北京地区黄种人数字化三维正常(牙合)模型牙冠角度和凸距的测量

目的采用层析法重建30副北京地区黄种人未经正畸治疗的数字化正常(牙合)模型,并测量牙冠倾角、转矩和凸距,为我国直丝弓托槽的研发提供基础.方法利用北京口腔医院正畸科与清华大学共同开发的牙(牙合)模型三维重建系统及测量软件进行重建和测量.结果北京地区黄种人正常(牙合)牙列的特点有:①牙冠倾角:上、下颌切牙、尖牙及上颌第二磨牙的牙冠近中倾斜度较美国人小,尤其以上、下尖牙显著.②牙冠转矩:上颌中、侧切牙的唇向倾斜度较美国人大,而上、下尖牙的舌向倾斜度较小.③牙冠凸距:下颌第一磨牙的牙冠凸距较美国人大.结论我国北京地区黄种人正常(牙合)牙冠倾角、转矩和凸距有显著的自身特点,应当积极地研制和开发基于我国正常(牙合)特点的直丝弓矫治器.     

北京地区黄种人数字化三维正常he模型牙冠角度和凸距的测量

目的 采用层析法重建30副北京地区黄种人未经正畸治疗的数字化正常he模型，并测量牙冠倾角、转矩和凸距，为我国直丝弓托槽的研发提供基础。方法 利用北京口腔医院正畸科与清华大学共同开发的牙he模型三维重建系统及测量软件进行重建和测量。结果 北京地区黄种人正常he牙列的特点有：①牙冠倾角：上、下颌切牙、尖牙及上颌第二磨牙的牙冠近中倾斜度较美国人小，尤其以上、下尖牙显著。②牙冠转矩：上颌中、侧切牙的唇向倾斜度较美国人大，而上、下尖牙的舌向倾斜度较小。③牙冠凸距：下颌第一磨牙的牙冠凸距较美国人大。结论 我国北京地区黄种人正常he牙冠倾角、转矩和凸距有显著的自身特点，应当积极地研制和开发基于我国正常胎特点的直丝弓矫治器。     

中国汉族成人正常（牙合）牙体舌侧形态的测量研究

对中国汉族年轻成人正常（牙合）牙齿的舌侧形态进行三维测量,为研发基于中国人牙体舌侧形态的舌侧直丝弓托槽提供数据参考。方法：采用上海正雅齿科科技有限公司开发的数字化正畸设计系统软件,对普查获得的64副中国汉族正常（牙合）个体的牙齿模型进行三维扫描,并对三维数字模型舌侧面进行计算机定点及测量分析。结果：获得正常（牙合）人群牙齿舌侧的轴倾度、转矩角、冠凸距和尖牙与磨牙补偿角指标的参考值,与国内相关研究结果相近。结论：本研究的测量结果可用于研发中国人舌侧直丝弓托槽标准型。     

不同前牙唇倾度及内收压低步距下隐形矫治器作用的比较：三维有限元研究

目的:应用有限元分析法探究使用隐形矫治器治疗不同前牙唇倾度以及不同内收压低移动步距下,以分步法内收前牙的牙齿移动特点。方法:建立使用隐形矫治器分步法内收上颌前牙的有限元模型,依据中切牙及侧切牙的唇倾度分为工况1:U1-SN=105°、工况2:U1-SN=115°、工况3:U1-SN=125°,牙齿移动总步距为0.2 mm,包括沿牙合平面的内收以及沿牙体长轴方向的压低,每组工况以内收量a:0.18 mm、b:0.14 mm、c:0.10 mm进行分组,分析上述不同情况下的牙齿移动特点。结果:在不同前牙唇倾度以及内收模式下,中切牙、侧切牙均表现为牙冠向舌侧、牙根向唇侧的倾斜移动,第二前磨牙至第二磨牙表现为牙冠向近中的倾斜移动。内收步距越大,前牙冠舌向位移量越大,前牙转矩改变量越大,第二前磨牙至第二磨牙牙冠近中移动量越大。结论:无托槽隐形矫治器在内收前牙时引起前牙的舌倾及伸长、后牙的近中倾斜,其移动量与内收步距呈正比,预设计的前牙绝对压低量无法抵消由牙齿内收引起的相对伸长量。     

