Craniofacial measurements in children with sella turcica shape’s anomalies

Objectives: The objective of the study is to evaluate the cephalometric measurements of Tunisian children who presented sella turcica’s (ST) shape anomalies. Materials and Methods: This cross-sectional study was conducted between January and June 2019 in the Department of Pediatric Dentistry of Monastir and Faculty of Dentistry of Tunisia. Radiographs were gathered from patients aged between 7 and 12 years old (n = 104) who had consulted for a malocclusion. The inclusion criteria were considered as follows: Good visibility of anatomic structures and absence of congenital craniofacial deformities. We excluded bad radiographs with errors and discrepancies: Double limits, deformities as well as children having hereditary craniofacial anomalies and underlying diseases. The cephalometric analysis was conducted according to Segner and Hassund’s method. ST’s shape was identified according to Axelsson’s classification modified by Becktor. The sample size was divided into groups: Group 1 with normal ST’s shape and Group 2 with sella’s anomaly. Statistics were performed using IBM SPSS STATISTICS 22. Data normality has been tested using Shapiro–Wilk test. The normality of variance was investigated too with Levene’s test, and comparison of means between groups was performed with t-test. Results: The prevalence of aberrations of ST’s form in Tunisian children is about 59.6%. The inclination of upper incisors to the maxilla differed in children with ST’s anomaly compared to normal kids. Children with sella aberration are characterized by retroclination of upper incisors to the maxilla. The variables which showed a statistically significant relationship between abnormalities of ST and cephalometric measurements were 1+NA with P = 0.03 and NL-NSL with P = 0.04. Conclusion: The prevalence of ST’s shape anomalies in Tunisian children is about two-thirds. It seems that the anomaly of ST influences the position of the maxilla to the cranial base and the position of upper incisors to the maxilla.

An Easy-to-Use Protocol for Segmenting and 3-D Printing Craniofacial CT-Images Using Open-Source Software

Introduction: Stereolithography, also known as 3D printing (3DP), is a versatile and useful technology with many healthcare applications. While 3DP has gained tremendous popularity, it remains a daunting and perceptibly time-consuming process for the inexperienced user, with most turning to commercially printed products. Commercial vendors are expensive. We propose that 3DP is feasible for the inexperienced user with the appropriate knowledge and tools. Methods: A 3DP protocol was created for model design and printing using open-source software and a low-cost desktop printer. It was betatested by 3 inexperienced users. The fidelity of the protocol was then tested in direct comparison to industry models made for 3 patients undergoing mandibular distraction osteogenesis, using standard cephalometric measurements. Results: All inexperienced testers were able to successfully create a 3D model using the easy-to-follow protocol without the use of any other resources. The models were created in a mean time of 170 minutes. All cephalometric measurements on the open-source printed models were equal to within 0.5 to 1.0 mm of the respective industry models. Conclusions: As the 3DP process is simplified and desktop printers and materials become more affordable, we anticipate that its implementation will become more commonplace. We describe a step-by-step, protocol using open-source software and affordable materials to create 3D models.

Standardization of Cephalograms Obtained From Various Imaging Systems

Objective To propose and validate a method for standardizing and printing cephalograms acquired from different imaging systems. Methods Validation of the proposed method was done using digital cephalograms, cone beam computed tomography (CBCT)-derived cephalograms, and direct measurements obtained from 3 dry human skulls. Each cephalogram was analyzed as-received and after standardization, using both manual and digital methods. 3-dimensional (3D) measurements were also computed from the CBCT images. After adequate blinding, 2 observers independently carried out all these measurements at 2 different times. Finally, the different cephalometric measurements of each skull were compared with the corresponding direct measurements (gold standard). Results The as-received digital cephalogram showed an inherent magnification of 33%, as determined from the calibration ruler. Compared to direct skull measurements, the as-received conventional and CBCT-derived cephalograms printed without standardization showed a reduction in measures of around 14% and 28%, respectively, whereas measurements obtained from cephalograms, which were standardized and printed by the proposed method, were comparable to direct measurements. Conclusions The findings of the validation study demonstrate the robustness of the proposed method in standardizing different cephalograms before printing.

Posterior fossa volume in idiopathic intracranial hypertension: a magnetic resonance imaging–based study

Background The etiology of idiopathic intracranial hypertension (IIH) is uncertain. Studies suggest the fundamental cause of the Chiari 1 malformation, a congenitally hypoplastic posterior fossa, may explain the genesis of IIH in some patients. Purpose To assess the hypothesis that linear and volumetric measurements of the posterior fossa (PF) can be used as predictors of IIH. Material and Methods A retrospective analysis of magnetic resonance imaging (MRI) studies on 27 patients with IIH and 14 matched controls was performed. A volumetric sagittal magnetization prepared rapid acquisition gradient echo sequence was used to derive 10 linear cephalometric measurements. Total intracranial and bony posterior fossa volumes (PFVs) were derived by manual segmentation. The ratio of PFV to total intracranial volume was calculated. Results In total, 41 participants were included, all women. Participants with IIH had higher median body mass index (BMI). No significant differences in linear cephalometric measurements, total intracranial volumes, and PFVs between the groups were identified. Linear measurements were not predictive of volumetric measurements. However, on multivariate logistic regression analysis, the likelihood of IIH decreased significantly per unit increase in relative PFV (odds ratio [OR]=3.66 × 10−50; 95% confidence interval [CI]=1.39 × 10−108 to 1.22 × 10−5; P = 0.04). Conversely, the likelihood of IIH increased per unit BMI increase (OR=1.19; 95% CI=1.04–1.47; P = 0.02). Conclusion MRI-based volumetric measurements imply that PF alterations may be partly responsible for the development of IIH and Chiari 1 malformations. Symptoms of IIH may arise due to an interplay between these and metabolic, hormonal, or other factors.

