基于CT影像计算机辅助分析的活体颌骨种植相关解剖结构测量研究

目的:开发计算机辅助(CAD)交互分析系统,结合放射扫描模板,建立基于CT的活体颌骨测量方法.材料与方法:(1)开发基于CT的CAD系统.(2)对正常牙合志愿者进行以下操作:全口取模、制取模板、标记放射模板阻射点并佩戴该模板进行CT扫描.(3)利用本软件对CT图像进行测量分析.结果:放射模板佩戴准确,标记点显影清晰.本软件可对CT图像进行读取、重建、切割、测量.测量项目包括:牙槽嵴顶与下牙槽神经管、颏孔、上颌窦底、鼻底的距离,牙槽嵴的近远中距及颊舌径,上下牙间覆牙合、覆盖关系及相关夹角等.讨论:(1)放射模板便于快速找到拟种植位点.(2)建立的方法利于为种植外科手术提供准确的解剖学信息.结论:本实验建立了一种基于CT影像的活体颌骨测量的有效方法.     

舌神经至不同磨牙牙龈缘距离的相关性研究

目的:研究舌神经至不同磨牙牙龈缘的距离,并分析其相关性,为临床手术提供解剖学依据.方法:随机选用1980～2006年收集的30具成人头部防腐固定标本进行解剖,测量左、右舌神经至下颌第一、二、三磨牙远中龈缘水平方向、远中舌侧牙龈角向下后45°方向、舌侧龈缘中点垂直向下方向的距离,SPSS 13.0统计软件进行统计学处理及相关性分析.结果:左、右舌神经至下颌第一、二、三磨牙牙龈远中龈缘水平方向、远中舌侧牙龈角向下后45°方向、舌侧龈缘中点垂直向下方向的距离,无统计学意义(P>0.05).舌神经至下颌第三磨牙远中舌侧牙龈角向下后45°方向与舌侧龈缘中点垂直向下方向的距离有相关性(P=0.023<0.05,r=0.293);舌神经至下颌第一磨牙与第二磨牙牙龈缘远中龈缘水平方向的距离存在相关性(P=0.00<0.05,r=0.637).结论:左、右舌神经具有相同的解剖结构及特点;舌神经至下颌第三磨牙远中舌侧牙龈角向下后45°方向与舌侧龈缘中点垂直向下方向的距离存在相关性,但相关程度一般;舌神经至下颌第一磨牙与第二磨牙牙龈远中龈缘水平方向的距离存在相关性,并且相关程度好.     

放射定位标记模板技术在牙种植外科前三维影像分析中的应用

目的探讨放射定位标记模板技术在种植手术前三维影像分析中的作用和意义。方法应用空气压模技术制作标记有放射线阻射剂拟种植位点的放射模板,通过牙种植外科石膏模型,受试注塑模型、颅骨颌骨标本及临床种植病人颌骨的螺旋CT扫描,获取颌骨受植区域拟种植部位骨三维结构CT数据。结果确立的扫描平面即调整牙合平面与地面垂直（与X轴坐标线一致）能获得最佳侧断层图像;所有标记的CT模板均可在CT扫描后的轴位图像及颌重建侧断层和全景图像中清晰显现,且能达到准确的标定预种植位点。结论基于放射标记定位模板的评估方法可为种植外科前三维影像分析提供更为精确的手段,更有助于CAD／CAM种植外科定位导向模板的合理设计。     

离体牙体外实验法对螺旋CT三维重建准确性的评价

目的:应用离体牙体外实验的方法对螺旋CT三维重建测量结果的准确性进行分析比较。方法:对20颗离体牙标本的实验动物模型进行CT扫描和三维重建,并测量标记物边长、标记点到牙根尖距离、牙长、牙根凹陷直径4项指标,与原离体牙标本的游标卡尺测量结果进行统计学比较。结果:比较离体牙标本游标卡尺测量与螺旋CT三维重建测量结果,4项指标均有显著的统计学差异,螺旋CT三维重建测量值小于游标卡尺测量值,当数据精确到1 mm时,测量准确率可达到90%以上。结论:应用螺旋CT三维重建对离体牙进行长度测量,测量值略小于实际长度,将测量数据精确到1 mm时,准确率较高。     

