下颌管分支的锥形束CT影像学分析

目的 运用锥形束CT（CBCT）分析下颌管分支发生的概率及其类型。方法 选取拍摄CBCT影像的216例（女104 例,男112例）患者为研究对象,对CBCT的下颌管分支影像进行观测并进行分类。结果 216例（432侧）患者中,39例（18.06%）50侧（11.57%）观测到下颌管分支,其中女18例（17.31%）,男21例（18.75%）。下颌管分支分为4类,第Ⅰ类17侧（3.94%）,第Ⅱ类11侧（2.55%）,第Ⅲ类20侧（4.63%）,第Ⅳ类2侧（0.46%）。结论 CBCT对下颌管分支的检出率较高,口腔颌面外科医生在进行下颌手术时应注意下颌管分支这一解剖变异。     

根尖周病中锥形束CT与根尖片识别病损差异的研究进展

随着影像学技术的进步,锥形束CT（CBCT）作为口腔临床检查的一种辅助手段,已经广泛应用于口腔医学的各个领域。它具有分辨率高、辐射量低、成像迅速、三维重建、失真小、对硬组织成像好等诸多优点。传统的根尖片是以二维图像的形式显示三维物体及其周围结构,仅显示重叠的近远中向骨质破坏,不能显示颊舌向骨质破坏。CBCT作为一种三维成像技术,可以从矢状位、冠状位和轴位显示组织的三维结构,克服了根尖片二维图像重叠、变形等缺陷。CBCT的三维成像技术较传统根尖片具有独特优势,与根尖片相比,CBCT在观察骨质结构和根尖骨质破坏方面具有更高的灵敏度。本文就CBCT与根尖片在根尖病损识别中的差异研究进展作一综述。     

锥形束CT在牙体牙髓病的临床应用进展

锥形束CT(cone beam computed tomography,CBCT)凭借其三维重组成像、高分辨率等众多优势已广泛应用于口腔临床方面,简化并提高了口腔临床的诊治工作,该文就CBCT在牙体牙髓常见及疑难疾病中的诊断与运用的最新进展作一综述。     

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。     

Texture analysis of cone beam computed tomography images reveals dental implant stability

The aim of this study was to characterize the alveolar bone of edentulous maxillary sites using texture analysis (TA) of cone beam computed tomography (CBCT) images and to correlate the results to the insertion torque, thus verifying whether TA is a predictive tool of final implant treatment. This study was conducted on patients who had received single implants in the maxilla (46 implants) 1 year earlier and whose torque values were properly recorded. Three cross-sections of the sites were selected on CBCT scans. Two regions of interest (ROIs) corresponding to the implant bone site and peri-implant bone were also outlined, according to virtual planning. The CBCT scans were exported to MaZda software, where the two ROIs were delimited following the previously demarcated contours. Values for the co-occurrence matrix were calculated for TA. With regard to the insertion torque value, there was a direct correlation with the contrast of the peri-implant bone (P < 0.001) and an inverse correlation with the entropy of the implant bone site (P = 0.006). A greater contrast indicates a greater torque value for insertion of the implants, and there is a possible association with a lower entropy value of the implant–bone interface.     

锥形束CT的特点及其在正畸专业中的应用

在正畸治疗中,X线检查对明确患者的错袷类型、制定错[牙合]畸形患者的矫治计划等具有重要的价值。长期以来,医生使用的曲面断层片和头颅侧位片,均为二维影像,且存在着重叠、图像放大等缺点。传统的扇形CT,因其占地面积大、设备价格高、操作复杂、射线量大、费用昂贵等因素,无法成为正畸患者常规的检查方法。近年来,随着锥形束CT（CBCT）的引入,对正畸患者的诊断和治疗,以及在医患沟通方面均带来了很大的帮助。本文就CBCT的起源和技术特点及其在正畸专业中的应用作一综述。     

Comparative study of cone beam computed tomography and intraoral periapical radiographs in diagnosis of lingual-simulated external root resorptions

