3D Cephalometric Measurements Research Articles

Comparison of Computed Tomography Assisted 3D Cephalometric Measurements in Straight Egyptian Arabian and Thoroughbred Horses.

Dental malocclusions are commonly encountered in horses. The objective of this study was to report the normal cephalometric values from skull computed tomography (CT) scans of adult Straight Egyptian Arabian (SEAR) and thoroughbred (TB) horses and to compare differences in the measurements between the two breeds. Standing skull CTs were performed on 29 clinically normal adult horses (15 SEAR; 14 TB) and cephalometric measurements were taken. All 9 cephalometric measurements, as well as the interincisal angle, were found to be significantly greater in TB than SEAR (P < 0.05). TB were found to have significantly greater facial line: mandibular length (FL/ML) ratios compared to SEAR (P = 0.002) whereas for the maxillary cheek teeth length: ethmoidal line ratio (Mxa/EtL), SEAR were found to have significantly greater values than TB (P = 0.0007). SEAR cephalometric measurements, as well as certain ratios, differ significantly from TB and could have an impact on the development of dental malocclusions in this breed. Further investigation is needed to ascertain whether these cephalometric differences between the two breeds predispose the SEAR to the development of dental malocclusions.

Cross Sectional Analysis of Eurasian Skull Anatomy for 3D Cephalometry-Normative Data Reveal Four Different Skull Types.

The unsolved problem in three-dimensional surgical planning for patients with facial deformity, dysgnathia, or asymmetry is the lack of a normative database of "norm skulls" that can be used as treatment objectives. A study was conducted on 90 Eurasian persons (46 male and 44 female adults) for whom cone beam-computed tomography images were available. Inclusion criteria were adult patients with a skeletal Class I pattern, proper interincisal relationship with normal occlusion, the absence of an open bite both in the anterior and posterior region, and a normal and balanced facial appearance; patients with dysgnathia and malformations were excluded. A total of 18 landmarks were digitized and 3D cephalometric measurements were performed and analyzed by means of proportions calculated from the landmarks. Male and female skulls were analyzed, as well as subdivisions revealed by cluster analysis. The data showed that four subtypes of skulls were distinguishable with statistical significance (p < 0.05). A male and a female type subdivided in a brachiocephalic and dolichocephalic phenotype could be identified. For each type, a mean shape was calculated by a Procrustes transformation, which, in turn, was used to create four template skulls from a male and a female skull. This was accomplished by fitting the polygon models of the two skulls to each of the two subtypes based on the landmarks marked on them using a thin plate spline transformation. The normative data of the subtypes can individually serve as a guide for orthodontic surgery in the Eurasian population, which is especially helpful in 3D planning and the execution of craniofacial operations.

A three-dimensional cephalometric analysis of Japanese adults and its usefulness in orthognathic surgery: A retrospective study

This study aimed to establish a three-dimensional (3D) cephalometric analysis of craniofacial morphology and discuss its theoretical usefulness in orthognathic patients.Cone-beam computed tomography (CBCT) images of Japanese subjects with skeletal Class I malocclusion before treatment were selected from among 1000 patients so that samples matched a historic 2D cephalometric cohort with normal occlusion using propensity score matching. In each CBCT image, 67 3D measurements were calculated based on manually identified landmarks. The mean and standard deviation of the measurements were calculated and used as the normative range for each sex. To confirm the usefulness of the 3D measurements, pre- and post-treatment CT data of nine jaw deformity patients who underwent orthognathic surgery with two-dimensional planning (2DP) in the past were used. Pre- and post-treatment CT values were evaluated with a paired t-test as well as a Z-score, which was calculated using the aforementioned normative range, and then categorized into five groups (“deteriorated”, “no improvement”, “over-treatment”, “no change”, “improvement”) with −1 < Z-score < 1 considered normal.Fifty-six patients were matched to normal skeletal 1 subjects. The normative range of 67 items indicating 3D craniofacial morphology of the Japanese was calculated. Postoperatively, the horizontal position of the pogonion to the mid-sagittal plane significantly decreased (p = 0.043) and “improved”; however, the ramus axis on the right side significantly increased (p = 0.005) and “deteriorated”. Maxillary yaw and the horizontal position of the gonion also tended to “deteriorated”.The normative range for the 3D cephalometric analysis in Japanese has been established. Given findings of deteriorated maxillomandibular yawing after surgery when using conventional 2DP, 3D cephalometric measurements should be used when planning jaw positions after surgery for orthognathic patients.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome.

