Reliability of a coordinate system based on anatomical landmarks of the maxillofacial skeleton: an evaluation method for three-dimensional images obtained by cone-beam computed tomography

Objectives  We propose a method for evaluating the reliability of a coordinate system based on maxillofacial skeletal landmarks and use it to assess two coordinate systems. Methods  Scatter plots and 95% confidence ellipses of an objective landmark were defined as an index for demonstrating the stability of the coordinate system. A head phantom was positioned horizontally in reference to the Frankfurt horizontal and occlusal planes and subsequently scanned once in each position using cone-beam computed tomography. On the three-dimensional images created with a volume-rendering procedure, six dentists twice set two different coordinate systems: coordinate system 1 was defined by the nasion, sella, and basion, and coordinate system 2 was based on the left orbitale, bilateral porions, and basion. The menton was assigned as an objective landmark. Results  The scatter plot and 95% ellipse of the menton indicated the high-level reliability of coordinate system 2. The patterns with the two coordinate systems were similar between data obtained in different head positions. Conclusions  The method presented here may be effective for evaluating the reliability (reproducibility) of coordinate systems based on skeletal landmarks.     

Reproducibility of landmark identification in the jaw and teeth on 3-dimensional cone-beam computed tomography images: A preliminary study of tentative methods compared to those based on cephalometric definitions

Objective:To compare the reproducibility of landmark identification on three-dimensional (3D) cone-beam computed tomography (CBCT) images between procedures based on traditional cephalometric definitions (procedure 1) and those tentatively proposed for 3D images (procedure 2).Materials and Methods:A phantom with embedded dried human skull was scanned using CBCT. The acquired volume data were transferred to a personal computer, and 3D images were reconstructed. Eighteen dentists plotted nine landmarks related to the jaws and teeth four times: menton (Me), pogonion (Po), upper-1 (U1), lower-1 (L1), left upper-6 (U6), left lower-6 (L6), gonion (Go), condyle (Cd), and coronoid process (Cp). The plotting reliabilities of the two procedures were compared by calculating standard deviations (SDs) in three components (x, y, and z) of coordinates and volumes of 95% confidence ellipsoid.Results:All 27 SDs for procedure 2 were less than 1 mm, and only five of them exceeded 0.5 mm. The variations were significantly different between the two procedures, and the SDs of procedure 2 were smaller than those of procedure 1 in 21 components of coordinates. The ellipsoid volumes were also smaller for procedure 2 than procedure 1, although a significant difference was not found.Conclusions:Definitions determined strictly on each three sectional images, such as for procedure 2, were required for sufficient reliability in identifying the landmark related to the jaws and teeth.     

Reliability and reproducibility of three-dimensional cephalometric landmarks using CBCT: a systematic review

Objective

: The aim of this study was to review the reliability and reproducibility of 3D-CBCT (cone beam computed tomography) cephalometric landmark identification.

Methods

: Electronic databases (Pubmed, Scopus, Web of Science) were searched for papers published from 1998 to October 2014. Specific strategies were developed for each database, with the guidance of a librarian. Two reviewers independently analyzed the titles and abstracts for inclusion. The articles that met the inclusion and exclusion criteria were selected for full-text reading, and the selected articles went through methodological quality evaluation. After the exclusion of repeated articles, the titles of the remaining ones were read and 1,328 of them were excluded. The abstracts of 173 articles were read, of which 43 were selected, read in full and submitted to the inclusion and exclusion criteria. Fourteen articles or studies with reliable methodology and reproducibility remained. The data were collected, organized into figures and analyzed for determination of the reliability and reproducibility of the three-dimensional cephalometric landmarks.

Results

: Overall, the landmarks on the median sagittal line and dental landmarks had the highest reliability, while the landmarks on the condyle, porion and the orbitale presented lower levels of reliability. Point S must be marked in the multiplanar views associated with visualization in 3D reconstruction. Further studies are necessary for evaluating soft tissue landmarks.     