牙科锥形束CT评价上颌前牙唇面形态对转矩的影响

目的研究上颌前牙的唇面形态及牙冠牙根成角关系对转矩的影响,为临床治疗中调整牙齿的转矩提供参考。方法选择206颗离体上颌前牙为研究对象,其中中切牙77颗、侧切牙68颗、尖牙61颗。利用牙科锥形束CT将全部牙齿进行扫描,在CT工具软件下进行影像的三维重建并提取全部牙的正中矢状切面图像,利用Auto CAD软件测量图像,分别测量牙冠唇面4个不同高度的切线与牙冠长轴所成的角度,以及牙冠长轴与牙根长轴所成的角度（冠根角）。结果当托槽高度为3.5～5.0 mm时,其高度每变化0.5 mm,上颌中切牙转矩变化约为1.5°,上颌侧切牙和尖牙的转矩变化约为2°。上颌中切牙、侧切牙、尖牙冠根角的均数分别为0.88°、3.87°、-3.30°。结论牙体形态的生物学变化从多方面影响矫治后牙齿的转矩角。     

无托槽隐形矫治拔牙病例的后牙不同轴倾度对牙齿三维力学影响

目的 研究无托槽隐形矫治技术拔除双侧上颌第一前磨牙病例整体内收前牙，后牙不同轴倾度时，各个牙齿的瞬时受力情况。方法 设置4组后牙不同轴倾度的上颌牙列，T1组后牙为正常牙合轴倾度，T2组后牙在T1组基础上后倾5°,T3组后牙在T1组基础上前倾5°,T4组后牙在T1组基础上前倾10°。拔除双侧第一前磨牙，整体内收前牙0.25 mm,在矫治器六轴力传感器测试平台上测量4组牙列中各个牙齿在三维方向的瞬时力。每组牙列设计12副隐形矫治器。结果 与T1组相比，T2组切牙伸长力减小，尖牙远中向力增加，后牙近中向力减小，磨牙颊向和伸长力增大，差异均有统计学意义(P<0.05)。与T1组相比，T3和T4组切牙舌向力和伸长力增大，尖牙远中向力增大，后牙近中向力也增大，磨牙颊向和伸长力增大，差异均有统计学意义(P<0.05)。结论 后牙后倾时利于前牙转矩的表达，有助于保护后牙支抗，但增加了磨牙的颊向力和伸长力。后牙前倾时，前牙更容易出现转矩丢失，覆牙合加深的现象。后牙越前倾，覆牙合越容易加深，后牙支抗容易丢失。     

基于三维冠根整合模型在无托槽隐形矫治中的临床疗效研究

目的 通过建立一种冠根融合的三维模型,评估无托槽隐形矫治器在非拔牙病例中前牙区的临床效果,为临床应用提供指导。方法 收集2020年12月—2021年12月在徐州市口腔医院正畸科就诊患者11例,利用Maestro 3D Dental Studio排牙软件设计矫治方案,获取患者矫治结束预期三维模型,并通过锥形束CT、口内扫描、三维重建软件建立患者术后模型,在Geomagic Studio 2014中进行牙冠与牙根数据的配准,在3-matic中对比治疗后实际模型与治疗前预测模型前牙的转矩与轴倾度的差异。结果 前牙的实际转矩角均小于治疗前的预测角度,其中侧切牙的实现率最高达到了77.55%,中切牙最低为60.70%;前牙的实际轴倾角也同样小于治疗前的预测角度,其中中切牙实现率最高达到了81.49%,尖牙最低为74.95%。结论 基于三维重建及口内扫描技术结合的冠根整合数字化模型,在评估隐形矫治器疗效方面具有优势。在隐形矫治非拔牙病例中,前牙区小范围的移动效率较高。     