带金属托槽牙列的口内扫描数字模型的精度研究

目的 研究带金属托槽牙列的口内扫描数字模型的精度,为临床及科研工作提供精确的研究模型.方法 选择北京大学口腔医院正畸科门诊患者15例,分别在金属托槽粘接前后使用口内扫描仪(Trios,3Shape,丹麦)获取上颌数字模型.对第一磨牙近中颊尖顶点到同侧中切牙近中切角顶点距离(L1_6;R1_6);第一磨牙间宽度(6_6);尖牙间宽度(3_3);中切牙切缘中点到唇侧龈缘最高点距离(h11;h21)进行测量.重复测量两次并计算组内相关系数(ICC)进行一致性检验.应用配对t检验分析各测量项目在两组模型间的差异.结果 两组模型的所有重复测量ICC＞0.90,测量方法可信.第一磨牙近中颊尖顶点到同侧中切牙近中切角顶点距离(L1_6;R1_6)、第一磨牙间宽度(6_6)、尖牙间宽度(3_3)以及右侧中切牙切缘中点到唇侧龈缘最高点距离(h11)无统计学差异(P＞0.05);在左侧中切牙切缘中点到唇侧龈缘最高点距离(h21)之间差异有统计学意义(P＜0.05),治疗前为(9.51±0.62)mm,粘接托槽后为(9.65±0.68)mm.结论 TRIOS口内扫描仪扫描得到的正畸治疗中带有金属托槽的牙体硬组织的口内数字模型具备较高的扫描精度,基本可以用于治疗过程中模型分析.     

螺旋CT结合Dentascan软件在种植牙术前颌骨评估中的应用

目的：评价螺旋CT结合Dentascan软件和定位模板在种植牙术前颌骨评估中的应用价值。方法：将用压模机制作的透明树脂定位模板戴入植牙患者口内,以0．5mm层厚螺旋CT扫描颌骨。扫描的数据传至CT工作站用Dentascan软件处理后显示侧断层图、曲面断层图及三维重建图。结果：所有25例病例重建图均能清晰的显示颌骨的形态、质地和重要的解剖结构,如上领窦、颏孔、下牙槽神经管,并且能精确的测量缺牙区可用骨的高度、厚度和宽度。结论：螺旋CT结合Dentascan软件和定位模板在种植牙治疗计划的设计中起关键作用,尤其像前牙美容区域,并有利于提高种植牙的成功率。     

种植外科定位模板的制作及CT影像学分析

目的通过种植外科定位模板的制作及计算机断层(Computed Tomography,CT)影像学的分析,便于牙种植体的精确植入及其美学修复。方法选择20例牙列缺损患者,制取上下颌印模,灌注超硬石膏。在石膏模型上根据邻牙及咬合关系制作种植外科定位模板,患者佩戴模板进行CT扫描,利用自主开发的牙颌种植辅助诊断系统V5.4软件对CT数据进行影像学分析。结果 CT影像可以清晰地获得受植区颌骨的三维解剖结构,并能精确地测量受植区骨组织颊(唇)舌向宽度、牙槽嵴顶到下牙槽神经管上壁或上颌窦底的高度、受植区的软组织厚度;还可以测量前牙区理想的种植方向与牙槽嵴方向的差异。植入的种植体位置和方向佳,无术后并发症,且后期修复效果较好。结论种植外科定位模板的CT影像分析可以准确了解种植区骨质,对选择种植体的长度和直径,及其评估后期的种植修复有很大帮助。     

MSCT成像技术在上颌前牙美学区牙种植术中的应用

目的:探讨多层螺旋CT(MSCT)成像技术在上颌前牙美学区牙种植术的临床应用效果。方法:门诊选取18例上颌前牙美学区单个牙缺失患者,牙种植术前及术后均行64排螺旋CT薄层容积扫描,通过专用Dental软件及三维重建技术进行图像后处理。结果:应用Dental软件及三维重建技术可以获得术前拟种植区颌骨的全景形态,剩余牙槽嵴的高度、宽度及与鼻底的关系等,同时术后的重建图像可以显示种植体的轴向位置、深度、唇侧骨板厚度及与邻牙的空间关系等。讨论:在上颌前牙美学区,多层螺旋CT(MSCT)成像技术能够准确显示缺牙区颌骨的表面解剖形态以及与鼻腔底的毗邻关系,能准确显示骨量不足的具体情况,能精确测量出剩余牙槽嵴的高度、宽度及近远中距离,并指导手术医师进行正确的植骨选择及种植体正确的植入方向,能有效地避免各种并发症,同时可以反映牙种植体在颌骨的位置、方向以及与周围组织的关系等情况,评价种植手术效果。结论:在上颌前牙美学区行牙种植术时,MSCT成像技术为手术医师制订最佳牙种植手术方案提供了重要依据,还能评价术后的种植手术效果,保证种植修复的成功率。     

