上颌埋伏阻生中切牙的影像学分类

目的:探讨上颌埋伏阻生中切牙的三维图像分类特征。方法:根据103例上颌中切牙埋伏阻生患者螺旋CT的Dicom原始数据,应用Mimics10.0软件重建出上颌埋伏阻生中切牙的三维图像,分析上颌埋伏阻生中切牙的阻生特点,并对其进行分类。结果:共有埋伏牙106颗。74颗牙为唇侧阻生,倒置阻生33颗,水平阻生28颗,倾斜阻生13颗;20颗为腭侧阻生,倾斜阻生11颗,水平阻生9颗;12颗为垂直阻生。上颌埋伏阻生中切牙根据牙冠的位置在垂直向、冠状向、矢状向可分为3类,即①唇侧埋伏阻生型,包括唇侧倾斜埋伏阻生型、唇侧前后水平埋伏阻生型、唇侧倒置埋伏阻生型;②腭侧埋伏阻生型,包括腭侧倾斜埋伏阻生型、腭侧后前水平埋伏阻生型;③垂直埋伏阻生型。结论:上颌埋伏阻生中切牙从三维方向上可分为3类,每一类又可分多个亚型,包括唇侧(倾斜、前后水平、倒置)埋伏阻生、腭侧(倾斜、后前水平)埋伏阻生和垂直埋伏阻生。     

埋伏弯根上颌中切牙序列矫治的研究

目的探讨埋伏弯根上颌中切牙有效的正畸牵引治疗方法。方法选择11例患者共12颗埋伏弯根上颌中切牙为研究对象,常规拍摄定位X线片,配合口内检查、模型分析等,确定埋伏牙的位置及其与邻牙的相互关系,采用封闭式导萌、选择性根管治疗及根尖切除术、修复治疗等方法进行矫治。结果12颗埋伏牙通过治疗后顺利进入正常牙列,未见牙根吸收粘连,建立了良好的咬合关系。9例唇侧埋伏弯根上颌中切牙患者的临床牙冠唇倾角度较大,4例根尖位于唇侧黏膜下,进行了根管治疗加根尖切除术,其中1例行烤瓷冠改形修复;其余5例未做根管治疗,暂行观察。2例腭侧埋伏弯根上颌中切牙的疗效稳定。结论埋伏弯根上颌中切牙采用序列矫治可以取得良好的美观和功能效果。     

螺旋CT多方式三维重建在上颌埋伏前牙定位中的综合应用

目的 评价螺旋CT三维重建在上颌埋伏前牙定位诊断中的价值。方法 对常规拍摄全颌曲面断层片和根尖片不易清楚判断埋伏牙形态、位置及与邻牙关系的72例患者,应用螺旋CT进行容积扫描,分别采用最大密度投影法(maximum in-tensity projection,MIP)、多平面重建(multi planar reconstruction,MPR)、容积再现法(volume rendering,VR)获得立体的牙体表面图像,显示上颌埋伏前牙的形态、位置及与邻牙的关系。结果 经MIP、MPR、VR三种方式重建处理后,72例病例均清晰显示了上颌埋伏前牙的牙体形态、唇腭向位置、萌出方向以及与邻牙的关系。结论 螺旋CT多方式三维重建的综合运用可为上颌埋伏前牙的定位诊断提供更为客观的依据。     

不同牵引部位对上颌埋伏中切牙牙周应力分布的影响

目的:基于对上颌唇向倒置埋伏中切牙的三维有限元模型施加不同部位的牵引力,分析比较不同工况下牙周膜的应力分布,从而为临床进行上颌埋伏中切牙助萌治疗提供参考。方法:选取1名上颌中切牙唇向倒置埋伏阻生患者的锥体束CT(CBCT)原始数据,建立统一坐标系下上颌埋伏中切牙及其支持组织的三维有限元模型。在牙冠舌面切1/3、中1/3、颈1/3的中心分别施加在矢状方向上垂直于牙体长轴的30 g、60 g、90 g的牵引力,分析比较不同工况下牙周膜的应力分布情况。结果:不同牵引部位下,埋伏牙牙周应力分布特点类似。同一力值牵引,牵引部位越靠近牙颈部,牙周膜的应力越小;同一牵引部位,牵引力越大,牙周应力越大。结论:牵引部位应尽量位于切端,牵引力不宜超过60 g。     

