广东汉族青少年上颌第一前磨牙冠根测量值的相关性分析

目的:探讨广东地区12～18岁汉族青少年上颌第一前磨牙的冠根值,并分析测量值的相关性。方法:正畸需要拔除的广东地区汉族青少年上颌第一前磨牙男女各100个,参照王惠芸的研究方法,确定测量指标,采用游标卡尺测量牙齿的全长、冠长、根长、冠、颈和根1/2的近中远中径和颊舌径,并对冠根各测量值进行直线相关和回归分析。结果:冠长、颈近中远中径、颈颊舌径、根1/2近中远中径、根1/2颊舌径的测量值男性大于女性(P﹤0.05)。牙齿全长和冠长、根长呈显著正相关,根长和全长的相关系数大于冠长和全长的相关系数;冠长与根长显著负相关;冠近中远中径、颈近中远中径、根1/2近中远中径相互呈正相关(P﹤0.05);冠颊舌径与颈颊舌径、根1/2颊舌径相互呈显著正相关(P﹤0.05)。长度、近中远中径、颊舌径3类中存在回归关系。结论:冠根各测量值间存在相关关系,可用牙冠测量值预测牙颈部和牙根中的相关值。     

青少年上颌第一前磨牙锥形束 CT 三维成像测量研究

目的研究上颌第一前磨牙的解剖形态,探讨锥形束CT在牙体测量中的应用。方法对成都地区青少年120颗上颌第一前磨牙的锥形束CT图像进行三维重建,根据三维牙体模型进行牙体解剖学指标测量,测量指标有10项,包括:牙齿全长、牙冠长度、牙根长度、牙齿冠根比、牙冠宽度(冠近远中径)、牙颈部宽度(颈近远中径)、牙齿冠宽与颈宽之比(冠、颈近远中径之比)、牙冠厚度(冠颊舌径)、牙颈部厚度(颈颊舌径)、牙齿冠厚与颈厚之比(冠、颈颊舌径之比)。并对测量结果进行统计学分析。结果根据锥形束CT图像可以建立良好的上颌第一前磨牙三维牙体模型,检测者2次测量结果的组内相关系数为0.957(P=0.007)。同性别双侧上颌第一前磨牙各测量指标的差异无统计学意义(P>0.05)。双侧上颌第一前磨牙牙根长度、冠根比、牙冠厚度3项指标的性别间差异无统计学意义(P>0.05),其余指标的性别间差异均有统计学意义(P<0.05)。结论使用锥体束CT进行牙体模型三维重建并测量牙体解剖学指标是可行的。     

上颌第二磨牙的解剖外形研究

目的:了解上颌第二磨牙的解剖外形,为临床工作提供帮助。方法:收集临床上拔出的61颗上颌第二磨牙,测量牙体全长、牙冠近远中径、牙冠颊舌径、牙冠长和牙根长,观察牙根的数目。结果:上颌第二磨牙牙体全长的平均值为(19.46±1.65)mm,牙冠近远中径大于牙冠颊舌径,牙冠长小于牙根长,且全长与牙冠长、牙根长,及牙冠近远中径与颊舌径之间存在着显著相关关系(P<0.05)。3根居多,占49.18%,其次为融合根(47.54%)和变异根(3.28%)。结论:上颌第二磨牙的解剖外形较为复杂。     

上颌第一前磨牙3根1例

患者女，14岁，因正畸需要拔除4个第一前磨牙。在20g/l。利多卡因局麻下顺利拔除24。离体牙检查：牙冠为双尖形，[牙合]面颊舌径大于近中远中径，共有3个牙根。在根长1/2处分为颊，舌2根，而颊根在距根尖1/3处又分为近中颊根和远中颊根。     

上颌第一前磨牙根尖区根管横截面形态的研究

目的 研究上颌第一前磨牙根尖区根管横截面的形态.方法 选择15个上颌第一前磨牙(单根牙11个,双根牙4个),利用Isomet低速金刚砂切片机,在距解剖根尖1、2、3、4、5、6 mm处垂直牙体长轴切割.然后在牙科手术显微镜下,利用Photoshop CS 8.0软件测量各截面根管的颊舌径和近远中径,按标准记录根管横截面的形态.结果 共获得切片111个,根管共138个,其中长椭圆形根管发生率为42.0%.单根管牙的颊舌径大于近远中径,以长椭圆形根管形态为主,其发生率向根尖降低;双根牙的颊根管颊舌径大多小于近远中径,但腭根管颊舌径均大于近远中径,长椭圆形根管发生情况更复杂.结论 上颌第一前磨牙根尖区根管横截面形态复杂,可能影响根管治疗的质量.     