The Reliability of Two- and Three-Dimensional Cephalometric Measurements: A CBCT Study

Cephalometry is a standard diagnostic tool in orthodontic and orthognathic surgery fields. However, built-in magnification from the cephalometric machine produces double images from left- and right-side craniofacial structures on the film, which poses difficulty for accurate cephalometric tracing and measurements. The cone-beam computed tomography (CBCT) images not only allow three-dimensional (3D) analysis, but also enable the extraction of two-dimensional (2D) images without magnification. To evaluate the most reliable cephalometric analysis method, we extracted 2D lateral cephalometric images with and without magnification from twenty full-cranium CBCT datasets; images were extracted with magnification to mimic traditional lateral cephalograms. Cephalometric tracings were performed on the two types of extracted 2D lateral cephalograms and on the reconstructed 3D full cranium images by two examiners. The intra- and inter-examiner intraclass correlation coefficients (ICC) were compared between linear and angular parameters, as well as between CBCT datasets of adults and children. Our results showed that overall, tracing on 2D cephalometric images without magnification increased intra- and inter-examiner reliability, while 3D tracing reduced inter-examiner reliability. Angular parameters and children’s images had the lowest inter- and intra-examiner ICCs compared with adult samples and linear parameters. In summary, using lateral cephalograms extracted from CBCT without magnification for tracing/analysis increased reliability. Special attention is needed when analyzing young patients’ images and measuring angular parameters.

Three-Dimensional Cephalometric Landmarking and Frankfort Horizontal Plane Construction: Reproducibility of Conventional and Novel Landmarks

In some dentofacial deformity patients, especially patients undergoing surgical orthodontic treatments, Computed Tomography (CT) scans are useful to assess complex asymmetry or to plan orthognathic surgery. This assessment would be made easier for orthodontists and surgeons with a three-dimensional (3D) cephalometric analysis, which would require the localization of landmarks and the construction of reference planes. The objectives of this study were to assess manual landmarking repeatability and reproducibility (R&R) of a set of 3D landmarks and to evaluate R&R of vertical cephalometric measurements using two Frankfort Horizontal (FH) planes as references for horizontal 3D imaging reorientation. Thirty-three landmarks, divided into “conventional”, “foraminal” and “dental”, were manually located twice by three experienced operators on 20 randomly-selected CT scans of orthognathic surgery patients. R&R confidence intervals (CI) of each landmark in the -x, -y and -z directions were computed according to the ISO 5725 standard. These landmarks were then used to construct 2 FH planes: a conventional FH plane (orbitale left, porion right and left) and a newly proposed FH plane (midinternal acoustic foramen, orbitale right and left). R&R of vertical cephalometric measurements were computed using these 2 FH planes as horizontal references for CT reorientation. Landmarks showing a 95% CI of repeatability and/or reproducibility > 2 mm were found exclusively in the “conventional” landmarks group. Vertical measurements showed excellent R&R (95% CI < 1 mm) with either FH plane as horizontal reference. However, the 2 FH planes were not found to be parallel (absolute angular difference of 2.41°, SD 1.27°). Overall, “dental” and “foraminal” landmarks were more reliable than the “conventional” landmarks. Despite the poor reliability of the landmarks orbitale and porion, the construction of the conventional FH plane provided a reliable horizontal reference for 3D craniofacial CT scan reorientation.

Correlation between objective evaluation and subjective evaluation of facial profile in skeletal Type II females

Objectives: The objective of this study was to find the cephalometric measurements that correlate with the visual perception. Materials and Methods: A total of 250 lateral cephalograms of patients from the year 2016 to 2018 were hand traced and analyzed. Thirty-six hard- and soft-tissue measurements were obtained from the lateral cephalometric analysis. Silhouettes obtained from cephalometric films were rated by 10 orthodontists based on their level of convexity. For each sample, the rating of visual perception was correlated with all the cephalometric (hard and soft) measurements. Results: ANB, AF-BF, L1-NB (mm), overjet, anterior maxillary alveolar height, posterior maxillary alveolar height, lower lip to E plane, and H angle were positively correlated with the visual perception. On the contrary, Pg. to N perpendicular and Pg. to NB (mm) were negatively correlated with the visual perception. However, the measurements in the vertical dimensions did not have any significant correlations with visual perception. H angle showed a higher correlation with visual perception than the nasolabial angle, facial contour angle, and lower lip to E plane. Conclusion: The agreement between objective cephalometric measurements and subjective visual perception was less than expected. In general, only 27% of the cephalometric measurements had a significant correlation with visual perception. Therefore, orthodontic treatment planning based solely on cephalometric analysis can result in unsatisfactory treatment outcomes. An inclusion of subjective measures such as visual perception in orthodontic diagnosis and treatment planning is necessary.