上颌埋伏阻生尖牙在锥形束CT和曲面体层片中的位置分布及特征研究

目的　通过分析上颌埋伏阻生尖牙在曲面体层片上牙冠和牙根所在区域、牙轴倾斜度及牙齿长度,对照其在锥形束CT（cone-beam computed tomography,CBCT）上的位置,找出上颌埋伏阻生尖牙的曲面体层片预测因素。方法　选取2006—2018年于中国医科大学附属口腔医院正畸科就诊的单侧上颌埋伏阻生尖牙患者135例,共计上颌埋伏阻生尖牙135颗为研究组,同一患者对侧非埋伏阻生尖牙135颗为对照组。（1）采用NNT Viewer软件、Planmeca Dimaxis Pro软件分别对患者的CBCT图像和曲面体层片进行测量,将曲面体层片中上颌埋伏阻生尖牙近远中向位置分为5区（Ⅰ ~ Ⅴ区）,其唇腭侧位置由CBCT判定,分析两者相关性。（2）在曲面体层片中测量分析研究组与对照组牙冠及牙根的近远中向位置分布、牙轴倾斜度以及牙齿长度的差异。结果　（1）不同性别患者上颌埋伏阻生尖牙唇腭侧位置分布的差异有统计学意义（χ2 = 13.542,P = 0.001）。曲面体层片中上颌埋伏阻生尖牙牙根近远中向的区域定位与CBCT中相应阻生尖牙的唇腭侧位之间有显著相关性（r = 0. 225,P = 0.009）;但其牙冠间无相关性（r = 0.001,P = 0.991）。（2）两组尖牙牙冠及牙根近远中向位置分布差异有统计学意义（χ2值分别为219.263、68.447,均P < 0.001）。研究组较对照组尖牙牙齿长度短,牙轴倾斜度大（均P < 0.05）。结论　利用曲面体层片中上颌阻生尖牙牙根近远中向的区域定位可预测其唇腭侧位。在曲面体层片中牙根近远中向位置和牙齿长度的测量结果可用于预测上颌埋伏阻生尖牙的发生。     

上颌中切牙牙龈生物型的相关因素分析

目的评估不同参考线处上颌中切牙唇、腭侧骨板厚度情况及釉牙骨质界到唇侧牙槽嵴顶距离;探究上颌中切牙牙龈生物型与性别、年龄、牙冠唇面形态、牙槽骨厚度以及与釉牙骨质界到唇侧牙槽嵴顶距离的相关性。方法对118位受试者进行CBCT扫描,测量上颌中切牙唇、腭侧骨板厚度情况、釉牙骨质界到牙槽嵴顶距离;使用牙周探针法测量上述受试者的牙龈生物型,记录并分析其相关性结果牙龈生物型与性别、年龄、中切牙唇面形态无明显相关性;上颌中切牙的釉牙骨质界至唇侧牙槽嵴顶距离为(2.63±0.98)mm,牙龈生物型与该距离无相关性(r=-0.051,P>0.05),27.1%的唇侧骨板部分缺失;牙龈生物型与距釉牙骨质界根方3 mm、5 mm处唇侧骨板厚度的相关系数(r)分别为0.747、0.281(P<0.05)结论 (1)上颌中切牙接近1/3的唇侧骨板伴有部分缺失,釉牙骨质界至唇侧牙槽嵴顶距离与牙龈生物型无相关性;(2)当患者上颌中切牙唇侧骨板完整时,牙龈生物型与唇侧骨板厚度呈正相关。     