Reliability of different three-dimensional cephalometric landmarks in cone-beam computed tomography: A systematic review

Objectives:Conventional two-dimensional (2D) cephalometric radiography is an integral part of orthodontic patient diagnosis and treatment planning. One must be mindful of its limitations as it indeed is a 2D representation of a vaster three-dimensional (3D) object. Issues with projection errors, landmark identification, and measurement inaccuracies impose significant limitations, which may now be overcome with the advent of cone-beam computed tomography (CBCT). A systematic review of the reliability of different 3D cephalometric landmarks in CBCT imaging was conducted.Materials and Methods:Electronic database searches were administered until October 2017 using PubMed, MEDLINE via OvidSP, EBMR and EMBASE via OvidSP, Scopus, and Web of Science. Google Scholar was used as an adjunctive search tool.Results:Thirteen articles considering CBCT scans of human subjects from preexisting data sets were selected and reviewed. Most of the studies had methodological limitations and were of moderate quality. Because of their heterogeneity, key data from each could not be combined and were reported qualitatively. Overall, in 3D, midsagittal plane landmarks demonstrated greater reliability compared with bilateral landmarks. A minimum number of dental landmarks were reported, although most were recommended for use.Conclusions:Further research is required to evaluate the reliability of 3D cephalometric landmarks when evaluating 3D craniofacial complexes.     

Comparison of in vivo 3D cone-beam computed tomography tooth volume measurement protocols

Background

The objective of this study is to analyze a set of previously developed and proposed image segmentation protocols for precision in both intra- and inter-rater reliability for in vivo tooth volume measurements using cone-beam computed tomography (CBCT) images.

Methods

Six 3D volume segmentation procedures were proposed and tested for intra- and inter-rater reliability to quantify maxillary first molar volumes. Ten randomly selected maxillary first molars were measured in vivo in random order three times with 10 days separation between measurements. Intra- and inter-rater agreement for all segmentation procedures was attained using intra-class correlation coefficient (ICC).

Results

The highest precision was for automated thresholding with manual refinements.

Conclusions

A tooth volume measurement protocol for CBCT images employing automated segmentation with manual human refinement on a 2D slice-by-slice basis in all three planes of space possessed excellent intra- and inter-rater reliability. Three-dimensional volume measurements of the entire tooth structure are more precise than 3D volume measurements of only the dental roots apical to the cemento-enamel junction (CEJ).     

锥形束CT三维图像上标志点可靠性的研究

目的 探讨锥形束CT三维图像中标志点定位的可靠性,以期为建立基于锥形束CT的三维头影测量方法提供依据.方法 选择二维头影测量中常用的39个标志点,4名正畸学专业研究生分别对18例正畸患者的锥形束CT资料进行标志点定位,使用SimPlant软件输出每个标志点的三维坐标,使用组内相关系数（intraclass correlation coefficients,ICC）计算每个标志点在每个维度的可靠性.结果 32个标志点三维方向的ICC＞0.9,7个标志点有一个维度0.8＜ICC＜0.9,其他两个维度的ICC＞0.9.结论 本项研究测量的39个标志点中,32个标志点三维方向可靠性高,可以根据这些标志点来进行三维头影测量.     

成人颜面不对称患者颌面部骨性结构的三维立体分析

目的:通过锥体束CT(cone-beam computerized tomography,CBCT)资料分析颜面不对称患者颌面部骨性结构三维空间位置的改变。方法:对25例成人颜面不对称患者使用CBCT采集颅面部Dicom数据,使用Mimics 10.01对骨组织进行三维重建,并建立三维坐标系。选择描述上颌复合体及下颌骨形态的36个标志点,测量其三维坐标进行统计分析。结果:上颌复合体仅眶下点、梨状孔最外侧点、颧牙槽嵴点、上尖牙颈缘中点、上第一恒磨牙颈缘中点的位置左右侧差异有显著性,其它各点基本对称;下颌骨大部分标志点左右侧在三维方向上均差异显著,仅髁突顶点、下颌孔、下颌角点在某些方向显示出对称性。结论:颜面不对称患者颌面部畸形程度有从上到下逐步加重的趋势,主要表现为下颌骨形态异常,其立体空间结构发生了代偿性的旋转。     

Experimental and clinical assessment of three-dimensional cephalometry: A systematic review