部分回族和蒙古族成人恒牙形态测量

目的:了解我国回族和蒙古族人群恒牙牙体形态特征,为牙体牙髓病的临床治疗提供解剖学资料.方法:分别收集新鲜拔除的348个回族和314个蒙古族成人恒牙,按照已建立的汉族成人恒牙测量的形态学测量标准,对牙齿的冠长、根长、全长、颈宽、近中远中径、颊舌径等进行测量并进行统计学分析.结果:回族成人上颌尖牙及下颌磨牙的冠长、上下颌尖牙及上颌第一磨牙的全长均大于蒙古族(P<0.05),回族成人下颌侧切牙的全长、上颌第一前磨牙的近中远中径和颊舌径、上颌第一磨牙的颈宽均小于蒙古族(P<0.05).回族成人较蒙古族成人下颌第二磨牙的根分叉位置更靠近根尖部(P<0.05).结论:回族、蒙古族与汉族成人恒牙牙齿形态存在差异.     

上颌第一前磨牙根管锥度的研究

目的：研究上颌第一前磨牙的根管锥度。方法：将离体的101个上颌第一前磨牙髓腔作＂颊－舌向＂和＂近－远中向＂X线摄影后输入计算机行图象处理,统计该牙根管全长数值、根管中1／2处颊－舌向直径和近－远中向直径、距根尖端0．5 mm处根管的颊－舌向和近－远中向直径,然后代入公式计算根管的锥度。结果：上颌第一前磨牙根管平均长11．4 mm,根管中段颊－舌径平均宽1．8 mm、近－远中径平均宽0．8 mm,靠近根尖的根管颊－舌径平均宽0．6 mm、近－远中径平均宽0．4 mm;将上述数值代入公式得到该牙根管下段的锥度,在颊－舌象限为0．175,在近－远中象限为0．035。结论：上颌第一前磨牙根管下段并非呈圆锥形空间,而是呈颊－舌径＞近－远中径的扁形腔隙;该牙根管预备之初,选择Profile的I号锉较为适宜。     

双侧上颌第一前磨牙三根1例报告

有报道 ,上颌第一前磨牙 5 4.6%在牙根中部或根尖 1/3处分为颊舌二根 ,43 %为单根牙 ,另有 2 .4%为三根 ,较为罕见。笔者近日在临床上遇见一例双侧上颌第一前磨牙三根病例 ,报告如下 :患者 ,女 ,14岁 ,因正畸需要拔除 4个第一前磨牙。局麻下拔除右上第一前磨牙 ,见该牙于根中部分为颊舌向三根 ,其中颊侧二根 ,自颈缘至根分叉处有沟状凹陷 ,远中面最深 ,颊侧二根间次之。 3d后复诊局麻下拔除左上第一前磨牙 ,见该牙亦为三根 :近中颊侧根、远中颊侧根、腭根。近中颊根与腭根融合 ,远中颊根与另外二根在根尖 1/3处分叉 ,根面凹陷情况同右上第一…     