Effect of anterior overbite malocclusion on smile esthetics in adult patients

Objective To investigate whether overbite affects smile esthetics. Methods This study involved 106 patients with complete pretreatment records. Lateral cephalometric tracings were used to measure hard tissue variables. Frontal smile and upper occlusal photographs were used to measure nine smile esthetic variables: arc ratio, number of teeth, upper incisor exposure, upper midline, buccal corridor ratio, smile index, archform index, lower teeth exposure, and interlabial gap. The patients were classified into three groups according to their overbites (B1: 0–4 mm, B2: >4 mm, and B3: <0 mm). Analysis of variance was performed to compare 14 cephalometric measurements and the 9 smile esthetic variables. Multiple linear regression analysis was performed to determine the influencing cephalometric factors. Results Only upper incisor exposure was significantly different among the groups. In the multiple linear regression analysis, upper incisor exposure was positively associated with the distance from the upper incisor to the palatal plane in Group B2. No significant correlations were observed between cephalometric measurements and smile variables in Groups B1 and B3. Conclusions Smile variables were not significantly different among patients with various overbite malocclusions with the exception of upper incisor exposure. Overbite malocclusions do not appear to influence smile esthetics in adult patients.

Precision of orthodontic cephalometric measurements on ultra low dose-low dose CBCT reconstructed cephalograms

Objectives To analyze differences in variation of orthodontic diagnostic measurements on lateral cephalograms reconstructed from ultra low dose-low dose (ULD-LD) cone beam computed tomography (CBCT) scans (RLC) as compared to variation of measurements on standard lateral cephalograms (SLC), and to determine if it is justifiable to replace a traditional orthodontic image set for an ULD-LD CBCT with a reconstructed lateral cephalogram. Material and methods ULD-LD CBCT images and SLCs were made of forty-three dry human skulls. From the ULD-LD CBCT dataset, a lateral cephalogram was reconstructed (RLC). Cephalometric landmarks (13 skeletal and 7 dental) were identified on both SLC and RLC twice in two sessions by two calibrated observers. Thirteen cephalometric variables were calculated. Variations of measurements, expressed as standard deviations of the 4 measurements on SLC and RLC, were analyzed using a paired sample t-test. Differences in the number of observations deviating ≥ 2.0 mm or degrees from the grand mean between SLC and RLC were analyzed using a McNemar test. Results Mean SDs for 7 out of 13 variables were significantly smaller for SLCs than those for RLCs, but differences were small. For 9 out of 13 variables, there was no significant difference between SLC and RLC for the number of measurements outside the range of 2 mm or degrees. Conclusions Based on the lower radiation dose and the small differences in variation in cephalometric measurements on reconstructed LC compared to standard dose LC, ULD-LD CBCT with reconstructed LC should be considered for orthodontic diagnostic purposes. Clinical relevance ULD-LD CBCT with reconstructed LC should be considered for orthodontic purposes.

Reproducibility of three-dimensional landmarking and Frankfort horizontal plane construction: a comparison of conventional and novel landmarks in presurgical computed tomography scans

Objectives To assess manual landmarking repeatability and reproducibility (R&R) of a set of three-dimensional (3D) landmarks and to evaluate R&R of vertical cephalometric measurements using two Frankfort Horizontal (FH) planes as references for horizontal 3D imaging reorientation. Methods Thirty-three landmarks, divided into "conventional", "foraminal" and "dental", were manually located twice by 3 experienced operators on 20 computed tomography (CT) scans of orthognathic surgery patients. R&R of the landmark localization were computed according to the ISO 5725 standard. These landmarks were then used to construct 2 FH planes: a conventional FH plane (orbitale left, porion right and left) and a newly proposed FH plane (midinternal acoustic foramen, orbitale right and left). R&R of vertical cephalometric measurements were computed using these 2 FH planes as horizontal references for CT reorientation. Results Landmarks showing a 95% confidence interval (CI) of repeatability and/or reproducibility > 2mm were found exclusively in the "conventional" landmarks group. Vertical measurements showed excellent R&R (95% CI < 1mm) with either FH plane as horizontal reference. However, the 2 FH planes were not found to be parallel (absolute angular difference of 2.41°, SD 1.27°). The average time needed to landmark one CT scan was 14 ± 3 minutes. Conclusions The "dental" and "foraminal" landmarks tended to be more reliable than the "conventional" landmarks. Despite the poor overall reliability of the landmarks orbitale and porion, the construction of the conventional FH plane using 3 landmarks provided a reliable horizontal reference for 3D craniofacial CT scan reorientation.