ObjectivesThis study provides a systematic review of the current scientific literature on three-dimensional (3D) cephalometry. The null hypothesis was that 3D cephalometry is an accurate and reproducible diagnostic technique. To examine this hypothesis, the following three research questions were proposed: 1) What is the accuracy of 3D cephalometric measurements compared to in vitro measurements? 2) What is the intra- and inter-observer reliability of the selection of 3D cephalometric landmarks? 3) What is the reproducibility of the linear and angular measurements?MethodsA comprehensive database search was performed, using Medline, the Cochrane Central Register of Controlled Trials, Web of Science and Google Scholar. The titles and abstracts obtained from the search were screened and evaluated by two observers according to the inclusion and exclusion criteria.ResultsThe evaluation process yielded 21 articles. A high level of agreement (<1 mm) between the in vitro measurements and those obtained from 3D cephalometry was observed and some landmarks provided highly reproducible results. However, the linear (0.04–7.49 mm) and angular (0.99–9.30°) measurements differed greatly.ConclusionsThe null hypothesis was rejected. This study indicates critical points regarding 3D cephalometry and provides guidance for future research in this field.     

Stability of fiducial cephalometric landmarks of growing Class II malocclusion patients: a three-dimensional retrospective study

ObjectivesTo evaluate three-dimensionally (3D) the stability of Nasion (Na), Sella (S), Basion (Ba), Porion (Po), and Orbitale (Or) in different age groups of growing Class II malocclusion patients and, additionally, to assess rotational changes of the S-Na and Ba-Na lines and the Frankfurt Horizontal Plane (FHP).Materials and MethodsCone-beam computed tomography studies of 67 Class II division 1 malocclusion patients, acquired at baseline (T0) and 1 year later (T1), were retrospectively assessed. Anterior cranial fossa was used for volumetric superimposition. Subjects were grouped according to their age at T0: group 1 (G1) (8–10 years), G2 (11–13 years), and G3 (14–17 years). Quantitative assessments of the 3D linear displacements (Euclidean distance) in the position of Na, S, Ba, Po, and Or were performed. Displacement in the X, Y, and Z projections and the rotation of S-Na, Na-Ba, and FHP were also quantified.ResultsAll cephalometric landmarks showed 3D displacement (P = .001) in the three age groups. Orbitale remained stable in the vertical and sagittal dimension from 8 to 17 years (P > .05). S-Na, Na-Ba, and the FHP showed statistically significant angular rotation (P < .05) in younger patients (G1), while in older individuals (G2 and G3) they were stable (P > .05).ConclusionsNa, S, Ba, and Po showed vertical and sagittal positional changes relative to the anterior cranial fossa during the growth of Class II individuals. After age 11, S-Na, Na-Ba, and FHP did not show rotation and, thus, are valid parameters for angular cephalometric analysis in Class II growing patients.     

上颌反复快速扩缩前方牵引效果的锥形束CT观察

目的 使用锥形束CT比较上颌单次快速扩弓前方牵引和上颌反复快速扩缩前方牵引的矫治效果,以期为临床提供参考.方法 选择24例上颌后缩患者,使用随机化区组设计的方法分为对照组和反复扩缩组,每组12例.对照组上颌单次快速扩弓后行面罩前方牵引;反复扩缩组上颌反复快速扩缩后行面罩前方牵引.对每组治疗前后的锥形束CT影像进行三维重建、定点、重叠和测量分析.结果 反复扩缩组1例患者在治疗中失访.治疗后反复扩缩组上颌骨前移量[(2.5±1.0)mm]显著大于对照组[(1.6±0.8)mm](P＜0.05);反复扩缩组颅底点至上齿槽座点(Ba-A)的距离增加了(3.1±1.0) mm,显著大于对照组[(2.2±0.9)mm](P＜0.05);反复扩缩组上颌双侧第一磨牙前移量显著大于对照组(P＜0.05).结论 与上颌单次快速扩弓相比,上颌反复快速扩缩前方牵引早期治疗上颌后缩患者可能对上颌骨前移略有利.     