上颌骨内横位埋伏阻生尖牙的外科一正畸治疗

目的 :上颌骨内横位埋伏阻生尖牙 ,即尖牙冠位于侧切牙根的近中埋伏阻生尖牙 ,两者有重叠 ,由于上颌尖牙及侧切牙恰位于上颌基骨弓的最大转弯处 ,唇侧骨皮质对尖牙冠唇侧的空间限制 ,若按向尖牙缺隙处方向直接牵引 ,将受到侧切牙牙根的阻挡 ,导致侧切牙牙根的吸收 ,被认为是较难矫治的。本文对此类埋伏阻生尖牙诊断及治疗方法进行了探讨。方法 :用螺旋CT三维显示上颌骨内横位埋伏阻生尖牙 ,确定三个方面的情况 :1)埋伏尖牙冠是位侧切牙根的唇侧还是舌侧 ;2 )埋伏尖牙冠与侧切牙牙根间的距离 ;3)侧切牙牙根是否吸收。用直丝弓矫治器进行间隙预备 ,外科翻瓣暴露埋伏尖牙的牙冠 ,粘贴舌侧扣。用改良Nance弓 (末端带钩 )或带垂直外展曲的不锈钢方丝作牵引装置 ,其牵引点与埋伏尖牙冠的连线能避开邻近侧切牙牙根。根据埋伏尖牙冠与侧切牙之间的位置关系 ,先将尖牙冠向外、向后牵引并绕过邻近侧切牙的牙根 ,然后不断改变牵引方向 ,将埋伏尖牙牵引至其正常位置 ,牵引力约 6 0g。结果 :对 5例 6颗上颌横位埋伏阻生尖牙均导萌出后排齐 ,牙髓和牙周情况良好。结论 :根据螺旋CT诊断 ,采用外科一正畸方法及特殊的牵引装置可有效地矫治横位埋伏上颌尖牙。     

替牙期骨性Ⅲ类患者上前牙牙槽骨形态及其影响因素

目的 评估替牙期骨性Ⅲ类患者上前牙区牙槽骨形态，并探讨其影响因素。方法 选取替牙期骨性Ⅲ类患者48例，基于治疗前的锥体束CT(CBCT)，测量上颌中切牙和侧切牙唇舌侧的牙槽骨厚度和高度，测量牙齿长度、前牙倾斜度、下颌平面角。结果 上颌中切牙舌侧牙槽骨厚度为(3.34±1.33)mm，上颌中切牙唇侧牙槽骨厚度为(1.24±0.51)mm，上颌中切牙舌侧牙槽嵴顶距釉牙骨质距离(1.30±0.89)mm，上颌侧切牙唇侧牙槽嵴顶距釉牙骨质距离(1.68±0.88)mm。上中切牙舌侧牙槽骨厚度、唇侧牙槽骨高度与切牙唇倾度负相关，上切牙唇侧牙槽骨厚度与牙齿长度和下颌平面角负相关。结论 替牙期骨性Ⅲ类患者上切牙唇侧牙槽骨较薄，附着高度较低，舌侧牙槽骨较厚、附着高度较高。上切牙牙槽骨形态与切牙唇倾度、牙齿长度、下颌平面角均有相关性。     

