Evaluation of the validity of the Bolton Index using cone-beam computed tomography (CBCT)

Aims: To evaluate the reliability and reproducibility of calculating the Bolton Index using cone-beam computed tomography (CBCT), and to compare this with measurements obtained using the 2D Digital Method. Material and Methods: Traditional study models were obtained from 50 patients, which were then digitized in order to be able to measure them using the Digital Method. Likewise, CBCTs of those same patients were undertaken using the Dental Picasso Master 3D? and the images obtained were then analysed using the InVivoDental programme. Results: By determining the regression lines for both measurement methods, as well as the difference between both of their values, the two methods are shown to be comparable, despite the fact that the measurements analysed presented statistically significant differences. Conclusions: The three-dimensional models obtained from the CBCT are as accurate and reproducible as the digital models obtained from the plaster study casts for calculating the Bolton Index. The differences existing between both methods were clinically acceptable.     

偏颌畸形患者颅颌面部组织不对称的CBCT研究

目的应用CBCT评估偏颌畸形患者颅颌面部软硬组织不对称的特征。方法选取30例偏颌畸形患者(软组织颏部偏离中线4 mm以上、平均年龄19.5岁)和30例面部基本对称的患者(软组织颏部偏离中线2 mm以内,平均年龄19.9岁)的CBCT原始数据,分别设为实验组和对照组。导入到Mimics 17.0软件程序,进行三维重建。通过在3个维度进行线性距离、角度、体积和表面积的测量,评估和比较组间、组内的差异。结果偏颌畸形患者的左右侧线性、角度、体积、表面积测量等存在统计学差异(P<0.05)。在实验组中,偏差侧和非偏差侧Z-Ag、ZA-Goinf、J-FML、J-N、Golat-Me、Co-Goinf、Gopost-FML、Golat-FML、Gopost-Me、Co-Me、P-N、MOP、MBP和Golat-Me有统计学差异。对照组两侧的J-FML、J-N、Golat-FML有统计学意义。实验组中两侧下颌骨的体积和表面积测量有统计学差异。结论面部不对称主要发生在下颌骨,特别是下颌角区表现明显。利用CBCT精确量化偏颌畸形患者面部软硬组织不对称的结构特征,对于诊断和治疗至关重要。     

Evaluation of mastoid pneumatization using cone-beam computed tomography

Objectives

The goals of this study were to evaluate mastoid pneumatization using a grading system and to assess the prevalences of pneumatization of temporal structures of the temporomandibular joint (TMJ) and their relationships with age and sex using cone-beam computed tomography.

Methods

For this study, 250 randomly selected patient dental volumetric tomography scans contained within the archives of the Department of Dentomaxillofacial Radiology, Gazi University Faculty of Dentistry were retrospectively reviewed, and the degrees of mastoid pneumatization were separately graded for the right and left areas. A grading system was used for pneumatization as follows: grade 0, pneumatization limited to the mastoid process; grade 1, pneumatization between the mastoid process and the glenoid fossa; grade 2, pneumatization between the deepest point of the glenoid fossa and the tip of the articular eminence; grade 3, pneumatization extending beyond the crest of the articular eminence.

Results

Of the 500 investigated areas, 32.4 % had grade 0 pneumatization, 55.4 % had grade 1, 8.6 % had grade 2, and 3.6 % had grade 3. There were no significant correlations between pneumatization grade and age or sex.

Conclusions

Pneumatization of the mastoid process may extend beyond the external earway and include temporal components of the TMJ in a significant group of patients.     

A new 3D method for measuring cranio-facial relationships with cone beam computed tomography (CBCT)

