Cone-beam Computed Tomography Data Research Articles

Dynamic 3D images fusion of the temporomandibular joints: A novel technique

ObjectivesTo demonstrate a procedure for fusing images from cone-beam computed tomography (CBCT), magnetic resonance imaging (MRI) and optical positioning tracking system to dynamically evaluate the relative motion of the temporomandibular joint (TMJ) for the diagnosis of temporomandibular disorders (TMD). MethodsCBCT data was collected from a patient wearing a fixation device with markers in the intercuspal position. The patient's mandibular movements were recorded using an optical positioning tracking system. The CBCT data were imported into a virtual simulation system to reproduce the mandibular movement. Five jaw positions were selected for 3D printing of the occlusal plate that the patient wore to undergo MRI. MRI scans were registered with the CBCT image for fusion and reconstruction. ResultsThe anatomical structures of the articular fossa, articular disc, and condyle were clearly displayed in the CBCT-MRI fused images. The spatial posture and relative position of the fossa-disc-condyle during mandibular movement could be reproduced dynamically using the 3D reconstruction model. ConclusionsThis method can visually display mandibular motion trajectories and the relative TMJ positions. Virtual reproduction provides a comprehensive understanding of the articular disc's morphology and position in different states from a 3D perspective. Clinical SignificanceThis method can be used in clinical studies of TMJ as an adjunct to the 3D dynamic diagnosis and assessment for complex patients with TMD and provide relevant data for doctors.

Automated analysis of three-dimensional CBCT images taken in natural head position that combines facial profile processing and multiple deep-learning models

Background and objectivesAnalyzing three-dimensional cone beam computed tomography (CBCT) images has become an indispensable procedure for diagnosis and treatment planning of orthodontic patients. Artificial intelligence, especially deep-learning techniques for analyzing image data, shows great potential for medical and dental image analysis and diagnosis. To explore the feasibility of automating measurement of 13 geometric parameters from three-dimensional cone beam computed tomography images taken in natural head position (NHP), this study proposed a smart system that combined a facial profile analysis algorithm with deep-learning models. Materials and methodsUsing multiple views extracted from the cone beam computed tomography data of 170 cases as a dataset, our proposed method automatically calculated 13 dental parameters by partitioning, detecting regions of interest, and extracting the facial profile. Subsequently, Mask-RCNN, a trained decentralized convolutional neural network was applied to detect 23 landmarks. All the techniques were integrated into a software application with a graphical user interface designed for user convenience. To demonstrate the system's ability to replace human experts, 30 CBCT data were selected for validation. Two orthodontists and one advanced general dentist located required landmarks by using a commercial dental program. The differences between manual and developed methods were calculated and reported as the errors. ResultsThe intraclass correlation coefficients (ICCs) and 95% confidence interval (95% CI) for intra-observer reliability were 0.98 (0.97–0.99) for observer 1; 0.95 (0.93–0.97) for observer 2; 0.98 (0.97–0.99) for observer 3 after measuring 13 parameters two times at two weeks interval. The combined ICC for intra-observer reliability was 0.97. The ICCs and 95% CI for inter-observer reliability were 0.94 (0.91–0.97). The mean absolute value of deviation was around 1 mm for the length parameters, and smaller than 2° for angle parameters. Furthermore, ANOVA test demonstrated the consistency between the measurements of the proposed method and those of human experts statistically (Fdis=2.68, ɑ=0.05). ConclusionsThe proposed system demonstrated the high consistency with the manual measurements of human experts and its applicability. This method aimed to help human experts save time and efforts for analyzing three-dimensional CBCT images of orthodontic patients.

Evaluation of 3D Modeling Workflows Using Dental CBCT Data for Periodontal Regenerative Treatment.