上颌磨牙近中颊根根管截面形态的研究

目的：研究国人离体上颌第一、二磨牙近中颊根根管的内径和截面形态，为临床进行上颌磨牙根管治疗提供理论参考。方法：收集离体上颌第一磨牙108个，上颌第二磨牙167个。自根管口水平截取近中颊根，包埋。自根尖面开始每隔1mm横切牙根至距根尖6mm处，第7个横切面平近中颊根的根管口水平面。根管显微镜（DOM）下观察、拍摄每个牙根的7个切片的冠面，记录每个冠面含有的根管数，测量各截面各根管的颊舌径和近远中径，并按标准记录根管截面形状。结果：上颌第一磨牙共截取756个切片，均见近中颊根主根管（MB），464个切片中可观察到近中颊根第二根管（MB2）；上颌第二磨牙共截取1169个切片，含MB共1169个，MB2共442个；含MB2的标本数在上颌第一磨牙和第二磨牙分别为96个和90个，占88．89％和53．89％。近中颊根主根管（MB）的颊舌径多大于近远中径，截面形状以扁形和椭圆形多见，但愈近根尖，两径间的差距愈小，即MB愈近根尖，愈趋向成圆形：近中颊根第二根管（MB2）的颊舌径和近远中径间的差距变化不大，截面形状以圆形最多，椭圆形次之，扁形最少。结论：上颌第一、二磨牙近中颊根的根管截面形态复杂，提示临床上需配合有效的清理和成形技术以提高该牙位的根管治疗成功率。     

乳牙髓腔形态的影像学研究

目的:探讨乳牙髓腔形态规律。方法:利用RVG数字成像系统采集乳牙唇(颊)-舌向和近-远向X图像,观察髓腔形态并测量相关数据,将测量结果进行统计学分析。结果:乳前牙髓室和根管在牙颈部相连续,无明显界限,大多数乳前牙唇-舌位片显示根尖1/3段根管随牙根明显向唇侧弯曲并且上颌牙比下颌牙明显。上颌乳切牙根颈、根中1/3冠端处根管的唇舌径小于近远中径,而下颌乳切牙则相反,其差异有统计学意义(P<0.05)。乳尖牙根颈、根中1/3和所有乳前牙根尖1/3冠端处根管的唇舌径和近远中径大小无统计学意义。上乳磨牙髓室关系为:颊舌径>近远中径>髓室高度;下颌乳磨牙髓室关系为:近远中径>颊舌径>髓室高度。结论:本研究获得乳牙的RVG数字成像系统的实验结果可为临床应用提供参考。     

上颌第一磨牙根管弯曲度的实验研究

目的:分析上颌第一磨牙根管弯曲位置、方向及弯曲度。方法:收集80个上颌第一磨牙,在根管中分别插入15#-20#扩大针,拍摄近远中向和颊舌向X线片,用Photoshop6.0软件测量根管弯曲位置、方向和弯曲度。结果:上颌第一磨牙腭侧根管通畅、较直。远中颊侧根管80%在近远中方向、45%在颊舌方向有>5°的明显弯曲,弯曲位置多位于根中1/3,且近远中向弯曲度明显大于颊舌向(P<0.05)。近中颊根颊侧根管在近远中方向、颊舌方向分别有82.5%、77.5%出现>5°的明显弯曲。两个方向上的弯曲度无明显差异(P>0.05)。35%的标本探通了近颊根舌侧根管,其在近远中向、颊舌向出现明显弯曲的比例达91%和83%。结论:上颌第一磨牙四个根管在近远中向、颊舌方向均有不同程度的弯曲,其第二弯曲出现的情况也各不相同。     

上颌第一恒磨牙根管弯曲度初探

目的:分析上颌第一恒磨牙根管弯曲发生情况、弯曲位置、弯曲方向及弯曲程度。方法:收集南京地区80例上颌第一恒磨牙,在根管中分别插入15#~20#扩大针,拍摄近远中向和颊舌向X线片,用Photoshop6.0软件测量分析根管弯曲位置、弯曲方向和弯曲角度。结果:1)上颌第一磨牙腭侧根管通畅、较直。2)远中颊侧根管在近远中方向有80%,颊舌方向有45%出现大于5°的明显弯曲,弯曲位置多位于根中1/3,且近远中向的弯曲明显大于颊舌向(P<0.05)。3)上颌第一恒磨牙近中颊根颊侧根管在近远中方向、颊舌方向分别有82.5%、77.5%出现大于5°的明显弯曲。两个方向上的弯曲程度无明显差异(P>0.05)。4)本研究中有35%的标本探通了近颊根舌侧根管,其在近远中向、颊舌向出现明显弯曲的比例达91%、83%。结论:上颌第一恒磨牙四个根管在近远中方向、颊舌方向均有不同程度的弯曲,其第二弯曲出现的情况也各不相同。     

