基于CBCT对下颌管位置的测量分析

目的：应用CBCT对正常人群下颌管在第二前磨牙及第一、二磨牙根尖处位置的测量,来确定其正常位置关系。方法：测量120例18岁以上正常人群第二前磨牙及第一、二磨牙根尖处位置的3个距离：①下颌管中心（ A）到下颌骨下缘最下点（ B）的距离;②下颌管中心（ A）到与A点在同一水平线的颊侧点（ C）的距离;③下颌管中心（ A）到与A点在同一水平线的舌侧点（ D）的距离。每个距离测量3组,取其平均值。结果：男性第二前磨牙根尖处的下颌骨下缘骨壁最厚,其舌侧骨壁厚于颊侧骨壁。在第一磨牙及第二磨牙处,下颌骨下缘骨壁、舌侧骨壁、颊侧骨壁均增厚,且颊侧骨壁厚于舌侧骨壁;女性测量结果及规律与男性相同,其骨壁厚度略较男性骨壁为薄。结论：利用这3个空间距离来确定正常人下颌管在第二前磨牙及第一、二磨牙根尖处的位置,对正颌手术中下颌骨矢状劈开术,囊肿刮治术,种植术等提供理论依据。     

基于CBCT的下颌后牙区骨内重要解剖结构研究

目的利用锥形束CT（cone beam computed tomography,CBCT）软件分析系统NNTViewer对活体下颌骨三维影像重建测量,研究下颌神经管与邻近解剖结构之间的关系。方法选取100例CBCT影像资料,在下颌骨横截面上测量：①下颌第一前磨牙至同侧第二磨牙各牙牙根中点、根尖与颊舌侧骨壁的距离;②下颌神经管与每个后牙根尖之间及与之相对应的颊舌侧骨壁、牙槽嵴顶和下颌骨下缘的距离。结果下颌第一前磨牙至同侧第二磨牙各牙牙根与颊、舌侧骨壁之间的距离,在牙根中点处分别为1．26—5．02mm、3．74～4．45mm,在根尖处分别为3．85—9．23mm、5．43—7．94mm;下颌第二前磨牙至同侧第二磨牙各牙根尖与下颌神经管之间的距离为5．31～8．19mm。下颌第二前磨牙至同侧第二磨牙各牙根尖下方处的下颌神经管与颊、舌侧骨壁之间的距离分别为3．71～7．62mm、2．91～4．12mm,与牙槽嵴顶之间的距离为17．09-19．22mm,与下颌骨下缘之间的距离为8．22～9．28mm。结论下颌后牙（下颌第三磨牙除外）牙根及下颌神经管与颊侧骨壁之间的距离由前往后逐渐变大。下颌神经管距离第二磨牙远中根最近,距离第一磨牙两根最远;与牙槽嵴顶的距离,在第一磨牙处最大,第二磨牙处最小;与下颌骨下缘的距离,在第二磨牙处最大,第一磨牙近中根处最小。     

正常青年人下颌管全长三维走向及下颌骨形态的锥形束CT测量

目的采用锥形束CT（CBCT）分析正常青年人下颌管在下颌骨内的三维位置以及下颌骨的形态特征,为临床下颌骨手术提供解剖学依据。方法 对29例个别正常进行CBCT扫描,用InVivo 5软件对下颌骨进行三维重建,定位标记点,测量下颌骨形态以及下颌管在其内的三维走行。采用SPSS 17.0软件对测量值进行统计分析。结果 下颌管舌侧骨皮质厚度明显较颊侧骨皮质薄。下颌管到颊侧骨皮质的距离从近中到远中逐渐增加,到舌侧骨皮质、牙槽嵴顶的距离从近中到远中逐渐减小,到下颌下缘的距离在第一磨牙处最小,第二前磨牙处最大。下颌体截面高度、宽度、皮质骨厚度左右侧无统计学差异,从中线至远中,下颌体截面高度、舌侧下1/3皮质骨厚度逐渐减小,上截面宽度、唇/颊侧上1/3皮质骨厚度逐渐增大。部分测量项目性别间有统计学差异。结论下颌管入下颌孔后渐渐远离舌侧而向颊侧靠近,然后又逐渐远离偏向舌侧,但其总体走行还是靠近舌侧。男性下颌骨较女性更坚厚。CBCT能精确地显示下颌神经管的走行及其与周边结构的关系。     