门型个体化唇弓治疗上颌唇向易位阻生尖牙的临床效果研究

目的 探讨门型个体化唇弓对上颌唇向易位阻生尖牙移动的效果和该装置对易位尖牙的移动机制,为临床提供参考。方法 共收集单侧唇向上颌尖牙易位病例8例,用门型个体化唇弓进行矫治。分别于矫治前（T1）和矫治中（T2）易位尖牙牙冠移动至与同象限正常邻牙邻接但偏唇侧位置时拍摄全口曲面断层片,测量牙尖点和根尖点到中线的位移变化及长轴角度变化,进行移动机制的研究。采用牙周探针测量易位尖牙和对侧正常尖牙探诊深度和颊侧临床牙冠高度进行矫治前（T1）、矫治后（T3）牙周变化评估。结果 所有8颗易位尖牙均成功通过门型个体化唇弓移动到牙弓正常近远中位置,平均耗时（11.5±2.7）个月,总的矫治疗程（28.3±4.7）个月。T1～T2期牙尖位移8.1 mm,根尖位移1.5 mm,牙尖位移大于根尖位移（P<0.05）,尖牙长轴发生17.5°倾斜。T1、T3期牙周测量指标探诊深度和颊侧临床牙冠高度测量差异均无统计学意义（P>0.05）。结论 上颌唇向易位阻生尖牙通过门型个体化唇弓在偏唇侧位置移动是可行的和有效的,该装置对易位尖牙的位移方式是控制性倾斜移动。     

Effects of anterior tooth crown inclination on occlusal relationship—A study in three-dimensional reconstruction

ObjectiveThis study aims to analyze the relationship between the central incisor crown inclination and occlusal relationship via three-dimensional study.MethodsTen Chinese volunteers with normal occlusion were selected from physical examination of college students. Lateral cephalograms and CT scans were taken, and the CT data were imported into Simplant pro 11.04 to reconstruct three-dimensional model. In the three-dimensional model, every tooth was separated independently. The upper and lower central incisors were moved labial inclination(up) or lingual inclination(down) and then the upper and lower tooth were aligned based on the central incisor’s position according to the principles of Andrew’s six keys. Four groups were set up with different changes of central incisors. The upper and the lower arch were aligned again based on the moved central incisors. After every motion, the mesio-distal distances of upper and lower canines and first molars were recorded. All data were analyzed using t-test via SPSS19.0, and the significance level was set at 5%.ResultsThe results showed that the mesio-distal distances of occlusal relationship were different from normal occlusal relations, when either upper incisor crown inclination or lower incisor crown inclination was changed, and both upper and lower incisor crown inclination were moved in same or opposite direction. According to the statistical analysis, there was no significant difference when the changes of U1-L1 were no more than 10° (P > 0.05). But there was statistically significant difference (P < 0.05) when changes of U1-L1 were more than 20°.ConclusionsThe incisor crown inclination has influence on the establishment of occlusal relationships. The bigger difference upper and lower incisor crown inclination has, the more deviations from the normal occlusal relationship exist.     

中国人与白种人、日本人正常（牙合）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He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He数据中的轴倾度、转矩和冠凸矩分别与白种人、日本人正常糌数据进行比较分析。结果：中国人正常糌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He数据的直丝弓矫治器时，都应做一定的修改。     

Maxillary incisor angulation and its effect on molar relationships

OBJECTIVES: To determine the variation in molar relationships when upper incisor angulations are altered in a Class I occlusion with normal overjet and overbite. MATERIALS AND METHODS: Typodonts were set up to simulate a Class I occlusion on a normal skeletal base. The lower incisors were positioned normally at 92 degrees to the mandibular plane and the upper incisor angulations were altered from 90 degrees to 130 degrees by 2 degrees increments to the palatal plane. The changes in molar relationships were measured with every 2 degrees of upper incisor angulation change. A regression analysis was performed on the experimental data, and the regression coefficients, slope, and intercept were estimated. RESULTS: A negative linear relationship between upper incisor angulations and change in molar relationship was observed. On average, a change of 20 degrees in upper incisor angulation will alter the molar relationship by 1.8 mm. CONCLUSIONS: Changes in upper incisor angulations are significantly related to change in the molar relationship. Upper incisor angulations that deviate significantly from normal values are likely to result in less than ideal buccal segment relationships.     