Objectives: CBCT systems, with their high precision 3D reconstructions, 1:1 images and accuracy in locating cephalometric landmarks, allows us to evaluate measurements from craniofacial structures, so enabling us to replace the anthropometric methods or bidimensional methods used until now. The aims are to analyse cranio-facial relationships in a sample of patients who had previously undergone a CBCT and create a new 3D cephalometric method for assessing and measuring patients. Study Design: 90 patients who had a CBCT (i-Cat®) as a diagnostic register were selected. 12 cephalometric landmarks on the three spatial planes (X,Y,Z) were defined and 21 linear measurements were established. Using these measurements, 7 triangles were described and analysed. With the sides of the triangles: (CdR-Me-CdL); (FzR-Me-FzL); (GoR-N-GoL); and the Gl-Me distance, the ratios between them were analysed. In addition, 4 triangles in the mandible were measured (body: GoR-DB-Me and GoL-DB-Me and ramus: KrR-CdR-GoR and KrL-CdL-GoL). Results: When analyzing the sides of the CdR-Me-CdL triangle, it was found that the 69.33% of the patients could be considered symmetric.Regarding the ratios between the sides of the following triangles: CdR-Me-CdL, FzR-Me-FzL, GoR-N-GoL and the Gl-Me distance, it was found that almost all ratios were close to 1:1 except between the CdR-CdL side with respect the rest of the sides. With regard to the ratios of the 4 triangles of the mandible, it was found that the most symmetrical relationships were those corresponding to the sides of the body of the mandible and the most asymmetrical ones were those corresponding to the base of such triangles. Conclusions: A new method for assessing cranio-facial relationshps using CBCT has been established. It could be used for diverse purposes including diagnosis and treatment planning. Key words:Craniofacial relationship, CBCT, 3D cephalometry.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

乳磨牙根管复杂性的CBCT研究

目的 利用CBCT研究上海地区儿童乳磨牙牙根数目及根管系统解剖形态,为临床诊断提供影像学依据.方法 选取167例患者(4～7岁)CBCT扫描图像,测量乳磨牙牙根数目、牙齿长度,分析根管数目和类型,并对相应结果做统计学分析.结果 ①上颌第一乳磨牙牙根中三根占50.30％,双根占47.59％.上颌第二乳磨牙牙根三根检出率99.37％.下颌第一、二乳磨牙牙根以双根居多,分别为91.48％、72.95％.②上颌乳磨牙腭根的牙齿长度较颊根长;下颌第一乳磨牙近、远中根的牙齿长度未见明显差异,下颌第二乳磨牙近中根的牙齿长度较远中根长.③上颌第一乳磨牙根管数目以三根管居多,为97.59％.上颌第二乳磨牙三根管占87.13％,四根管占12.27％.上颌乳磨牙的根管类型为Ⅰ型、Ⅱ型、Ⅲ型和Ⅳ型,以Ⅰ型居多.④下颌第一乳磨牙中三根管占41.96％(近中根管为双根管的占39.10％,远中根管为双根管的占60.90％),四根管为39.75％,双根管18.30％.下颌第二乳磨牙中多为四根管,占83.28％.下颌乳磨牙的根管类型主要是Ⅰ型和Ⅳ型.结论 乳磨牙牙根及根管解剖结构复杂多变、变异率高.上颌第二乳磨牙和下颌第一乳磨牙根管结构变异率较其他牙位高,结合CBCT有利于明确诊断和治疗.     

应用锥形束CT影像对颏管的三维定量测量及临床意义

目的:应用锥形束CT(CBCT conebeam computed tomography)影像对颏管三维结构、走向及毗邻关系进行定量测量,为确保颏孔区域牙种植手术的安全提供依据。方法:对我院门诊口腔科80例患者的160侧下颌骨CBCT影像进行回顾性分析,对颏管的曲面、矢状位、冠状位、水平位及3D影像进行测量分析。结果:曲面和矢状位影像可对下颌管进行全面的观察。水平位影像显示下颌管在下颌骨体部靠近舌侧与下颌骨体平行走行,之后,以23°±5°角偏离舌侧转向颊侧走行,下颌管向颊侧走行与颏管形成的角度为101.76°±18.27°,最终分成切牙管与颏管。冠状位影像测量颏管的长度为8.09±1.06mm,直径为1.68±0.52mm,与下颌骨体下缘所呈的倾斜角为36.48°±8.43°。颏管起始处至牙槽嵴顶的距离16.10±4.29mm。3D侧位影像可清晰显示颏孔位置。结论:CBCT影像可清晰显示颏管的三维结构、走向及毗邻关系,明确了此区域神经、血管的分布及骨组织的状况,为牙种植钉及手术入路的选择提供可靠依据。     

Cone beam computed tomography (CBCT) in endodontics

Cone beam computed tomography (CBCT) is an extra-oral imaging system which produces 3-dimensional scans of the maxillofacial skeleton. It is useful in overcoming the limitations of conventional radiography. CBCT is a valuable aid in providing additional information for diagnosis and enabling more predictable management of complex endodontic problems compared to using intra-oral radiographs alone. CLINICAL RELEVANCE: There are potential indications for the use of CBCT in diagnosis and treatment planning.     

