测量颈内动脉虹吸部 ;5 0例全脑血管DSA检查阴性的血管情况作参照分析。结果 颈内动脉虹吸部血管走行成角 ,可分为 3个角度和1个弯度 ,两侧差异无显著性 ,与DSA资料对照分析差异无显著性。结论 颈内动脉虹吸部血管走行角度及开口方向 ,对插管具有重要意义。

正常成人腰椎矢状面曲度改变及其影响因素

目的:测量正常成人腰椎矢状面椎体间成角并探讨其影响因素。方法:自2006年1月～2009年1月,在我院体检中心行体检者共672例,获得完整资料者450例,男235例,女215例,平均年龄43岁,利用专用测量软件测量腰椎相邻节段椎体间成角及腰椎曲度(L1～L5椎体间成角)。根据年龄分为青年组、中年组及老年组,观察相邻椎体间成角与年龄、性别及体重之间的关系。结果:腰椎椎体间成角的平均值为:L1-L2,2.52°;L2-L3,5.33°;L3-L4,8.15°;L4-L5,12.11°;L5-S1,20.14°,L1-L5,24.96°。不同性别及体重指数间腰椎曲度差异无统计学意(P>0.05);不同年龄组之间腰椎曲度差异有统计学意义(P<0.05)。随着年龄的增加,腰椎曲度逐渐变小,但中年组与老年组腰椎曲度差异无显著性(P>0.05)。结论:腰椎曲度随着年龄的增加而逐渐减小,但是中年以后变小的腰椎曲度倾向于稳定。

平行和偏移投照根尖片在确诊上颌第一磨牙近中颊根第二根管中的作用

目的 :探讨X线片检查在确诊上颌第一磨牙近中颊根第二根管 (MB2 )中的作用。方法 :选取临床上需要进行上颌第一磨牙牙髓治疗的患者 5 9例作为实验对象。每个患牙均需拍摄术前X线正位投照片、X线偏移投照片和诊断丝正位、偏移投照片。患牙经根管治疗术后 ,计算MB2的发现率。比较 4种X线投照方法与MB2发生率的相关关系。结果 :5 9例 5 9个患牙中 ,存在MB2的患牙为 2 4个 ,占 40 .7%。X线正位投照片发现根管偏移的占 49.2 % ,X线偏移投照片发现根管偏移的占 5 2 .5 % ,诊断丝正位投照片发现根管偏移的占 44 .1% ,诊断丝偏移投照片发现根管偏移的占 5 5 .9%。统计学分析显示 :X线正位投照片和诊断丝正位投照片中根管偏移比率与MB2发生率无显著性差异 (P >0 .0 5 ) ;应用偏移投照 ,发现二者之间存在显著性差异 (P <0 .0 5 )。结论 :根据不同角度X线片和诊断丝照相 ,分析根管影像偏移程度 ,有助于寻找和确定MB2根管的存在。

中国人与白种人、日本人正常牙齿形态的比较研究

目的 :比较中国人与白种人、日本人正常牙合数据 ,为临床应用直丝弓矫治器提供参考。方法 :选择中国人正常牙合数据中的轴倾度、转矩和冠凸矩分别与白种人、日本人正常牙合数据进行比较分析。结果 :中国人正常牙合牙齿形态与白种人有显著的差异 ,而与日本人大致相似 ,但也有一定差别。结论 :临床使用无论是基于白种人或日本人正常牙合数据的直丝弓矫治器时 。

脑底动脉环应用解剖研究

目的 探讨脑底动脉环的血管走行方向、成角、开口方位及先天变异 ,为指导插管提供解剖学的依据。方法 甲醛固定正常成人脑血管标本 35具 ,其中红色乳胶灌注 10具 ;依次分离充分暴露、仔细观察和测量脑底部血管。结果 脑底动脉环前半部变异较大 ;前交通动脉复合体分为 4型 ;后交通动脉起始位置变异极大 ,主要为C2段后壁。结论 脑底动脉环的血管走行、弯曲角度变异较大 ,充分认识其解剖特点 。

正畸拔除第一前磨牙后第三磨牙倾斜度的变化

目的探讨正畸拔除第一前磨牙对第三磨牙倾斜度的影响。方法选择37例拔牙和32例非拔牙患者,分别在治疗前和治疗后的曲面断层片上测量第三磨牙长轴与!平面的交角以及第二、第三磨牙长轴的交角。用U检验来比较两组患者第三磨牙倾斜度在治疗前后的变化。结果拔牙组和非拔牙组间治疗前后下颌第三磨牙长轴与!平面和第二磨牙长轴交角的差异均具有统计学意义(P<0.05);拔牙组和非拔牙组治疗前后上颌第三磨牙长轴与!平面和第二磨牙交角的差异没有统计学意义(P>0.05)。在拔牙组,治疗后下颌第三磨牙比上颌第三磨牙更直立。结论拔除前磨牙的正畸治疗能够改善第三磨牙的倾斜角度。