牙囊在埋伏上颌中切牙唇侧微创开放式牵引中的作用探讨

目的 总结既往上前牙区埋伏牙开放式牵引方法的基础上,报告一种基于牙囊的软组织处理技术,并监测治疗后埋伏牙牙根长度变化和牙槽骨丢失量,探讨牙囊在埋伏上颌中切牙唇侧微创开放式牵引中的重要作用。方法 选择单侧唇侧埋伏上颌中切牙并采用开放式牵引技术治疗的患者,将埋伏中切牙纳入试验组,将对侧未受影响的中切牙纳入对照组。在外科手术暴露埋伏上颌中切牙时,利用埋伏牙周围的牙囊组织进行术区软组织管理,最大程度地保存埋伏牙周围软硬组织量。在埋伏上颌中切牙牵引至平面后,记录其牙长、根长、骨丢失量、骨厚度等测量值。结果 成功牵引了17例单侧唇侧埋伏上颌中切牙。牵引后试验组与对照组之间,牙长、根长、唇侧骨丢失量的差异有统计学意义（P<0.05）,唇-腭釉牙骨质界处宽度、腭侧骨丢失量、唇侧骨厚度、腭侧骨厚度、根尖牙槽骨厚度的差异无统计学意义（P>0.05）。结论 在外科手术暴露唇侧埋伏上颌中切牙时,本方法利用埋伏牙周围的牙囊组织进行术区软组织管理,最大程度地保存埋伏牙周围软硬组织量,尽可能在牵引萌出后获得更好的美学效果和健康的牙周组织。     

上颌埋伏阻生中切牙的临床研究

目的统计温州医学院附属口腔医院正畸科门诊病例中上颌埋伏阻生中切牙的患病率、唇腭侧的比例及治疗情况。方法选取2005年1月至2008年1月期间,在温州医学院附属口腔医院正畸科就诊的错殆患者中,所有在放射科拍摄过螺旋CT的上颌中切牙埋伏阻生的患者。统计其发病、治疗情况。结果2005年1月至2008年1月期间,在温州医学院附属口腔医院正畸科共有8763名患者,上颌中切牙埋伏阻生者共103名。男性50名,女性53名。唇侧阻生71名（其中3名为双侧阻生）,腭侧阻生20名,垂直阻生12名。其中76颗埋伏牙采用外科手术结合正畸牵引治疗,27颗采取外科拔除,3颗采用减阻助萌术。结论在温州医学院附属口腔医院正畸门诊患者中上颌中切牙埋伏阻生约占1．18％,男女比例基本一致,唇侧阻生最常见,上颌埋伏阻生中切牙的治疗以外科手术结合正畸治疗为主。     

螺旋CT在儿童上颌前部埋伏牙定位中的临床应用

目的:探讨螺旋CT在儿童上颌前部埋伏阻生牙中定位的准确性及临床应用价值。方法:在2004年6月—2009年12月间就诊的89例埋伏阻生牙患者中,选取对常规咬合片和全颌曲面断层片不能清楚定位的30例上颌骨埋伏牙患者行螺旋CT扫描。应用螺旋CT的图像处理功能作多层面重建(MPR)和表面遮盖技术(SSD),观察片中埋伏牙的数目、大小、形态、唇腭向位置、与周围组织的关系以及冠根形成的角度。通过手术暴露窗口,评估螺旋CT定位的准确性和临床应用价值。结果:上颌骨内埋伏阻生牙33颗,均能准确无误地显示出埋伏牙的方向、形态、数目、唇腭侧骨质厚度。结论:螺旋CT能精准定位儿童上颌前部埋伏阻生牙并为手术提供最佳路径,在临床工作中具有重要的指导作用。     

上颌倒置弯根阻生中切牙的分类及正畸牵引适应征探讨

上颌中切牙倒置弯根是一种特殊类型的阻生,以牙冠唇侧倒置居多,文献多见个例报道[1,2]。对弯根的定义,是指牙根相对牙冠或牙长轴弯曲超过90°[3],而不仅仅是根尖弯曲。有学者应用锥形束CT或全景片评价唇侧倒置或腭侧阻生上中切牙的正畸矫治疗效[4,5],但未论及阻生牙弯根类型及弯根程度。本文回顾性研究倒置弯根上颌中切牙阻生病例,根据冠根相对位置分类,并通过对正畸牵引成功与不成功病例的对比分析,     