颈缘线处理中邻间隙龈中点线概念的引入

本文的第一个目的是研究上颌前牙区龈缘最低点与邻间隙龈中点（IGM）线的关系。在观察的77位病人模型上标记出牙颈缘最低点及近、远中邻间隙的龈中点后,在硅橡胶模型上测量出连接邻间隙龈中点的IGM线到颈缘最低点的最短距离。结果显示上颌中切牙颈缘最低点的平均位置与IGM线一致。在上颌侧切牙,颈缘的最低点在IGM线腭侧0．24mm．而在尖牙则位于唇侧03mm。本研究的第二个目的是通过一些病例于颈缘线处理中．IGM线概念的引入。一位牙龈厚平生物型的患者．采用临床牙冠延长手术治疗,经过对牙龈冠向生长情况的长时间观察,发现颈缘最低点最终与IGM线接近。而对一个薄扇牙龈生物型的病例短期观察中,发现邻间隙牙龈增加后游离龈也会增加。在一个Miller I度牙龈退缩的病例中．基于IGM线的概念,进行了一个冠向复位瓣联合转瓣技术的手术。根据本研究及临床病例观察得到的结果,IGM线有可能成为牙周成形手术中颈缘线处理的参照标准。     

前牙龈下残根正畸牵引后冠修复的临床疗效观察

目的探讨前牙龈下残根经正畸牵引后冠修复的临床疗效。方法断面位于龈下1～3mm的前牙残根40颗,行完善根管治疗后正畸牵引,粘接纤维桩,计算机辅助设计与制作（computer-aideddesign/computer-aidedmanufacture,CAD/CAM）全冠。正畸牵引前、后摄X线片,测量残根断缘距牙槽嵴顶的距离;用扩大针标记并测量残根断缘距龈缘的距离;计算牵引距离。冠修复后3、6、24个月复查,评价疗效。结果正畸牵引龈下残根6～8周后,所有残根断缘均超出龈缘。40颗残根断缘距龈缘的平均距离1.15mm;残根断缘距牙槽嵴顶的平均距离3.85mm;平均牵引距离2.59mm。CAD/CAM全冠修复后随访24个月,40颗患牙稳固且牙龈健康,美观效果好,牵引后位置稳定。结论前牙残根经正畸牵引后行冠修复可达到美容和功能兼顾的较好效果。     

多层面螺旋CT的口腔种植体定位研究

目的 探讨多层面螺旋CT的后处理重建技术在口腔种植体植入术前精确定位及骨量测量的意义。方法测量比较带有3个放射标记物的模板在模型及多层面螺旋CT影像中的距离和相互角度,并在CT影像中虚拟植入种植体,观察种植体植入情况。结果 多层面螺旋CT中影像的放射标记物间的距离与模型上测量数据的差异无统计学意义,并能直观、准确提供种植体植入的骨量信息。结论 使用多层面螺旋CT能在术前准确评估牙槽骨骨量及确定种植体植入位置、方向、大小、长度。     

多层螺旋CT牙体表面成像在诊断上颌埋伏牙中的应用

目的:探讨多层螺旋CT牙体表面成像在上颌埋伏牙诊断中的临床应用。方法:对82例临床怀疑上颌埋伏牙患者行上颌牙轴位螺旋CT容积扫描,应用多层螺旋CT的图像后处理技术作多层面重建(mu ltip la-nar reform ation,MPR)和三维重建(3-d im ensional reconstruction,3D),获得单纯牙体的任意方向的三维立体图像或任意曲面的断层像。结果:多层螺旋CT三维重建图像能立体全方位地显示上颌埋伏牙的形态、位置、萌出方向及其与周围组织的关系。结论:多层螺旋CT后处理技术能立体、直观地提供临床医师所需信息,在上颌埋伏牙的正畸治疗中有重要的诊断和指导治疗的意义。     

Comparison of cone-beam and conventional multislice computed tomography for image-guided dental implant planning

Objectives

To compare the accuracy of cone-beam CT (CBCT) and multislice CT (MSCT) with regard to its use in image-guided dental implant surgery in a prospective model based study.

Material and methods

Ten photopolymer-acrylate mandibula models, each with four precise metal reference markers, were scanned with MSCT and CBCT. The six reference distances between the markers were measured by a three-axis milling machine first. The distances were then measured by (1) navigation with the Medtronic StealthStation® TREON? image-guided surgery system, (2) with the Medtronic planning-tool and (3) on the PC with the Mimics® software. Mean values were calculated for all three methods for CBCT and MSCT and were compared for statistical significance.