Crown angulation measured by laser scanner

The aim of this study was to measure the crown angulation of Japanese subjects with normal occlusion using a laser scanner to minimize human error. Twenty study models with normal occlusion were scanned by laser scanner. Crown angulations of each tooth in scanned 3D dental images were measured according to Andrews’ procedure. In Andrews’ procedure, a plane was established along the mesiodistal contact points of each tooth. The crown angulations of each tooth were measured by projecting the facial axis of the clinical crown (FACC) and a vertical line from the occlusal plane, and the mean and standard deviation were calculated. In maxillary teeth, the canine crown angulation was highest at about 7°, thus indicating a mesial tip, which was seen in all teeth except the second molar. In mandibular teeth, the second molar crown angulation was highest at about 7°, thus indicating a mesial tip, and only the lateral incisor exhibited slight distal tip, while all the remaining teeth exhibited mesial tip. Standard deviations for the maxillary and mandibular teeth ranged from 2.5° to 8°. The standard deviation of the maxillary and mandibular second molars was particularly large.     

头帽肌激动器和普通功能矫治器矫治安氏Ⅱ类1分类错[牙合]上下牙列变化的初步探讨

目的分析头帽肌激动器和普通功能矫治器治疗安氏Ⅱ类1分类错[牙合]患者上下牙列变化,从而进一步探讨功能矫治器治疗Ⅱ类错的作用机理,为临床应用提供理论依据。方法选取Van Beek矫治器治疗安氏Ⅱ类1分类错患者22例（简称VB治疗组）,Twinblock矫治器治疗患者23例（简称TB治疗组）。分别选取性别和骨型对应Van Beek治疗前后患者的未治疗安氏Ⅱ类1分类错[牙合]患者各88例,Twinblock治疗前后对照组患者各92例作为对照组,治疗组和对照组患者分别在治疗前后拍头颅侧位片。结果VB组治疗后,上切牙压低,上切牙突度减少,上切牙唇倾度无改变,上第一磨牙推向后,下前牙唇倾度无变化,下第一磨牙伸长。TB治疗组,上切牙伸长,突度减少,上前牙明显舌倾,上第一磨牙推向后,下前牙唇倾,下第一磨牙伸长。结论Van Beek矫治器能压低上前牙,对上切牙转矩有效控制,能控制下前牙唇倾度。普通功能矫治器治疗安氏Ⅱ类1分类错[牙合]使上前牙舌倾,下前牙唇倾。两类矫治器均能使上牙弓远中移动,但Van Beek矫治器作用更大,且均能使下第一磨牙伸长。     

正常(牙合)青少年替牙期至恒牙初期切牙和磨牙转矩度的纵向观察

目的：研究正常胎青少年从替牙期到恒牙初期切牙和第一恒磨牙转矩度的生长变化，为正畸诊断、治疗方案设计提供依据。方法：对北京大学口腔医学院·口腔医院颅面生长发育中心收集的20名正常胎青少年样本（男性6名，女性14名）替牙期和恒牙初期的牙颌模型进行分析：替牙期：第一恒磨牙及4颗恒切牙萌出至胎平面，研究对象平均（9.5±0.9）岁；恒牙初期：除第三磨牙外其他恒牙均萌出至眙平面，研究对象平均（13．7±1．3）岁。使用BiagginiRayset系统测量切牙和第一恒磨牙的转矩度，分析替牙过程中牙冠倾斜度的变化。结果：替牙期与恒牙初期相比，男、女切牙和磨牙的转矩度差异均无统计学意义（P〉0．05）。替牙期至恒牙初期，上颌中切牙转矩度由14。减小为10.9°（P〈0．001）；下颌中切牙转矩度由1．8°增加为5.2°（P〈0.01）；上颌侧切牙转距度的变化无统计学意义（P〉0．05）；下颌侧切牙转矩度由1．2°增加为3．0°（P〈0．05）。上颌第一恒磨牙转矩度由-6．6°减小为-10．3°（P〈0．001）。下颌第一恒磨牙转矩度由一38．6°增加为-33.2°（P〈0，001）。结论：从替牙期到恒牙初期，上颌第一恒磨牙逐渐舌向直立，下颌第一恒磨牙逐渐颊向直立。     

Objective assessment of occlusal and coronal characteristics of untreated normals: a measurement study.