三维CT在颅底影像诊断中的应用

目的　探索三维 Ｃ Ｔ 成像在颅底中的应用价值。方法　对２５ 个病例的颅底行 Ｃ Ｔ横断扫描,采用表面阴影显示（ Ｓ Ｓ Ｄ）法进行颅底骨三维重建,分析病变引起颅底骨质改变在三维重建图像上的表现。结果　４ 例颅底骨折的三维重建提供了更多的骨折征象。１５ 例颅底病变术前或术后三维重建为手术方案制定、术后评价、随访及进一步治疗提供了客观真实的立体参考资料。６ 例三叉神经痛射频治疗过程中三维重建有利于制定更安全可靠的穿刺进针线路。结论　在二维 Ｃ Ｔ 基础上的三维成像对检查解剖结构复杂而不规则的颅底是非常有意义的 。     

Assessment of three-dimensional X-ray images: reconstruction from conventional tomograms, compact computerized tomography images, and multislice helical computerized tomography images

Three-dimensional X-ray images (3D images) were used for imaging diagnosis in the oral and maxillofacial region. These images could be fundamentally reconstructed from various tomograms, though clinical 3D images were mainly reconstructed from computerized tomography (CT) images. In this investigation, 3D images were reconstructed from conventional tomograms with a panoramic unit, compact CT images, and multislice helical CT images, and the usefulness of each system was subjectively assessed for dental implant treatment. Three hemilateral dried human mandibles were used and were examined by linear tomography with a panoramic unit, compact CT, and multislice helical CT, and 3D images were reconstructed by using the rendering software for each system. The 3D images were visually evaluated on a 5-point scale covering the alveolar ridge, buccal and lingual bone surface, mental foramen, and tooth sockets. As a result, 3D images reconstructed from conventional tomograms with the panoramic unit were assessed as fair to unsure, compact CT 3D images were assessed as unsure to good, and multislice helical CT 3D images were assessed as good to excellent. It was concluded that compact CT 3D images and multislice helical CT 3D images were useful in dental implant treatment.     

Validity of computed tomography in diagnosing midfacial fractures

The aim of this study was to evaluate the sensitivity, accuracy, and reliability of two-dimensional computed tomography (2D-CT) scans (axial, coronal, sagittal planes) and three-dimensional computed tomography (3D-CT) reconstructions in diagnosing midfacial fractures in relation to actual fractures identified clinically and during surgery (gold standard). The imaging diagnosis was performed by a radiologist and an oral and maxillofacial surgeon. Sixty-two patients with a total of 429 midfacial fractures were included. Frontal sinus and nose fractures were easily diagnosed. For the three CT planes, there was a statistically significant difference between the CT examination and the gold standard for five to seven of the nine bones evaluated, while for 3D-CT, a difference was observed only for fractures of the orbital floor. The inter-observer agreement between the oral and maxillofacial surgeon and the radiologist was 75.5%. In conclusion, in this study 3D-CT reconstructions showed significantly the best sensitivity, accuracy, and reliability for the diagnosis of midfacial fractures. The sagittal reconstructions were the least diagnostic of the 2D-CT images. For areas where the parameters studied showed less agreement and hence a more difficult diagnosis, we recommend a combination of 3D and 2D-CT images to improve diagnostic accuracy.     