正常人颏孔位置的测量分析

目的 :在锥形束CT冠状面上,通过对200例正常人颏孔位置的测量,来确定颏孔的正常位置。方法 :在200例锥形束CT冠状面上,通过神经管的染色,来确定颏孔的位置;同时测量颏孔中心(A点)到唇侧牙槽嵴顶(B点)的距离,颏孔中心(A点)到唇侧下颌骨下缘与B-A向下连线的交点(C点)的距离,并计算AB/BC、AC/BC的比值。统计颏孔位于在下颌第一、二前磨牙根尖,下颌第二前磨牙根尖及下颌第一磨牙根尖的例数。结果:颏孔位于下颌骨上下缘之间略偏上方;颏孔位于下颌第一、第二前磨牙之间者居多,位于下颌第二前磨牙及下颌第一磨牙根尖部者较少。结论:通过对颏孔正常位置的测量,对临床医生在进行手术操作时保护血管和神经起到一定的指导作用。     

正常人群下颌管的三维定位测量研究

目的：应用CT进行下颌管的三维定位测量研究,为牙种植术等提供临床解剖学依据。方法：对50例正常人下颌骨进行螺旋CT扫描,在预定截面上测量下颌管至颊、舌、牙槽嵴顶以及下颌骨下缘的距离,测量结果采用SPSS13.0软件进行统计学分析。结果：下颌骨左右两侧各组测量结果无显著性差异;下颌管至舌侧骨板的距离比下颌管外缘至颊侧骨板距离小,两者差异有显著性（P〈0.05）;下颌管上缘至牙槽嵴顶的距离较下颌管下缘至下颌骨下缘的距离大,两者差异有显著性（P〈0.05）。结论：下颌管在下颌骨后牙区走行中偏向舌侧骨板,而且距离下颌骨下缘较近。当下颌骨的垂直高度不足时,下颌管的颊舌向位置就十分重要,第二磨牙区种植一般伤及下牙槽神经的风险较小。     

螺旋CT三维成像对下颌神经管走向的研究

目的通过螺旋CT探讨下颌神经管与下颌骨的实际位置关系。方法利用螺旋CT对正常青年人,进行下颌骨的横断面连续薄层扫描,并进行多平面重建后,测量并计算正常人群中下颌神经管在下颌骨中的实际位置及走行方向。结果下颌骨多平面重建的冠状位CT图像能清楚显示下颌神经管的位置及走向。①在垂直方向下颌神经管距下颌骨下缘的距离小于距牙槽嵴顶的距离,在第二磨牙区距离下颌骨下缘最近。②在颊舌方向,颏孔至第一磨牙间,下颌神经管距颊侧骨板的距离小于距舌侧骨板的距离。自第二磨牙向后,下颌神经管距颊侧骨板的距离大于距舌侧骨板的距离。③下颌神经管的走行方向在颊舌方向,下颌神经管总体走行是由舌侧逐渐向颊侧倾斜达颏孔,越近磨牙后区距离舌侧骨板越近,越近颏孔距离颊侧骨板越近。在走行高度上,在第三磨牙区由上向下走行。自第二磨牙开始下颌神经管逐渐由下向上走行达颏孔。结论螺旋CT通过多平面重建后,可以准确测量并计算出下颌神经管在下颌骨中的三维空间位置,利用螺旋CT对下颌神经管的位置和走行进行研究是可行的。     

下颌矢状劈开截骨术相关下颌管空间定位的三维CT研究

目的：应用三维CT影像测量下颌管解剖位置与骨皮质和磨牙的关系,为避免下颌矢状劈开截骨术中损伤下齿槽神经血管提供指导。方法：选择50名正常成人下颌骨三维CT扫描图像,应用AW4．4图像处理软件分别在第二前磨牙,第一、第二磨牙正中,下颌磨牙后区处测量下颌管的解剖位置。结果：通过获得的CT数据研究中国人下颌神经管的解剖位置与骨皮质和磨牙的联系,在第二磨牙区域下颌管距离颊侧骨皮质最远（平均7．82mm,最小4．9mm）。结论：在第二磨牙区域下颌体最厚,对于下颌矢状劈开截骨术的颊侧垂直切口须在下颌第二磨牙区域,这个区域骨质最厚并且下颌管距离颊侧骨皮质最远。对于下颌矢状劈开截骨术颊侧垂直切口的安全深度是4．9mm。     