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion. Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis. Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest’s Craniofacial Imaging Database (WFCID). Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery. None 2D and 3D cephalometric measurements. 3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = −398.75; P &lt; .05) and petrous-occipital (β = −727.5; P &lt; .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = −14 723.1; P &lt; .001) and occipitomastoid synchondrosis (β = −16 419.3; P &lt; .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = −673.3; P &lt; .001), anterior intraoccipital synchondrosis (β = −368.47; P &lt; .05), and posterior intraoccipital synchondrosis (β = −6261.42; P &lt; .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion. Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Three-dimensional cephalometry for orthognathic planning: Normative data and analyses

The objective of this study was to create a normative database of 3D cephalometric measurements for adult Chinese in Taiwan to understand the specific features, as well as to provide information for 3-dimensional (3D) orthognathic surgery planning for patients with maxillofacial deformity. A cross-sectional study was conducted on 30 male and 30 female adults with normal and balanced facial appearance, skeletal Class I pattern, and proper interincisal relationship with normal occlusion. Cone-beam computed tomography was performed. After standard orientation of the 3D image models, 51 landmarks were digitized and 3D cephalometric measurements of overall facial features, midface, maxilla, mandible, dentoalveolus, and soft tissue were performed and analyzed. Reliability and reproducibility of the 3D measurement were achieved. The data showed significant differences between males and females in facial height ratio, midface prominence, midface and maxilla width, mandible width and length for the skeleton, lower incisal inclination and interincisal angle for the dentoalveolus, and lip height, facial height and chin throat angle for the soft tissue. These dataset presented specific facial characteristics of the Chinese face as compared with other populations. The normative data helps to serve as a guide for maxillofacial treatment for globally ethnic Chinese, particularly useful for orthodontic treatment, 3D planning of orthognathic surgery and outcome assessment. Gender and ethnic differences need to be taken into consideration.

Three-dimensional cephalometric norms of Turkish Cypriots using CBCTimages reconstructed from a volumetric rendering program in vivo.

The aim of this study was to create a database of 3D cephalometric measurements of Turkish Cypriot patients using a 3D rendering software program. The study population comprised 121 subjects who had undergone cone beam CT imaging (CBCT). Invivo 5.1 software was used to generate cephalograms from the CBCT dataset that were then linked to the 3D hard-tissue surface representations. In total, 38 angular and 28 linear widely used measurements were recorded. The results demonstrated that males had significantly larger mean values than females for all linear measurements, except for dentoalveolar parameters (P < 0.05). Additionally, significant differences were found in most of the mandibular anteroposterior and vertical measurements, especially SNB, GoGn/SN, FMA, and MP/SN, between the sexes (P < 0.05). This is the first population-based study to focus solely on Turkish Cypriots' craniofacial anatomy and orthodontic characteristics. The present findings will produce 3D cephalometric normative data for the Cypriot population and will be valuable for oral and maxillofacial surgeons and orthodontists in Cyprus, the UK, Australia, Turkey, and other European countries who treat a large number of Turkish Cypriot patients.

Accuracy of 3D cephalometric measurements based on an automatic knowledge-based landmark detection algorithm.

To evaluate the accuracy of three-dimensional cephalometric measurements obtained through an automatic landmark detection algorithm compared to those obtained through manual identification. The study demonstrates a comparison of 51 cephalometric measurements (28 linear, 16 angles and 7 ratios) on 30 CBCT (cone beam computed tomography) images. The analysis was performed to compare measurements based on 21 cephalometric landmarks detected automatically and those identified manually by three observers. Inter-observer ICC for each landmark was found to be excellent ([Formula: see text]) among three observers. The unpaired t-test revealed that there was no statistically significant difference in the measurements based on automatically detected and manually identified landmarks. The difference between the manual and automatic observation for each measurement was reported as an error. The highest mean error in the linear and angular measurements was found to be 2.63mm ([Formula: see text] distance) and [Formula: see text] ([Formula: see text]-Me angle), respectively. The highest mean error in the group of distance ratios was 0.03 (for N-Me/N-ANS and [Formula: see text]). Cephalometric measurements computed from automatic detection of landmarks on 3D CBCT image were as accurate as those computed from manual identification.