Relative en- and exophthalmometry in zygomatic fractures comparing optical non-contact, non-ionizing 3D imaging to the Hertel instrument and computed tomography

AIM: It is the aim of the present study to introduce non-contact, non-invasive optical 3D imaging to relative exophthalmometry and to compare the resulting data to exophthalmometry values assessed by the Hertel instrument and computed tomography. PATIENTS AND METHODS: 20 patients (3 female, 17 male, 44.4+/-16.6 years) without orbital pathology, who were examined by computed tomography of head and neck for the exclusion of different diseases, and seven patients (1 female, 6 male, 40.1+/-14.4 years), who received routine orbital computed tomography because of zygomatic fractures, were included in the study. Optical 3D images of the facial surface were assessed and Hertel exophthalmometry was carried out to determine the relative globe position. In patients with zygomatic fractures the assessment of optical 3D images and Hertel values was repeated 5 days after surgery. RESULTS: For patients without orbital pathology relative exophthalmometry data were 1.4+/-1.1 mm for the Hertel instrument, 0.9+/-1.0 mm for computed tomography and 0.5+/-0.5 mm for optical 3D imaging. The values for Hertel exophthalmometry and computed tomography did not differ statistically significantly (p(Herteldifferencepreop/CTdifferencepreop)=0.284), while there was a significant difference between Hertel exophthalmometry and optical 3D imaging (p(Herteldifferencepreop/opticaldifferencepreop)=0.008). In the cases of zygomatic fractures, Hertel exophthalmometry revealed less pronounced relative differences in globe position than CT and optical 3D imaging data (Hertel 0.7+/-1.1 mm, CT 1.9+/-1.0 mm, optical 3D imaging 1.9+/-1.0 mm). Postoperatively, relative Hertel exophthalmometry showed an increased value revealing a more pronounced enophthalmos (1.7+/-1.0 mm), while the corresponding value of the optical 3D images decreased as a sign for normalization of the globe position (1.1+/-0.7 mm). CONCLUSION: Because of its reliance on the lateral orbital rims Hertel exophthalmometry can lead to an under- or overestimation of enophthalmos, when soft tissue oedema or a dislocation of the orbital rim are present. The combination of computed tomography as baseline measurement and optical 3D imaging for the follow-up examinations reveal more realistic data in cases of zygomatic fractures. Therefore, they should be preferred to the determination of Hertel values especially in more complex cases.     

Geometric accuracy of digital volume tomography and conventional computed tomography

Digital volume tomography is a recently established imaging method that is based on the principle of cone beam computed tomography (CBCT). One of its main applications is imaging in dental and maxillofacial surgery. The objective of this study was to compare the geometric accuracy of digital volume tomographic imaging with that of conventional CT and to assess the suitability for image-guided operating.A calibration cube with a defined pattern of tubes inside was scanned using CT and digital volume tomography. Spatial accuracy was analysed with a software evaluation tool. The positions of the intersections of the tubes were detected in imaging data and registered to the real positions in the calibration body. The deviation was calculated and compared for CT and digital volume tomography.Resolution of spatial images was similar for both methods. However, the spatial accuracy in digital volume tomography was slightly lower than that of CT but still in the submillimetric range. The accuracy was better in the middle, but lower in the margins of the volume. This is a disadvantage in technical image quality, but does not affect the diagnostic image quality. The geometric accuracy is sufficient for digital volume tomography-based image-guided surgery.     

Implagraphy牙颌面锥形束CT与多层螺旋CT的图像质量对比研究

目的：比较牙颌面锥形束CT与多层螺旋CT的图像质量。方法：分别使用牙颌面锥形束CT和多层螺旋CT对实验模体进行扫描，比较两者显示牙、牙周组织、颌面骨解剖结构的差异。结果：牙颌面锥形束CT图像质量，优于多层螺旋CT。结论：牙颌面锥形束CT因其优秀的图像质量，更加适合口腔临床的需要。     

Craniomaxillofacial patient-specific CAD/CAM implants based on cone-beam tomography data – A feasibility study