细长型髁突增生病下颌骨及下颌神经管位置CT形态学研究

目的应用CT进行细长型髁突增生病（HE）下颌骨解剖学及下颌神经管形态学研究,为临床治疗提供参考。方法对19例HE患者进行多层CT扫描,采用Mimics 10.0软件进行三维重建,在不同断面重建图像,进行下颌神经管、下颌孔和骨皮质测量,并与无下颌骨病变的对照组进行比较。结果在第一磨牙中心长轴断面的舌侧、第二磨牙中心长轴的颊侧及上缘、磨牙后区中心至下颌角连线断面的颊侧、上缘及下缘、下颌孔下缘下5 mm处水平位断面的舌侧、前缘及后缘,2组下颌神经管外缘距下颌骨表面距离的差异具有统计学意义（P<0.05）;在第一磨牙颊侧和下缘,2组下颌骨骨皮质厚度的差异具有统计学意义（P<0.05）;2组下颌孔至下颌升支前缘及下颌骨下缘距离的差异具有统计学意义（P<0.05）。结论细长型髁突增生病骨皮质厚度从下颌第一磨牙到下颌升支在各个方向均逐渐减小。与正常颌骨相比,下颌神经管在下颌第二磨牙及磨牙后区偏颊侧并靠上方,下颌孔在升支内侧较靠前并偏低。     

应用Micro CT进行下颌骨骨板厚度的测量研究

目的：运用MicroCT测量下颌骨牙根尖到颊侧骨板的解剖距离。方法：应用Micro CT（Skyscan1072,Antwerpen,Belgium）及cutome软件分析下颌骨三维骨结构。结果：下颌第二磨牙远中根到颊侧骨板的平均距离为8.51mm,近中根距离7.34mm,融合根7.19mm。下颌第一磨牙近中和远中根到颊侧骨板的距离分别为5.18mm和4.09mm。当出现有2个远中根时,远中舌侧根到颊侧骨板的厚度约9.52mm。第一前磨牙和第二前磨牙到颊侧骨板的平均距离分别为3.68mm和3.02mm。前牙牙根到颊侧骨板的距离2.07mm～2.48mm。男性下颌骨颊侧骨板厚度大于女性,差异没有统计学意义（P〉0.05）。结论：Micro CT是一种快速、准确、不损伤样本内部结构的有效的评价方法。牙根尖到下颌颊侧骨板厚度的测量结果可为牙根尖手术和牙种植术提供理论依据。     

跨下牙槽神经种植相关解剖结构的影像学测量及分析研究

目的 通过锥形束CT影像数据测量下颌第二磨牙处下颌神经管位置,分析跨下牙槽神经种植术的理论植入范围,为临床上使用该方法解决下颌后牙区种植骨量不足问题提供理论依据。方法 选取80例下颌第二磨牙缺失且缺牙区垂直骨高度<9 mm的患者CBCT图像,测量该处下颌神经管到颊侧骨皮质、舌侧骨皮质、牙槽嵴顶距离,并模拟跨下牙槽神经种植,测量种植体颊舌向倾斜的角度范围。结果 下颌第二磨牙处下颌神经管到颊侧骨皮质、舌侧骨皮质、牙槽嵴顶的距离分别是(6.913±1.222)、(2.859±0.891)、(7.991±0.783)mm,下颌神经管到颊侧骨皮质距离明显大于到舌侧骨皮质距离。75%的患者可行跨下牙槽神经种植术,模拟植入种植体颊舌向倾斜最小角度为19.360°±7.086°,最大角度为39.462°±6.924°。结论 下颌第二磨牙处下颌神经管明显偏向舌侧,保障了颊侧足够的骨量,多数下颌第二磨牙处无法垂直植入短种植体的患者仍可通过跨下牙槽神经种植术植入常规长度种植体。     