Abstract – Background: Owing to a lack of symptoms and difficult visualization in routine intraoral radiographs, diagnosis of external root resorptions can be challenging. Aim: The goal of this study was to compare two image acquisition methods, intraoral radiographs and cone beam computed tomography (CBCT), in the diagnosis of external resorption. Material and Methods: Thirty‐four maxillary and mandibular bicuspids were divided into three groups. Perforations measuring 0.3 and 0.6 mm in diameter and 0.15 and 0.3 mm in depth, respectively, were made on the lingual root surfaces in thirty teeth, and four were used as controls. Next, teeth were mounted on an apparatus and radiographed at mesial, distal, and orthoradial angulations. CBCT images were also taken. The analysis of the intraoral radiographic and tomographic images was carried out by two experts using standardized scores. Data were then compared statistically. Results: A strong agreement between the examiners was observed in both diagnosis methods, the intraoral radiographic (r = 0.93) and the tomographic analysis (r = 1.0). Tomography had higher statistically significant detection values than intraoral radiography (P < 0.05). In intraoral radiographs, the detection was significantly greater (P < 0.05) in the mandibular bicuspids, compared with their maxillary counterparts. The ability to detect 0.6‐mm perforations by intraoral radiography was significantly higher than that of 0.3‐mm perforations (P < 0.05). Conclusion: Cone beam computed tomography showed better diagnostic ability compared with intraoral radiography, regardless of the tooth or the dimensions of the resorption evaluated.     

Bone quality assessment based on cone beam computed tomography imaging

Objectives: The aim of this in vitro study was to investigate the accuracy of fractal analysis and morphometry for bone quality assessment as measured with dual energy X-ray absorptiometry (DXA).
Material and methods: Nineteen mandibular bone samples were used for the creation of artificial bone lesions ( n =5) or decalcification ( n =12) to simulate osteoporosis; two samples were used as controls. Cone beam computed tomography (CBCT) and DXA scans were made before and after processing the samples. The image data obtained from the CBCT scans were used to calculate the mean fractal dimension (FD), bone area and density (morphometric analysis) of the samples. Bone mineral density (BMD) was obtained from the DXA scans and set as a reference value for bone quality. The correlation between BMD and FD and between BMD and morphometric results were calculated.
Results: A significant correlation between FD and BMD (ρ=+0.71 to +0.75; P <0.05) was observed. Bone area and BMD of the specimens (ρ=+0.69 to +0.85; P <0.05) were also significantly related, in contrast to the density analysis, for which no significant correlation to BMD was found.
Conclusions: The results of this study suggest that fractal analysis and bone area measurement have potential to evaluate bone quality on CBCT images, while density measurement does not seem to be valid.     

锥形束CT用于评价离体牙槽骨高度准确性的研究

目的评价锥形束CT（CBCT）图像测量离体牙槽骨高度的准确性和可重复性,为其应用于牙周病的临床诊断和预后评价提供理论依据。方法使用CBCT对8具干燥下颌骨进行扫描,在图像上重复测量236个人工选择标志点处牙槽嵴顶至釉牙骨质界的距离;同时使用游标卡尺直接测量以上标志点处牙槽嵴顶至釉牙骨质界的距离。应用SPSS 13.0软件对所得数据进行统计学分析。结果CBCT图像对牙槽嵴顶至釉牙骨质界距离的重复测量结果间差异无统计学意义（P>0.05）;CBCT图像与游标卡尺对牙槽嵴顶至釉牙骨质界距离的测量结果间差异也无统计学意义（P>0.05）。结论CBCT图像可清晰显示牙与牙槽骨之间的空间解剖关系,其对牙槽骨高度体外测量的结果具有准确性和可重复性。     

Diagnostic performance of mobile cone beam computed tomography versus conventional multi-detector computed tomography in orbital floor fractures: a study on human specimens

The aim of this study was to evaluate the diagnostic accuracy of mobile cone beam computed tomography (MCBCT) versus multi-detector computed tomography (MDCT) in orbital floor fractures. Twenty-four fresh cadaver heads were used, and one orbital floor was fractured for each head by transconjunctival approach. MDCT and MCBCT were performed on each of the heads. The images obtained were then analysed independently by eight evaluators. The radiological characteristics of the orbital floor fractures were visualized with good interpretation agreement between the two images. The location of the fracture and enophthalmos were identified in a comparable manner with strong agreement (κ = 0.93 and κ = 0.85, respectively). Measurements of fatty hernias and bone defects showed a strong correlation between the two imaging modalities (Pearson coefficient between 0.64 and 0.71 and between 0.67 and 0.71, respectively). The fracture limits and the presence of bone fragments, an intrasinus fatty hernia, and a fracture of the associated medial orbital wall were visualized in both examinations with good agreement (κ = 0.68, κ = 0.51, κ = 0.57, and κ = 0.46, respectively). The soft tissue study showed superiority for MDCT, with a κ < 0.0009. MCBCT showed good diagnostic performance in the study of orbital floor fracture characteristics.     