To determine whether tooth shape and position are constant within tooth types, dental casts of 68 Indians (age range, 10-32 years; mean, 18.72 years) were analyzed. The casts were selected from a larger sample and met the following criteria: Class I molar and canine relationships; overjet and overbite within normal limits; well-related vertical, transverse, and anteroposterior relationships with pleasing profiles and well-aligned arches; and no supernumerary teeth or large restorations. None of the subjects had received orthodontic treatment, and all were in good health and exhibited normal growth. Crown angulation, inclination, offset of maxillary molar, curve of Spee, crown facial prominence, horizontal crown contour, and vertical crown contour were assessed. Means, standard deviations, and standard errors were calculated. The measurements were compared with Andrews's data on 120 nonorthodontic normal occlusion casts. The Student t test was used to determine the significance of differences between the 2 sets of data. It was found that teeth of the same tooth type have similar values of horizontal and vertical crown contours. Values for inclination, angulation, and relative prominence were also similar. Hence, we concluded that tooth shape and position are constant for each tooth type. The data from this study were comparable with Andrews's findings. However, from this study, it would be safe to presume that all teeth except the maxillary second molars require alterations in the bracket base inclination value, and that the maxillary lateral incisor, canine, second premolar, and second molar, and the mandibular canine, require alterations in angulation values.     

Effect of Incisor Angulation on Overjet and Overbite in Class II Camouflage Treatment. A typodont study

OBJECTIVES: To determine the amount of variation in overjet and overbite that may result from changes in upper and lower incisor angulations following upper first premolar extraction treatment in Class II malocclusions. MATERIALS AND METHODS: Typodonts were set up to simulate a skeletal Class II occlusion treated with upper first premolar extractions. The upper incisor angulation was altered through a range from 100 degrees to 120 degrees to the palatal plane by 2 degrees increments. The overjet and overbite were measured with every 2 degrees of upper incisor angulation change. A regression analysis was performed on the experimental data, and the regression coefficients, slope, and intercept were estimated. RESULTS: Excessive proclination of the lower incisors will result in an abnormal overjet and overbite relationship for any magnitude of upper incisor angulation. A normal lower incisor angulation facilitates the attainment of an optimal occlusion. Excessive palatal root torque of the upper incisors will result in an increase in overjet and a consequent decrease in overbite. If the upper incisors are excessively retroclined, an edge-to-edge incisor relationship will result. CONCLUSION: Class II camouflage treatment with upper first premolar extractions requires correctly angulated incisors to achieve optimal buccal segment interdigitation and incisor relationship. Labial root torque and interproximal reduction of the lower anterior teeth should be considered when the lower incisors are excessively proclined.     

Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion

This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.     

直丝弓矫治器矫治完成病例牙 模型牙位的分析

目的评价采用国产Roth直丝弓矫治器矫治完成后的病人是否具有理想的关系及准确的牙齿位置。方法测量分析30付牙模型右侧磨牙关系距离、磨牙补偿角(offsetofmolar)、各个牙齿唇舌向及颊舌向倾斜度(Torque)、牙齿近远中倾斜度(Tip)、旋转度、牙间间隙、Spee氏曲线和牙冠凸度。结果(1)30付牙模型中未有一付完全达到Andrews的六项标准、其中第一恒磨牙关系、牙间隙、Spee氏曲线三项符合率较高、而转矩角、轴倾角旋转度三项则符合率较低。(2)上下前牙轴倾角均大于中国人正常正常值、上下尖牙尤其明显。(3)第一恒磨牙的冠凸度及补偿角明显小于中国人正常值。结论为了更适合中国人,应对国产Roth直丝弓矫治器设计数据进行一些改进。此外,在矫治完成阶段,正畸医生应对弓丝进行必要的艺术及技巧上的处理以达到理想的牙齿位置,但其调整量则远远少于方丝弓矫治器。