Influence of curing tip distance on composite Knoop hardness values

The purpose of this paper was to study the influence of curing tip distance on Knoop hardness values, at different depths, of two composites, Z100 and Silux Plus. Specimens (5 mm in diameter and 2.5 mm in height) were prepared in a copper mold, covered with mylar strip and polymerized for 40 s, at 3 tip-to-composite surface distances: 0 mm (surface contact), 6 and 12 mm, utilizing an XL 3000 curing unit, with 750 mW/cm2 power. The specimens were then stored at 37 degrees C for 24 h. Knoop hardness values were measured using a microhardness tester, with a load of 50 g for 30 s for each indentation. Four specimens were made for each distance and composite and eighteen indentations were made of each specimen. The results were submitted to analysis of variance and Tukey test at 5% significance level. The results indicated that 1) composite Z100: the larger the curing tip distance in relation to the composite, the lower the Knoop hardness values; 2) Silux Plus: increasing the curing tip distance did not produce a statistically significant difference in the Knoop hardness values; however, at 6 and 12 mm, the deeper layers showed lower Knoop hardness values in relation to the surface; 3) Z100: statistically superior in relation to Silux Plus at all three curing tip distances and at all depths (P < 0.05).     

Radiological analysis of maxillary artery relationships to key bony landmarks in maxillofacial surgery

The maxillary artery (MA) is a key structure at risk of injury in numerous oral and maxillofacial surgical (OMS) procedures. Knowledge of safe distances from this vessel to surgically familiar bony landmarks could improve patient safety and prevent catastrophic haemorrhage. Distances between the MA and bony landmarks on the maxilla and mandible were measured using CT angiograms on 100 patients (200 facial halves). The vertical height of the pterygomaxillary junction (PMJ) was mean (SD) measurement of 16 (3) mm. The MA enters the pterygomaxillary fissure (PMF) a mean (SD) distance of 29 (3) mm from the most inferior point of the PMJ. The mean (SD) shortest distance between the MA and medial surface of the mandible was 2 (2) mm (with the vessel directly contacting the mandible in 17% of cases). The branchpoint (bifurcation of the superficial temporal artery (STA) and MA) was directly in contact with the mandible in 5% of cases. The mean (SD) distances between this bifurcation point and the medial pole of the condyle were 20 (5) mm and 22 (5) mm, respectively. A horizontal plane through the sigmoid notch perpendicular to the posterior border of the mandible is a good approximation of the trajectory of the MA. The branchpoint is usually within 5 mm of this line and inferior in 70% of cases. Surgeons should take note that both the branchpoint and the MA contact the surface of the mandible in a significant number of cases.     

Effect of the vertical and horizontal distances between adjacent implants and between a tooth and an implant on the incidence of interproximal papilla

BACKGROUND: The interproximal dental papilla is considered an essential component of the anterior and posterior regions of the maxilla and mandible. The absence of this structure has esthetic and phonetical consequences and lateral food impaction problems occur with the implant-supported prosthesis. The aims of the present study were to: 1) evaluate the effect of the vertical and horizontal distances between adjacent implants (group 1) and between a tooth and an implant (group 2) on the presence of the interproximal dental papilla; and 2) determine whether the interaction between the vertical and horizontal distances might be associated with the incidence of the papilla. METHODS: In 48 patients, 96 interproximal sites in group 1 and 80 in group 2 were examined. The distance from the base of the contact point to the bone crest (D1), the distance between tooth and implant or between two implants (D2), and the distance from the base of the contact point to the tip of the papilla (D3) were measured. RESULTS: In both groups, when D2 was 3, 3.5, or 4 mm, the papilla was present most of the time (P < 0.05), and when D2 was 2 or 2.5 mm, the papilla was absent 100% of the time (P < 0.05). Further, in group 2, when D1 was between 3 and 5 mm, the papilla was present most of the time (P < 0.05). However, in Group 1, only when D1 was 3.0 mm was the papilla present most of the time (P < 0.05). For both groups, analysis of the interaction between D1 and D2 showed that when D2 was < or = 2.5 mm, the papilla was absent; otherwise, when D2 was > or = 3 mm, there was an interaction between D1 and D2. CONCLUSIONS: We conclude that the ideal distance from the base of the contact point to the bone crest between adjacent implants is 3 mm and, between a tooth and an implant, 3 mm to 5 mm. The ideal lateral spacing between implants and between tooth and implant is 3 mm to 4 mm. Further, there is an interaction between horizontal and vertical distances when the lateral spacing is greater than 3 mm.     