健康成人下颌切牙管的锥形束CT测量分析

目的 利用锥形束CT测量下颌切牙管(mandibular incisive canal,MIC),了解其形态和特点,为临床提供参考.方法 观察2011年1月至2013年1月50名成人健康志愿者的锥形束CT图像,测量分析MIC的检出率、管径、长度及其与颌骨的关系.结果 在50例(100侧)锥形束CT图像中:MIC的检出率为100％(100/100),清晰率为71％(71/100);MIC的管径面积(唇舌径×垂直径)从起点至终点逐渐变小(左侧起点2.17 mm× 2.22 mm,终点0.82 mm× 0.92 mm;右侧起点2.14 mm×2.08 mm,终点0.87 mm×0.86 mm);MIC左右侧平均长度分别为17.84和17.73 mm;MIC在下颌骨唇舌向偏唇侧;在垂直方向MIC距下颌骨下缘较近,MIC到根尖的距离在尖牙最小.结论 锥形束CT对MIC有良好的检出率和清晰率;MIC在下颌骨的走行中偏向唇侧和下颌骨下缘.     

Effect of root canal filling materials on dimensions of cone-beam computed tomography images

Objective

To evaluate the discrepancy of root canal filling (RCF) measurements obtained from original root specimens and cone-beam computed tomography (CBCT) images.

Material and Methods

Seventy-two human maxillary anterior teeth were prepared up to an ISO #50 K-File 1 mm short of the apical foramen. Thus, the teeth were randomly divided into 8 groups, according to the root canal filling material: Sealapex^®, Sealapex^®+gutta-percha points, Sealer 26^®, Sealer 26^®+gutta-percha points, AH PlusTM, AH PlusTM+gutta-percha points, Grossman Sealer, and Grossman Sealer+gutta-percha points. After root canal preparation and RCF, CBCT scans were acquired and the specimens were sectioned in axial, sagittal and coronal planes. The RCF measurements were obtained in different planes and thicknesses to determine the discrepancy between the original root specimens (using a digital caliper) and the CBCT images (using the scanner''s proprietary software). One-way analysis of variance and Tukey tests were used for statistical analyses. The significance level was set at α=5%.

Results

Measurements of the different endodontic filling materials were 9% to 100% greater on the CBCT images than on the original root specimens. Greater RCF dimensions were found when only sealers were used, with statistically significant difference among the groups.

Conclusions

RCF dimensions were greater on CBCT images than on the original root specimens, especially when only sealer was used.     

Integration accuracy of craniofacial cone-beam computed tomography images with three-dimensional facial scans according to different registration areas

ObjectivesTo evaluate the integration accuracy of cone-beam computed tomography (CBCT) images with three-dimensional (3D) facial scans according to different registration areas.Materials and MethodsTwenty-five patients (14 males and 11 females), with a mean age of 19.0 ± 11.3 years, were included in this study. Each patient underwent CBCT and facial scans on the same day in an upright position. The facial scans were integrated with the corresponding soft-tissue images of CBCT scans. Three methods were used to integrate the two imaging modalities based on the facial regions scanned: R1, only the forehead and nasal bridge area were included; R2, the right and left malar area were included; and R3, the forehead, nasal bridge, and malar areas were included. The integration accuracy between the facial scans and CBCT images was evaluated by color-mapping methods and average surface distances, calculated by measuring the 3D distances between the surface points on the two superimposed images.ResultsThe average surface differences between facial scans and CBCT images were less than 1.0 mm in all three methods. The R3 method showed fewer differences between the facial scans and CBCT images than the other methods did.ConclusionsFacial scans obtained using a low-cost facial scanner showed clinically acceptable performance. The integration accuracy of facial and CBCT scans can be increased by including the forehead, nasal bridge, and malar areas as registration areas.     