Micro CT重建牙测量模型替代传统石膏测量模型的可行性研究

目的：探讨用Micro CT重建全牙列三维数字化模型替代传统石膏模型进行牙冠外形测量的可行性。方法：用游标卡尺测量上下颌7-7离体牙牙冠的冠宽、冠厚和冠高,作为基准数据;然后用离体牙翻制出上、下颌全牙列石膏模型,分别用游标卡尺和Micro CT自带软件测量牙冠的宽、厚、高;应用统计分析方法,评价各测量方法的可靠性和准确性。结果：利用Micro CT扫描石膏模型获得了精确的三维数字化模型;每项实验中各组数据间呈高度相关性且无明显差异（P〈0.001）;以离体牙测量结果为标准,Micro CT测量的误差范围为-0.338～0.338mm,石膏模型手工测量的误差范围为-0.408～0.408mm。结论：Micro CT可生成高精度的全牙列数字化模型,便于测量和储存,其牙冠外形的测量精度高于石膏模型。     

Mixed dentition analysis in a Senegalese population: elaboration of prediction tables.

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Three main methods have been used to estimate the mesiodistal crown widths of unerupted canines and premolars: direct measurements on radiographs; calculations from prediction equations and tables; and a combination of radiographic measurements and prediction tables. Because there are clear racial differences in tooth sizes, the objectives of this study were to produce odontometric data, correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and the canine and premolars for each quadrant, and prediction tables with the regression equations, specifically for Senegalese children. Fifty black Senegalese students (25 women, 25 men, mean age 23.50 years) were selected from the University Cheikh Anta Diop in Dakar, Senegal. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars were found to be 0.53 and 0.70, respectively. The standard error of the estimate was better (0.66) for women in the maxilla, and the r(2) values ranged from 0.46 to 0.57 for both sexes. Prediction tables were prepared. The accuracy of the prediction tables should be tested in a larger sample including more ethnic groups.     

Design and implementation of a hybrid genetic algorithm and artificial neural network system for predicting the sizes of unerupted canines and premolars

The aim of this study was to develop a novel hybrid genetic algorithm and artificial neural network (GA-ANN) system for predicting the sizes of unerupted canines and premolars during the mixed dentition period. This study was performed on 106 untreated subjects (52 girls, 54 boys, aged 13-15 years). Data were obtained from dental cast measurements. A hybrid GA-ANN algorithm was developed to find the best reference teeth and the most accurate mapping function. Based on a regression analysis, the strongest correlation was observed between the sum of the mesiodistal widths of the mandibular canines and premolars and the mesiodistal widths of the mandibular first molars and incisors (r = 0.697). In the maxilla, the highest correlation was observed between the sum of the mesiodistal widths of the canines and premolars and the mesiodistal widths of the mandibular first molars and maxillary central incisors (0.742). The hybrid GA-ANN algorithm selected the mandibular first molars and incisors and the maxillary central incisors as the reference teeth for predicting the sum of the mesiodistal widths of the canines and premolars. The prediction error rates and maximum rates of over/underestimation using the hybrid GA-ANN algorithm were smaller than those using linear regression analyses.     

上颌第一乳磨牙临床牙冠的计算机辅助测量

目的:收集华北地区上颌第一乳磨牙形态数据,分析其形态特征.方法:使用3d扫描仪对116名儿童重建上颌第一乳磨牙,使用Creo 2.0测量软件测量牙冠最大近远中径、颊舌径、冠指数、冠面积、冠周径、冠高等.结果:获得了华北地区上颌第一乳磨牙冠周径频数表和各检测项医学参考值范围.最大近远中径、颊舌径、冠面积、颌面周径、最大周...     