Influence of interimplant distance on gingival papilla formation and bone resorption: clinical-radiographic study in dogs

PURPOSE: The purpose of this study was to evaluate in dogs the area between implants after prosthetic restoration within 5 mm distance between the contact point (CP) between crowns and the bone crest (BC). MATERIALS AND METHODS: The mandibular premolars of 6 dogs were extracted bilaterally. After 12 weeks of healing, each dog received 8 implants. On each side, 2 implants were separated by 2 mm (group 1) and 2 by 3 mm (group 2). After a healing period (3 months), the implants were restored with temporary acrylic resin prostheses and after 4 more weeks, with definitive metallic prostheses. After 8 weeks, the distance between the CP and the papilla (P) was measured. The distance between a line extending from the CP and the gingival height at the distal extension of the prosthesis (DE) was also measured. Digital radiographic images were obtained for evaluation of the CP-BC and BC-P distances and the analysis of bone resorption adjacent to the implant surfaces. RESULTS: The median CP-P distances were 1.75 mm and 1.98 mm for groups 1 and 2, respectively; the median CP-DE distances were 2.60 and 2.69, respectively. The mean CP-BC distances were 5.64 mm and 6.45 mm, for groups 1 and 2, respectively; mean BC-P distances were 3.07 mm and 3.55 mm, respectively. DISCUSSION AND CONCLUSIONS: The differences in distances of 2 and 3 mm between implants did not present significant differences in the formation of papillae or in crestal resorption. The CP-BC distances for prostheses should be different from those of natural teeth because in natural teeth, the biologic width is already present, and in the case of implant-supported prostheses, it will develop following second-stage surgery.     

Accuracy of craniofacial measurements: computed tomography and three-dimensional computed tomography compared with stereolithographic models

In a retrospective study, distance measurements of nine children with craniofacial malformation were analyzed. The accuracy of measurements was compared when measured on a workstation using a 16-slice multidetector spiral computed tomography and on a stereolithographic model. Three different methods of defining distances were investigated: 1) on the stereolithographic plastic models, 14 distances connecting landmarks were identified with a digitizer (Polaris Tracker); 2) the same distances were defined at axial, coronal, and sagittal reformats of the computed tomography data set and measured using a Philips MX View workstation; and 3) the same 14 distances were defined at three-dimensional virtual reality models of the skulls at the same workstation. All measurements were performed with all three methods by three different readers. The following conclusions could be drawn: stereolithographic models provide a highly exact reproduction of the skull in children with craniofacial malformations. They are a reliable basis for all analytic and probatory endeavors preparing complicated surgical corrections. Three-dimensional virtual reality display modes serve significantly better for exact distance measurements on the complex surface of the human skull than planar reformats of the same computed tomography data sets.     

种植体支抗后牵引上颌骨颅颌面结构变化的动物实验研究

目的评价种植体支抗后牵引上颌骨对颅颌面的矫形作用。方法生长发育期恒河猴4只，3只用于研究（1只牵引1．5月、2只牵引3月），1只作为对照；采用颧骨微钛板种植体支抗后牵引上颌骨，铸造固位夹板粘接于上颌第一恒磨牙、第二乳磨牙及切牙上，牵引力值每侧1．47N（150克），方向与（牙合）平面平行；对实验前后X线头影测量进行对比分析。结果实验动物A点后移，1．5月组1mm，3月组平均2．5mm；SNA减小，1．5月组1°，3月组平均3．5°。1．5月组前牙覆盖减小3．5mm，其中骨效应大于牙齿效应（2．5：1）；磨牙关系改变为3mm，骨效应大于牙齿效应（5：1）；上颌效应大于下颌效应（2．5：1）。3月组平均前牙覆盖减小6．25mm，其中骨效应大于牙齿效应（1．8：1）；磨牙关系改变为5mm，骨效应大于牙齿效应（4：1）；上颌的作用大于下颌（5．7：1）。结论颧骨微钛板种植体能够提供稳定的支抗后牵引上颌骨，不仅抑制上颌骨向前生长，而且使上颌骨向远中移动，同时伴有逆时针方向的旋转。     