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.

A 3D computerized tomography study of changes in craniofacial morphology of Portuguese skulls from the eighteenth century to the present

This study examined the three-dimensional (3D) changes in craniofacial morphology between 482 identified Portuguese skulls from the eighteenth to the twentieth centuries and 150 modern Portuguese individuals randomly selected from the armed forces. The goal was to investigate the interrelationship between changes in various parts of the skull, in particular, the cranial base, the brain supporting structures, and the face. Cone beam computed tomography images from the identified skull collections belonging to the Department of Life Sciences at the University of Coimbra and Natural History National Museum of Lisbon were used. These 3D images from craniometric analyses included 19 different linear, angular, and orthogonal 3D measurements. The trend in horizontal position of the maxilla (SNA) and horizontal position of the mandible (SNB) angles showed a significant increase, while the relative position of the maxilla to mandible (ANB) and the global angle mean values decreased over time. Skulls from each subsequent century demonstrated a decrease in anterior cranial base, indicated by the mean distance between S and N landmarks. Significant negative correlations were found between SNA and anterior cranial base length (S-N). The negative correlations between SNB and anterior cranial base length (S-N) decreased from the eighteenth to nineteenth centuries. The twenty-first century skulls were characterized by a significant difference in the mean value of different craniofacial variables between males and females. The results of this study suggest changes in the 3D cephalometric measurements of craniofacial architecture. These changes are highly integrated, and show an interesting correlation between structures of the craniofacial facial complex and the anterior cranial base.

Reliability and the smallest detectable difference of measurements on 3-dimensional cone-beam computed tomography images

The aim of this study was to determine the reliability and the measurement error (by means of the smallest detectable error) of 17 commonly used cephalometric measurements made on 3-dimensional (3D) cone-beam computed tomography images. Twenty-five cone-beam computed tomography scans were randomly selected, and 3D images were rendered, segmented, and traced with the SimPlant Ortho Pro software (version 2.1, Materialise Dental, Leuven, Belgium). This was repeated twice by 2 observers during 2 sessions at least 1 week apart. Measurement error was determined by means of the smallest detectable difference. Differences were analyzed with Wilcoxon signed rank tests. Intraobserver and interobserver reliability values were calculated by means of intraclass correlation coefficients (ICC) based on absolute agreement. There were great variations of measurement errors between the angular (range, 0.88°-6.29°) and linear (range, 1.33-3.56 mm) variables. The greatest measuring error was associated with the dental measurements U1-FHPL, L1-MdPL. and L1-FHPL (range, 3.80°-6.29°). ANB angle was the only variable with a measuring error of 1° or less for both observers. The intraobserver agreement of all measurements was very good (ICC, 0.86-0.99). Except for SN-FHPL (ICC, 0.76), interobserver agreement was very good (ICC,>0.88). The measurement errors of 3D cephalometric measurements (except for the ANB angle) can be considered clinically relevant. This questions the use of linear and angular 3D measurements to detect true treatment effects when a high level of accuracy is required.

Three-dimensional cephalometric norms of Chinese adults in Hong Kong with balanced facial profile

The objectives of this study were (1) to develop a 3D cephalometric analysis scheme applicable to assessing dentofacial deformities; and (2) to create a normative database of 3D cephalometric measurements for adult Chinese in Hong Kong. A cross-sectional study was conducted on 50 male and 50 female adults with normal balanced facial profile and occlusion. Cone-beam computed tomography and stereo photogrammetry imaging were performed on all subjects. Three-dimensional virtual models were generated from imaging data, and cephalometric analysis was performed using specialized software. A new 3D cephalometric analysis scheme appropriate for orthognathic surgery as well as a new reference plane (supraorbital margin plane) for midfacial assessment was used in this study. The cephalometric norms generated in this study were comparable with those reported in the literature for conventional 2D cephalometric analysis and the unique features of Chinese faces. The results also showed significant differences between males and females in most of the facial height measurements (P < .01). This is the first database of 3D cephalometric norms based on CBCT and 3D photogrammetry of the Chinese population in Hong Kong. This can be a useful reference for characterizing facial deformities in 3 dimensions. Moreover, 3D cephalometric analysis has the potential of incorporating new measurement methods that are difficult if not impossible in 2D cephalometric analysis.