上颌第一前磨牙根管颊舌向弯曲情况的研究

目的研究上颌第一前磨牙根管颊舌向的弯曲情况。方法选择100个上颌第一前磨牙为研究对象,开髓并充分暴露根管口后,将1个K型锉插入根管内直至根尖孔处。利用数字成像系统（RVG）拍摄每个牙的近远中向影像,采用Schneider法测量根管的弯曲角度,计算弯曲半径和弯曲部分长度。结果1）100颗上颌第一前磨牙共有176个根管,88个根管存在颊舌向弯曲,其中53个位于根尖1/3;21个根管存在“S”形弯曲,其第一弯曲多见于根中1/3,第二弯曲均见于根尖1/3处。2）颊腭侧根管弯曲情况无统计学差异（P>0.05）,但“S”形根管第二弯曲的弯曲情况更为复杂。3）弯曲角度与弯曲半径无相关关系（r=0.002,P>0.05）,但与弯曲部分长度呈正相关关系（r=0.489,P<0.01）。结论上颌第一前磨牙根管颊舌向弯曲发生率较高,其中“S”形根管的弯曲情况更为复杂。     

Mixed dentition space analysis in a Jordanian population: comparison of two methods

AIMS: To test the reliability of the Moyers charts and the Tanaka and Johnston equations in Jordanians and to derive coefficients of correlation between the combined mesiodistal widths of the four permanent mandibular incisors and the combined widths of the canine and premolars of the maxillary and mandibular quadrants. METHODS: The dental models of the dentition of 130 male and 96 female Jordanian subjects (age range is 14-16 years) with complete permanent dentition were randomly selected. The mesiodistal width of the four permanent mandibular incisors, maxillary and mandibular canines, and premolar teeth were measured using a vernier gauge caliper to the nearest 0.1 mm. The actual teeth measurements were then compared with the predicted values derived from the Tanaka and Johnston equations and Moyers probability tables. Correlation and linear regression analyses were performed between the predicted and actual tooth size for Jordanian children and standard regression equations were developed. RESULTS: Except for the maxillary arch in male subjects, Tanaka and Johnston regression equations underestimated the mesiodistal widths of permanent canines and premolars. On the other hand, there were no statistically significant differences between actual mesiodistal widths of canines and premolars and the predicted widths from Moyers charts at the 65% and 75% level for the lower and upper arches in male subjects and at the 85% level for the upper and lower arches in female subjects. For the newly developed regression equations, the correlation coefficients between the sum of the mandibular four incisors and the sum of the canine and premolars were 0.60 (for lower) and 0.51 (for upper) in male subjects and 0.59 and 0.64, respectively, in female subjects. CONCLUSIONS: (1) Tanaka and Johnston prediction method was not accurate when applied to a Jordanian population. (2) Moyers method for prediction can be used for Jordanian children at different probability levels for male and female subjects.     

Eruption process of the second molar

The second molar is located at the distal of the first molar, and we must be aware of its stage of development when we plan to move the first molar distally. Few researchers have investigated the development of second molars. The purpose of this study was to observe the eruption process of the maxillary and mandibular second molars by using 238 panoramic radiographs. The developmental stages of the second molar were divided into four stages: the whole crown calcified = stage 1; beginning root formation = stage 2; initial formation of the radicular bifurcation = stage 3; and the root length is equal to the crown height = stage 4. The mesiodistal crown width of the first and second molars, axial inclination and eruption rate of the second molar, and the space available for emergence of the second molar at each stage were measured, and the statistical analysis was made to assess the developmental changes. It was learned that the mandibular second molars began to erupt at stage 3 and the maxillary second molars at stage 2. The axial inclination of the mandibular second molars maintained almost the same angle and the maxillary second molars were uprighted gradually from stage 1 to 4. The available space increased significantly from stage 1 to 2 in both second molars. It is suggested that the space available for emergence of the second molar is prepared before stage 2, and then the tooth begins to erupt. As the maxillary second molars, there was further increase in the available space after stage 3. Negative correlation was seen between the mesiodistal crown width of the mandibular second molar and the available space in stage 2. Positive correlation was seen between the mesiodistal crown width of maxillary second molar and the available space in stage 3. It is suggested that greater increase in the space available for emergence of the second molar could be expected in the maxillary dental arch, if the mesiodistal crown width of the second molar required it.