Evaluation of Hard and Soft Tissue Dimensions Around Zirconium Oxide Implant–Supported Crowns: A 1‐Year Retrospective Study

Background: This study aims to evaluate the effect of the distance between the alveolar crest of a full‐ceramic implant to the lowest point of the contact area of the crowns on the interdental papilla. Therefore, the authors proposed a new concept of linear measurements for the reproducible and metric evaluation of distances relevant for the assessment of hard and soft tissue changes around dental implants. Methods: A total of 216 sites were examined in 87 patients. In a radiographic and clinical evaluation, four relevant distances were evaluated. In the x‐ray image, the tip of the papilla was marked with a radiodense mixture of tungsten powder and temporary cement. In a clinical photograph, the lowest point of the interdental contact zone of the crowns was visualized by a metallic interdental ligature. Results: Using the proposed measuring methodology, four different papilla‐deficit situations around ceramic implants could be reproducibly distinguished. When the measurement from the bone crest at the implant was ≤5 mm, the papilla was completely present in 100% of cases. When this distance was 10 mm, the papilla was still present in 67% of the cases, without any cosmetically apparent deficit. Conclusions: A close relationship is observed between the distance from the contact point to the bone and the presence of the papilla. Using a combination of radiographically and clinically visible landmarks allows the reproducible measurement of these distances.     

Three-dimensional facial imaging: accuracy and considerations for clinical applications in orthodontics

This study determined the accuracy of a camera system capable of recording three-dimensional facial images. A Rainbow 3D Camera Model 250 system (Genex Technologies Inc, Kensington, Md) was used to capture images of specific models: (1) a precalibrated precision model and (2) a mannequin model that served to simulate the human condition. To assess the accuracy of the camera system, repeated images of both models were recorded at two time points, one week apart. Repeated measurements of specific distances were recorded directly on the models and from each image. Means and standard deviations were calculated for all the repeated measurements at each time point. A two-tailed t-test was used to test for significant differences between (1) each distance measured directly on the precision model and the same distance measured on the images of the precision model, (2) each distance measured directly on the mannequin and the same distance measured on the images of the mannequin, and (3) the mean differences between the same distances measured at the two times. The findings showed that substantial image distortion occurred when images of sharp angles (90 degrees) were captured. Also, those images captured from the frontal perspective +/- 15 degrees were the most accurate.     

sALP、sNTX与下颌骨骨密度改变的相关性分析

目的:探讨下颌牙列缺损人群血清碱性磷酸酶(sALP)和Ⅰ型胶原氨基末端肽(sNTX)随年龄变化及其下颌骨PIM指数之间的关系.方法:选用下颌牙列缺损健康患者60例,年龄20～79岁,分成6个年龄段,10岁为一年龄段,其中男性40名、女性20名.全景曲面断层采用PMI指数测量受试者,同时抽取血清测试骨生化指标sALP和sNTX.根据测试数据进行分析.结果:PMI和sALP、sNTX的性别间比较:4个指标均未见具有统计学意义的性别差别.下颌骨密度指标和骨生化指标与年龄关系:下颌骨密度指标(sPMI、iPMI)与年龄呈高度负相关(r值为-0.845,-0.917,P＜0.001),骨生化指标(sALP、sNTX)与年龄呈正相关(r值为0.946,0.423,P＜0.001).sALP和sNTX在20～39岁年龄段较低,自40～49岁年龄段开始明显升高(P＜0.001),sPMI和iPMI在50～59岁年龄段较30～39岁之前年龄段显著下降(P＜0.001).结论:年龄是下颌骨密度指数和骨生化指标变化的重要因素;sALP和sNTX反映下颌骨高骨转换状态,是下颌骨量丢失的重要因素之一;sPMI和iPMI是反映下颌骨密度改变的敏感指标.