Measurement accuracy of a computer-assisted three-dimensional analysis and a conventional two-dimensional method

To determine the differences between manual and cephalometric measurements on different sections of the human skull, which were obtained using computer-assisted three-dimensional (3D) analysis and conventional two-dimensional (2D) techniques. Measurements were carried out on 13 dry human skulls, then 2D cephalograms and 3D computed tomographic (CT) images were obtained. Anatomic landmarks were determined and marked with clay before CT images were taken, and the same landmarks were marked with the help of metallic balls and pins for lateral and frontal cephalograms. Manual, lateral/frontal cephalometric, and computer-assisted 3D cephalometric measurements were compared statistically. One-way analysis of variance and Tukey Honestly Significant Difference tests were used to compare the results among the groups. All measurements were statistically insignificant between the computer-assisted 3D and manual measurements. On the other hand, the differences between the conventional 2D and the manual measurements were statistically significant. The greatest amount of magnification was found at the Nasion-Menton distance (14.6%), which was located at the farthest distance from the central x-ray beam in the lateral cephalogram (P < .01). For the same reason, the greatest enlargement (16.2%) was observed in the distance between the zygomaticomaxillary sutures on the conventional frontal cephalogram (P < .01). The computer-aided 3D cephalometric measurements were found to be more accurate than the conventional cephalometric measurements. The results revealed that 3D cephalometric measurements were consistent with the manual measurements. In addition, the magnification and distortion might limit the results of conventional cephalometric measurements.

Three-dimensional CT analysis of vomer bone in the architecture of craniofacial structures in caucasic human skulls

INTRODUCTION: The craniofacial architecture is the result of a very complex interrelation. The nasal septum and specially vomer bone, because of its strategic spatial location between the cranial base and the mid-face, influence the growth of this area of the facial skeleton, thus playing a major role in the organization of the craniofacial architecture. The purpose was to analyze the influence of vomer bone on the morphology of the craniofacial architecture, evaluate its correlation with different structures, and compare the spatial position and dimensions between dentoskeletal frames. METHOD: 3D cephalometric measurements were analyzed and correlated in 302 digitally reconstructed skulls by 3D CBCT of a caucasic European adult population. RESULTS: Changes in the inclination and the dimensions of vomer bone were strongly correlated with other craniofacial structures. There were significant variations in vomer bone between the different dentoskeletal frames. CONCLUSIONS: Vomer bone seems to play an important role in the interrelation of the craniofacial architecture.

S414: Computer-Assisted Planning and Navigation in Craniomaxillofacial Surgery

The combination of medical imaging and rapid prototyping is a rapidly expanding field with a large application potential in craniomaxillofacial reconstructive surgery. Typical applications include the making of three-dimensional models for treatment planning, the production of custom designed prostheses and the replication of segmental anatomical objects to guide the surgeon's reconstructive efforts. When 3D visualization is combined with a 3D surgery simulation and intra-operative navigation it becomes a powerful tool for precise and accurate surgical planning and execution of the treatment plan. Using intuitive, easy to follow steps, the surgeon can evaluate the patient's anatomy, perform 3D cephalometric measurements, segmentation and mirroring, simulate osteotomies and distraction surgeries in 3D. Furthermore, visualization of the surgical plan is a valuable tool to enhance communication between the surgeon and the patient, demonstrating where the bone cuts will be performed and how the segments will be repositioned during surgery. Lastly, based on this plan, surgical cutting guides and “splints” can be produced using RP technologies for an accurate transfer to the surgery.