锥形束CT扫描测量不同矢状骨面型青少年上颌窦大小

目的 利用锥形束CT(CBCT)比较Ⅰ、Ⅱ、Ⅲ类矢状骨面型青少年患者上颌窦大小的差异,探讨上颌窦大小与颅面部骨骼形态的关系.方法 将60例12～16岁的青少年患者按ANB角大小分为Ⅰ、Ⅱ、Ⅲ类三种矢状骨面型组,每组男、女各10例,垂直骨面型皆为均角型.患者接受颅面部CBCT扫描,对上颌窦的长度、宽度、高度、截面积及容积进行测量分析,比较三组间的差异.以CBCT生成的头颅侧位片测量分析颌面部骨骼形态,对上颌窦大小与颌面部骨骼形态的相关性进行研究.结果 不同矢状骨面型青少年患者的上颌窦长度、高度、宽度、截面积和容积的差异具有统计学意义.上颌窦容积Ⅱ类大于Ⅰ类,Ⅱ类大于Ⅲ类.上颌窦容积与前颅底长、全颅底长、ANB角、上中切牙一前鼻嵴点距离及前上面高呈正相关关系,与SNB角呈负相关关系.结论 Ⅱ类骨面型患者具有较大的上颌窦容积,青少年患者上颌窦大小与上下颌骨的矢状关系及颅底长度有一定的相关性.     

上颌切牙根尖周炎骨病损的锥形束CT三维分析

目的 利用锥形束CT对上颌切牙慢性根尖周炎的骨质破坏进行三维结构分析,以期揭示上颌切牙慢性根尖周炎骨质破坏的立体形貌.方法 对临床确诊为慢性根尖周炎的33颗上颌切牙进行锥形束CT扫描,从轴位、矢状位和冠状位图像上测量根尖周骨质缺损切龈向、近远中向和唇腭向的最大径,同时观察骨皮质是否有破坏.结果 33颗上颌切牙根尖周骨病损切龈向骨质破坏最严重,且52％ (17/33)的患牙位于唇、腭侧;61％ (20/33)的患牙唇腭向骨质破坏的最大径大于近远中向骨质破坏的最大径;39％(13/33)的患牙骨皮质有破坏,多发生在唇侧.结论 患慢性根尖周炎的上颌切牙骨质破坏可能更多发生于切龈向和唇腭向,在临床上应加以注意.     

Evaluation of mandibular volume classified by vertical skeletal dimensions with cone-beam computed tomography

Objective:To investigate the relationship between anteroposterior and vertical differences in maxillofacial morphology and mandibular volume.Materials and Methods:Subjects comprised 213 Japanese adults (84 males and 129 females) who were divided into three groups based on mandibular basal arch (ANB) and Wits, measured in a cephalometric analysis: Class I (−1° ≤ ANB < 4°,−1 mm ≤ Wits < 0 mm), Class II (ANB ≥ 4°, Wits ≥ 0), and Class III (ANB <−1°, Wits <−1 mm). Subjects were also divided into three groups based on the mandibular plane angle (Mp), as follows: hypodivergent (Mp < 23°), normodivergent (Mp  =  23–30°), and hyperdivergent (Mp > 30°) groups. Mandibular volume was measured from cone-beam computed tomographic images that were analyzed using Analyze™ image processing software and compared among the three groups in each classification.Results:No significant differences were noted in mandibular volume among Classes I, II, and III. An inverse relationship was found between mandibular volume and Mp, and a significant difference was noted in mandibular volume between the hypodivergent and hyperdivergent groups.Conclusions:In addition to two-dimensional analysis, such as lateral cephalometry, three-dimensional information such as volume, provided by cone-beam computed tomography, contributes to a more detailed assessment of maxillofacial morphology.     

应用锥形束CT分析上颌前牙区龈乳头形态的初步研究

目的 探索上颌前牙区龈乳头充满牙间接触点根方楔形间隙时(以下简称龈乳头充满)的特点及相关因素.方法 选择牙龈健康的北京大学口腔医学院在读学生15人,共纳入62个龈乳头,进行印模技术结合造影间接牙龈显影的锥形束CT拍摄后测量骨嵴顶处的龈乳头高度及厚度,临床测量龈乳头宽度,应用SPSS16.0统计软件分析其相互关系.结果 自然人群中上颌前牙区健康牙龈乳头充满时骨嵴顶处的龈乳头高度为(3.67 ±0.51) mm(均＜5 mm);龈乳头厚度为(8.38±0.75) mm;龈乳头宽度为(4.35±1.03) mm.中切牙与侧切牙间骨嵴顶处龈乳头厚度为(7.97±0.56) mm,与中切牙间及侧切牙与尖牙间的龈乳头厚度差异均有统计学意义(P＜0.05).龈乳头充满时骨嵴顶处的龈乳头高度与厚度呈中度正相关(r=0.433,P＜0.001).结论 应用锥形束CT拍摄能获得龈乳头的清晰影像并可测量其相关指标,牙龈健康的自然人群上颌前牙区龈乳头充满时骨嵴顶处龈乳头高度均＜5 mm;骨嵴顶处龈乳头高度、厚度、宽度两两相关.     