Branching of mandibular canal on cone beam computed tomography images

BackgroundMandibular neurovascular canal contents may be vulnerable to damage during mandibular surgical procedures. Greater knowledge of the location and configuration of the mandibular canal can help in the safe performance of these procedures in the dental clinic. Cross-sectional CBCT imaging is a good modality for studying the course, location, configuration and accessory branches of the mandibular canal. The aim of this study was to observe the branching of the mandibular canal at different segments of the mandible and mandibular tooth groups.MethodsCBCT images of 116 mandibular halves were included in this study. The presence of secondary branching of the mandibular canal in the ramus, retromolar area, molar and premolar teeth as well as the length, diameter and angle of these branches were observed.Resultssixty nine mandibular halves (59.5%), had a main canal with no branching, There were 36 IAC (31%) with one, 8 (6.9%) with two, 2 (1.7%) with three and 1(0.9%) with 5 accessory branches. Of these secondary branches, 16 (25.4%) were in the ramus, 16(25.4%) in the retromolar, and 31(49.2%) in the molar regions.ConclusionAdvanced cross-sectional imaging modalities especially CBCT is a suitable tool for observing anatomic characteristics of mandibular canal to preserve this vital structure in surgical procedures.     

Cone‐beam computed tomography and the dentist

Although cone‐beam computed tomography (CBCT) is just 15 years old, it has revolutionized the practice of dentistry, so much so, there is hardly a dental specialty which has not been affected by this technology. Nevertheless, it presents the dentist with a number of important challenges. An initial steep learning curve must be addressed without unnecessary exposure to the patient. This is particularly important when the patient is a child.     

应用CBCT回顾分析牙源性上颌窦病变

［摘要］ 目的 通过回顾CBCT资料评估牙源性上颌窦炎的影像学表现及最易引起牙源性上颌窦炎的牙位。方法 将500例CBCT资料分为正常上颌窦、牙源性上颌窦病变、非牙源性上颌窦病变和无法判断来源的上颌窦病变,并进行统计学分析。结果 牙源性上颌窦炎的影像学表现是发生龋病、不良修复体的上颌后牙或对应牙位有未愈合的拔牙创,无论其是否伴有根尖周病变,该病变牙相应上颌窦底黏膜会呈局部隆突性增厚影像。牙源性上颌窦炎发病率占常人的12.4%,占上颌窦病变病人的48.6%。上颌第一磨牙最易引起牙源性上颌窦炎。发生上颌窦炎,即黏膜增厚>2 mm的病例中,黏膜平均增厚(6.11±4.43) mm。结论 牙源性因素占上颌窦炎发病因素的一半;上颌第一磨牙最易引起牙源性上颌窦炎;CBCT能清晰反映上颌窦的解剖解构及上颌窦炎所引起的变化。     

颞下颌关节骨关节病不同分期的锥形束CT三维位置比较

目的 探讨颞下颌关节骨关节病（TMJOA）患者在不同骨关节病分期髁突三维影像学特征的差异。方法 以2005年马绪臣等提出的骨关节病X线表现分期为标准,将108例TMJOA患者（骨关节病组）的锥形束CT（CBCT）检查结果分为4期,对照组为28例仅存在间隙改变的颞下颌关节紊乱病患者;评价TMJOA CBCT征象不同分期时髁突的矢状面位置,并对2组的髁突水平角进行比较。结果 TMJOA不同分期髁突矢状面位置无统计学差异,但髁突水平角有统计学差异（F=3.872,P=0.005）,进一步两两分析表明,第1期髁突水平角低于第2和3期（P=0.027,P= 0.000）;第2期对照组髁突水平角低于第3期（P=0.004,P=0.047）。结论 TMJOA患者在不同分期时髁突矢状面位置差异不明显,但髁突水平角存在差异,该角度的变化对TMJOA的分期有一定提示意义。     

Influence of maxillomandibular positioning in cone beam computed tomography for implant planning

The aim of this study was to evaluate the influence of changes in maxillomandibular positioning during cone beam computed tomography (CBCT) imaging on the planning of dental implants. Ten skulls were marked bilaterally with metal spheres in four regions: incisors, canine, premolars, and molars. CBCT scans were obtained in seven positions: standard position (SP), displacements of 10° and 20° above and below the SP, and lateral displacements of 10° and 20° from the SP. Subsequently, bilateral measurements of the height and width of the maxilla and mandible were performed on all images. The results showed that the position with a displacement of 20° above the SP presented the greatest differences in the measurements of bone height and width. In the bilateral comparisons, the maxillary bone width showed the greatest differences, especially for the regions of the premolars and molars. It is concluded that alterations of positioning during the acquisition of CBCT images can lead to alterations in the measurements of bone height and width, which may result in errors in implant planning and cause damage to anatomical structures.