Customized implants have simplified surgical procedures and have improved patient outcome in craniomaxillofacial surgery. Traditionally, patient-specific data is gathered by conventional computed tomography (CT). However, cone-beam CT (CBCT) can generate a 3D reconstruction of the area of interest with a lower dose of radiation at reduced cost. In this study, we investigated the feasibility of using CBCT data to design and generate customized implants for patients requiring craniomaxillofacial reconstruction. We used CBCT to generate 62 implants for 51 consecutive patients admitted to our department between January 2015 and December 2017. The indications for reconstruction and types of reconstruction were very variable. In all cases, the implants were well fitted and no implant-related complications were detected. Pre-surgical planning was faster and more efficient as we did not have to consult a radiologist. Although CBCT data is more difficult to process than conventional CT data for the implant provider, the clinical advantages are pronounced and we now use CBCT as standard in our department. In conclusion, we have shown that using CBCT to design and manufacture customized implants for reconstruction of the craniomaxillofacial area is feasible and recommend this approach to other departments.     

Construction of three-dimensional tooth model by micro-computed tomography and application for data sharing

The study of dental morphology is essential in terms of phylogeny. Advances in three-dimensional (3D) measurement devices have enabled us to make 3D images of teeth without destruction of samples. However, raw fundamental data on tooth shape requires complex equipment and techniques. An online database of 3D teeth models is therefore indispensable. We aimed to explore the basic methodology for constructing 3D teeth models, with application for data sharing. Geometric information on the human permanent upper left incisor was obtained using micro-computed tomography (micro-CT). Enamel, dentine, and pulp were segmented by thresholding of different gray-scale intensities. Segmented data were separately exported in STereo-Lithography Interface Format (STL). STL data were converted to Wavefront OBJ (OBJect), as many 3D computer graphics programs support the Wavefront OBJ format. Data were also applied to Quick Time Virtual Reality (QTVR) format, which allows the image to be viewed from any direction. In addition to Wavefront OBJ and QTVR data, the original CT series were provided as 16-bit Tag Image File Format (TIFF) images on the website. In conclusion, 3D teeth models were constructed in general-purpose data formats, using micro-CT and commercially available programs. Teeth models that can be used widely would benefit all those who study dental morphology.     

多层螺旋CT技术在颌面部牵张成骨术中的应用

目的探讨多层螺旋CT重建技术在颌面部牵张成骨中的应用方法和价值。方法在12例颌面部牵张成骨患者中应用多层螺旋CT扫描,进行三维及断层图像重建,测量骨牵开距离、牵开区骨厚度和骨密度等指标,考察牵引和成骨效果。结果多层螺旋CT三维重建图像清晰、细致,可各向旋转,有利于观察骨质和骨量;根据具体需要,可利用数据资料及Mimics等软件在个人电脑上重建断层图像,进行直观观察并可测量骨牵开区距离、厚度、密度等指标。12例患者的骨牵开距离均值为16.73 mm,效果良好。结论在多层螺旋CT薄层扫描基础上,可重建清晰、直观的三维及断层图像并可进行相关测量,该技术在颌面部牵张成骨观测中具有良好的应用前景。     

正电子发射体层成像/计算机断层扫描在口腔颌面部肿瘤颈部淋巴结转移中的诊断价值

目的评价正电子发射体层成像/计算机断层扫描（PET/CT）在口腔颌面部肿瘤颈部淋巴结转移诊断中的价值。方法检索中国生物医学文献数据库、Medline（OVID）和EMBASE（检索时间为2010年12月13日）,并采用手工检索19种中文口腔医学期刊的方法收集PET/CT对口腔颌面部肿瘤颈部淋巴结转移的诊断性试验。由2名研究者分别进行文献纳入及文献质量评价,应用MetaDisc 1.4进行Meta分析。结果共9篇文献符合纳入标准。Meta分析结果显示PET/CT对口腔颌面部肿瘤颈部淋巴结转移（以淋巴结分区为单位）的合并敏感度、合并特异度分别为0.84、0.93;诊断比值比为47.89;工作曲线下面积为0.973 8。结论PET/CT对口腔颌面部肿瘤颈部淋巴结转移的诊断准确性很高,可以作为诊断口腔颌面部肿瘤颈部淋巴结转移的选择,但在选择时应该充分考虑其诊断费用和安全性。