Results

Of all measurements, 83% of the arithmetic mean values were within the ±0.5 mm range (MSCT 88% and CBCT 78%) and 17% within the ±1.0 mm range (MSCT 12% and CBCT 22%). The absolute difference of the arithmetic mean values showed no statistically significant difference between MSCT and CBCT. The difference of the overall mean values to the reference was 0.43 mm for MSCT and 0.46 mm for CBCT.

Conclusions

The data of our study prove that the application of CBCT for the indicated purpose yielded good results comparable to those of MSCT. All three measuring methods were feasible and accuracy was statistically not different between the data acquired by MSCT and CBCT within the setting of this study.     

牙科CT系统测量正常人牙齿外部形态数据的可行性研究

目的:探讨牙科CT系统测量正常人牙齿形态数据的可行性。方法:对10名正常青年人(男性6例、女性4例,年龄24～27岁)进行牙科CT扫描,用其随机自带软件测量牙冠宽度及厚度,并制取上述10名青年人上下颌全牙列石膏模型,用游标卡尺测量模型的牙冠宽度及厚度;应用SPSS软件对牙科CT系统与游标卡尺所测数据进行统计学分析。结果:牙科CT系统与游标卡尺对牙冠宽度及厚度进行的两次测量结果均无统计学差异(P>0.05);牙科CT与游标卡尺对牙冠宽度、厚度两次测量结果的平均值无统计学差异(P>0.05)。结论:牙科CT系统测量牙齿外部形态数据稳定、可靠,可用于测量活体全牙列牙齿外部形态数据。     

Comparison of digital dental images yielded by digital dental casts,cone-beam computed tomography,and multislice computed tomography for measurement of dental area

Objectives

We investigated and compared the errors generated by multislice computed tomography (MSCT), cone-beam computed tomography (CBCT), and digital dental casts when used to provide digital data about dental structures.

Methods

Ten A20 skull models were scanned with MSCT and CBCT, and dental plaster cast models were optically scanned in three dimensions. The maxillary dental area was then compared. The distance between the three-dimensional scan data of the skull and each set of digital dental data were measured. Reference data were then overlapped with the experimental digital model using surface-based registration. The distance of errors was measured with the shortest distance measurement function. The distances between each experimental digital model and the reference scan data were measured, and error values were determined for all maxillary teeth and each tooth surface area. Errors were measured for all teeth from the central incisors to the second molar on both the left and right sides. Errors were measured from the mesial, distal, and labial surfaces and the tooth cusp tip area for each tooth.

Results

The digital dental casts had the smallest error (p < 0.001). The error in the digital dental casts (mean ± standard deviation) was 0.10 ± 0.12 mm. The CBCT error was 0.34 ± 0.38 mm, which was significantly greater than the MSCT error (0.19 ± 0.16 mm) (p < 0.001).

Conclusions

We recommend the use of digital dental casts with digital dental imaging for three-dimensional measurement of the dental area because this technique had the smallest errors.

     

上颌平面偏斜对牙列中线与正中矢状面吻合度影响

目的:针对颌面部不对称畸形患者,在计算机上应用正颌手术模拟软件,重建三维头颅模型并模拟正颌手术,通过对术前上颌平面偏斜的角度和模拟正颌术后上颌牙列中线与正中矢状面夹角的分析,得出二者之间的关系,为正颌手术提供参考。方法:选择在中国医科大学附属口腔医院口腔颌面外科就诊的20位颌面部不对称畸形患者进行研究,首先用三维CT影像重建出头颅模型,测量上颌平面与水平参考面的夹角,再利用软件模拟上颌Le FortⅠ型截骨,测量上颌牙列中线与正中矢状面的夹角,最后应用统计学软件进行统计分析,得出两个角度间的关系。结果:颌面部不对称畸形患者,上颌平面和水平参考面的夹角与上颌牙列中线和正中矢状面夹角存在正相关的线性关系,经过统计学分析,得到上颌平面和水平参考面的夹角X与上颌牙列中线与正中矢状面夹角Y的直线回归方程,为Y=1.997+12.109X。结论:颌面部不对称畸形患者,上颌平面偏斜对牙列中线与正中矢状面的吻合度存在相关性,该相关性可为正颌手术的整复提供原则性的参考。     

Comparative study of image quality and radiation dose of cone beam and low-dose multislice computed tomography - an in-vitro investigation

Objectives

The aim of this study was to evaluate the image quality and dose exposition of different cone-beam computed tomography (CBCT) and low-dose multislice spiral CT (MSCT) scanners.