单侧有多种症状的颞下颌关节紊乱患者双侧关节锥形束CT对比研究

目的:探讨单侧有多种症状的颞下颌关节紊乱(temporomandibular disorders,TMD)患者双侧颞下颌关节(temporomandibular joint,TMJ)在锥形束CT(cone-beam computed tomography,CBCT)成像上可能存在差异的参考层面,为TMD诊断和对比研究提供参考.方法:选取仅一侧TMJ有多种症状的TMD患者(不含仅有一种症状的病例)50例,通过CBCT三维成像和重建,观察比较同一患者两侧TMJ重建后横断面的水平角;平行于髁突长轴的斜位关节间隙、髁突长轴径值、髁突垂直角;垂直于髁突长轴的斜位与矢状位的关节结节斜度、关节窝深度和关节间隙,采用SPSS 13.0软件包对每例患者上述各测量指标进行两配对样本t检验.结果:两侧TMJ在矢状位60°关节间隙时的测量值差异显著(P＜0.05),平行位120°关节间隙、矢状位90°关节间隙时的测量值差异显著(P＜0.01),其余测量值均无显著差异.结论:对于单侧有多种症状的TMD患者,矢状位或垂直位是较易观察到两侧关节有差异的位置,在这一层面重建意义较大.     

Evaluation of a novel palatal suture maturation classification as assessed by cone-beam computed tomography imaging of a pre- and postexpansion treatment cohort

Objectives:To test the reliability and usefulness of the midpalatal suture maturation classification and methodology proposed in 2013 by Angelieri et al. for successful prediction of rapid maxillary expansion (RME) treatment results.Materials and Methods:Reliability testing focused on 16 patients aged 9.5–17 years with early mixed to full permanent dentition, representing all proposed palatal maturation stages, from available preexpansion cone-beam computed tomography (CBCT). A retrospective observational longitudinal (cohort) study evaluated 63 preadolescent and adolescent patients aged 11–17 years with full permanent dentition treated with tooth-borne RME appliances who had CBCT records taken at pre- (T₁) and postexpansion (T₂). CBCT three-dimensional landmarking produced skeletal and dental widths and dental angulations used to evaluate the extent of skeletal and/or dental expansion. A regression model was used to assess the prediction capability of the T1 palatal suture classification of each subject for dental and skeletal changes.Results:There was almost perfect intraexaminer agreement and slight to poor interexaminer agreement, differing from previously reported reliability, affected by necessary operator calibration and the degree of postacquisition image sharpness and clarity. Further exploration of its scientific basis suggested that the proposed classification was ill-founded. Results from the cohort study were also wholly unsupportive of efficacy of the proposed palatal suture maturation classification in predicting the magnitude of portrayed changes.Conclusions:Clinicians should be cautious in applying this classification. Although it has merits, the palatal classification still needs much more research and validation.     

Endodontic management of a maxillary first molar with eight root canal systems evaluated using cone-beam computed tomography scanning: a case report

Introduction

Root canal treatment of maxillary molars presenting with complex root canal configurations can be diagnostically and technically challenging.

Methods

Nonsurgical endodontic therapy of a left maxillary first molar with three roots and eight root canals was successfully performed. This unusual morphology was diagnosed using a dental operating microscope (DOM) and confirmed with the help of cone-beam computed tomography (CBCT) images.

Results

CBCT axial images showed that both the mesiobuccal and distobuccal root contained a Sert and Bayirli type XV canal, whereas the palatal root showed a Vertucci type II canal configuration.

Conclusions

The use of a DOM and CBCT imaging in endodontically challenging cases can facilitate a better understanding of the complex root canal anatomy, which ultimately enables the clinician to explore the root canal system and clean, shape, and obturate it more efficiently.