Evaluation of tongue volume and oral cavity capacity using cone-beam computed tomography

The aims of this study were to reveal the usefulness of a newly developed method for measuring tongue volume (TV) and oral cavity capacity (OCC) and to assess the relationship between them. The tongue was coated with a contrast agent, and the TV and OCC were determined using cone-beam computed tomography (CBCT). We enrolled 20 adults who were scheduled to undergo CBCT to evaluate the relationship of the third molar roots to the alveolar nerve before molar extraction. Each participant’s tongue was coated with a contrast agent, and CBCT of the tongue and oral cavity was performed. Using computer software, we evaluated reconstructed 3D images of the TV, oral cavity proper volume (OCPV), and OCC. The mean TV was 47.07 ± 7.08 cm³. The mean OCPV and OCC were 4.40 ± 2.78 cm³ and 51.47 ± 6.46 cm³, respectively. There was a significant correlation between TV and OCC (r = 0.920; p < 0.01) but not between TV and OCPV. The mean TV/OCC ratio was 91 ± 5%. The proposed method produced CBCT images that enabled effective measurement of TV and OCC. This simple method of measuring TV and OCC will be useful in the diagnosis on the tongues with abnormal size.     

基于CBCT对江苏地区人群下颌神经管走向的研究

目的通过锥形束CT(cone beam computed tomography,CBCT)检查分析下颌神经管与下颌骨的位置关系,为避免在外科手术中损伤下牙槽血管神经束提供统计学依据。方法收集90例(男45例,女45例)江苏地区人群(20⁷9岁)下颌骨的CBCT数据,将其导入NNT 4.6软件中,测量下颌神经管在下颌骨中的位置,分析性别和左右侧对其位置的影响。结果由近中向远中,下颌神经管到牙槽嵴顶的平均距离先增大再减小;到下颌骨颊侧的平均距离逐渐增加;两者在男女间和左右侧间的差异都不显著(P>0.05)。下颌神经管到下颌骨下缘和舌侧的平均距离逐渐减小,在颏孔后2 mm处两者在左侧的平均距离小于右侧(P<0.05),且前者在女性左侧的平均距离小于男性(P<0.05)。下颌管距下颌后牙牙根的平均距离由近中向远中逐渐减小,两者在男女间和左右侧间的差异都不显著(P>0.05)。结论江苏地区人群的下颌神经管到牙槽嵴顶和下颌骨颊侧距离男女相似,且左右对称性较好;到下颌骨下缘和舌侧的距离有性别差异,且左右间不太对称;位置在颏孔远中2 mm后相对恒定,在颏孔后2 mm以内的变化较大。     

Evaluation of cone-beam computed tomography diagnostic image quality using cluster signal-to-noise analysis

Oral Radiology - (1) We sought to assess correlation among four representative parameters from a cluster signal-to-noise curve (true-positive rate [TPR] corresponding to background noise, accuracy...     

Accuracy and repeatability of cone-beam computed tomography (CBCT) measurements used in the determination of facial indices in the laboratory setup

AIM: To assess the three dimensional (3D) surface accuracy of a phantom's face acquired from a cone-beam computed tomography (CBCT) scan and to determine the reliability of selected cephalometric measurements performed with Maxilim software (Medicim N.V., Mechelen, Belgium). MATERIAL AND METHODS: A mannequin head was imaged with a CBCT (I-CAT, Imaging Sciences International, Inc., Hatfield, USA). The data were used to produce 3D surface meshes (Maxilim and Mimics, Materialise N.V., Leuven, Belgium) which were compared with an optical surface scan of the head using Focus Inspection software (Metris N.V., Leuven, Belgium). The intra- and inter-observer reliability for the measurement of distances between facial landmarks with Maxilim 3D cephalometry were determined by calculating Pearson correlation coefficients and intraclass correlation (ICC). The Dahlberg formula was used to assess the method error (ME). RESULTS: (1) The maximal range of the 3D mesh deviations was 1.9 mm for Maxilim, and 1.8mm for Mimics segmentation. (2) Test-retest and inter-observer reliability were high; Pearson's correlation coefficient was 1.000 and the ICC was 0.9998. The ME of the vertical measurements was a little larger than that calculated for the width measurements. Maximum ME was 1.33 mm. CONCLUSIONS: The 3D surface accuracy of CBCT scans segmented with Maxilim and Mimics software is high. Maxilim also shows satisfactory intra- and inter-assessor reliability for measurement of distances on a rigid facial surface.