Materials and methods

A human cadaver head was examined with three MSCT and five CBCT scanners. The radiation dose was measured using an Alderson RANDO phantom. Standard protocols were used to obtain the CBCT data. For the MSCT devices, the tube voltage and tube current were modified to obtain acceptable image quality while keeping the radiation dose as low as possible. The image quality of MSCT and CBCT devices was determined by examining the enamel–dentin and dentin–pulp interface and the periodontal ligament space of 22 teeth.

Results

Inter- and intra-observer agreement was found for the different groups of raters. CBCT systems were rated superior to MSCT devices in terms of image quality for all dental structures. The differences in image quality among the studied CBCT and MSCT scanner groups did not turn out to be significant but were significant between CBCT and MSCT devices. The organ dose varied considerably between the different CBCT and MSCT devices. The differences concerning the organ dose were notably pronounced in the area of the eye lens.

Conclusions

The tested devices exhibited significant differences with respect to the organ dose. The variance was particularly pronounced in the CBCT devices. With a dose exposition equal or lower than the CBCT, the image quality in the MSCT devices was judged to be significantly worse.     

Prospective study to estimate mandibular cancellous bone density using large‐volume cone‐beam computed tomography

Objective: Because pixel or voxel values obtained from cone‐beam computed tomography (CBCT) images are not absolute values, the bone density cannot be evaluated. Hence, the regression line between voxel values of CBCT and the bone mineral density (BMDs) of multislice CT (MSCT) was prospectively evaluated to investigate the mandibular cancellous bone density. Also, the usefulness of a reference bone block was evaluated on assessing a low mandibular bone density. Materials and methods: A total of 15 (two males and 13 females) patients who had undergone postoperative imaging for mandibular dental implant treatment with a bone graft using CBCT and MSCT were enrolled in this investigation. Voxel values of region of interests in CBCT were transformed to BMDs using a regression line from a previous study, and differences between BMDs obtained using CBCT and MSCT were calculated. Also, the voxel values of CBCT at the selected sites, in which the bone density was measured between 100 and 300 mg/cm³ of hydroxyapatite (HA) in MSCT, were assessed regarding whether they were higher or lower than the BMD of the reference bone block. Results: The mean overall difference was 38 mg/cm³ of HA. Thirty‐eight of the 45 sites (84%) were accurately assessed using the reference bone block. Conclusion: The usefulness of a regression line for BMD estimation in CBCT was prospectively confirmed in mandibular cancellous bone. Also, the reference bone block was useful to assess the low bone density of mandibular cancellous bone on CBCT with a large volume. To cite this article:
Naitoh M, Hirukawa A, Katsumata A, Ariji E. Prospective study to estimate mandibular cancellous bone density using large‐volume cone‐beam computed tomography.
Clin. Oral Impl. Res. xx , 2010; 1309–1313.
doi: 10.1111/j.1600‐0501.2010.01950.x     

几种骨量测定方法在上颌骨中应用的比较研究

目的:探讨不同骨量测定方法在上颌骨骨量测定中的应用价值,为上颌骨牙种植手术方案的制定提供依据。方法:采用手工直接测量(DM)法、螺旋CT测量法、X线曲面体层(OP)测量法对15副头颅标本的牙槽骨高度、宽度进行测量,比较研究螺旋CT与OP骨高度值及骨宽度值的失真率;并在螺旋CT三维重建图像上对上颌窦底壁、上颌唇(颊)侧骨板的骨质形貌进行观察分析。结果:螺旋CT扫描三维重建在显示上颌骨骨质内部结构和表面形貌,测量缺牙区骨量以及与邻牙、上颌窦等的距离等方面优于DM法和OP法。结论:螺旋CT对上颌骨牙种植术的骨量测定有重要的价值。     

江苏地区正常的牙弓形态

目的:通过对125名江苏地区正常人群的模型测量,建立江苏地区正常牙弓宽度及长度的平均值,并分析牙弓形态特征,为正畸临床的诊断和治疗提供依据。方法:选取正常模型125副(男61副,女64副),用扫描仪输入电脑,运用Winceph 8.0软件测量牙弓宽度及长度,对测量结果进行统计分析。结果:确立了以Currier外侧曲线为参考点的正常各段牙弓宽度及长度的平均值,结果表明江苏地区正常人群中,男性牙弓宽度及长度均大于女性。构建了江苏地区正常的牙弓形态,并建立了牙弓形态的β函数。结论:牙弓形态存在种族、地区和性别的差异,临床上应参照本民族、本地区的标准。β函数有助于指导临床错的诊断和治疗。