The cone beam computed tomography (CBCT) technology is nowadays widely used in the field of dentistry and its use in the treatment of periodontal diseases has already been tackled in the international literature. At the same time, advanced segmentation methods have been introduced in state-of-the-art medical imaging software and well-established automated techniques for 3D mesh cleaning are available in 3D model editing software. However, except for the application of simple thresholding approaches for the purposes of 3D modeling of the oral cavity using CBCT data for dental applications, which does not yield accurate results, the research that has been conducted using more specialized semi-automated thresholding in dental CBCT images using existing software packages is limited. This article aims to fill the gap in the state-of-the-art research concerning the usage of CBCT data for 3D modeling of the hard tissues of the oral cavity of patients with periodontitis using existing software tools, for the needs of designing and printing 3D scaffolds for periodontal regeneration. In this context, segmentation and 3D modeling workflows using dental CBCT data that belong to a patient with periodontitis are evaluated, comparisons between the 3D models of the teeth and the alveolar bone generated through the experiments that yielded the most satisfactory results are made, and an optimal and efficient methodology for creating 3D models of teeth and alveolar bone, especially for being used as the basis for generating bioabsorbable 3D printed scaffolds of personalized treatment against periodontitis, is discussed.

Reliability and accuracy of dental MRI for measuring root canal length of incisors and canines: a clinical pilot study

To evaluate whether high-resolution, non-contrast-enhanced dental MRI (dMRI) can reliably and accurately measure the canal length of incisors and canines compared with cone-beam computed tomography (CBCT). Three-Tesla dMRI was performed in 31 participants (mean age: 50.1 ± 14.2 years) with CBCT data. In total, 67 teeth were included (28 from the upper jaw and 39 from the lower jaw; 25 central incisors, 22 lateral incisors, and 20 canines). CBCT and dMRI datasets were reconstructed to visualize the root canal pathway in a single slice in the vestibulo-oral (V-O) and mesio-distal (M-D) direction. Root canal length was measured twice by two radiologists using dMRI and CBCT. Data were statistically analyzed by calculating intraclass correlation coefficients (ICCs) and performing Bland–Altman analysis. The reliability of dMRI measurements was excellent and comparable to that of CBCT measurements (intra-rater I/intra-rater II/inter-rater was 0.990/0.965/0.951 for dMRI vs. 0.990/0.994/0.992 for CBCT in the M-D direction and 0.991/0.956/0.967 for dMRI vs. 0.998/0.994/0.996 for CBCT in the V-O direction). According to Bland–Altman analysis, the mean (95% confidence interval) underestimation of root canal lengths was 0.67 mm (− 1.22 to 2.57) for dMRI and 0.87 mm (− 0.29 to 2.04) for CBCT in the M-D direction/V-O direction. In 92.5% of cases, dMRI measurements of canal length had an accuracy within 0–2 mm. Visualization and measurement of canal length in vivo using dMRI is feasible. The reliability of dMRI measurements was high and comparable to that of CBCT measurements. However, the spatial and temporal resolution of dMRI is lower than that of CBCT, which means dMRI measurements are less accurate than CBCT measurements. This means dMRI is currently unsuitable for measuring canal length in clinical practice.

Three-Dimensional Evaluation of the Frontal Sinus in Koreans.

(1) Background: Among the four paranasal sinuses, the frontal sinus is in the frontal bone. Recent research trends have been focusing on identifying sex based on the frontal sinus. Thus, this study aimed to provide reference data for the frontal sinus in Korean adults by comparing their sizes using a 3D program. Moreover, this study examined the correlation between the size of the frontal sinus and the length of cranial bone. (2) Methods: Cone-beam computed tomography (CBCT) data were obtained from 60 (male 30, female 30) patients in their 20 s who visited the Department of Dankook University Hospital (DKUDH IRB 2020-01-007). The provided patient CBCT data were utilized to reconstruct the patients’ frontal sinuses and cranial bones in 3D using the Mimics (version 22.0, Materialise, Leuven, Belgium) 3D program. All measurements were analyzed using SPSS (ver. 23.0, IBM Corporation, Armonk, NY, USA). (3) Results: By comparing the frontal sinus size of Korean adults according to sex using a 3D program, this study revealed that males had larger frontal sinuses than females. (4) Conclusions: The findings of this study could help in preventing complications that occur in various clinical treatments and analyzing the growth of the frontal sinus in the future.

Tooth instance segmentation based on capturing dependencies and receptive field adjustment in cone beam computed tomography

AbstractAutomatic and accurate instance segmentation of teeth can provide important support for computer‐aided orthodontic work. Traditional methods for tooth segmentation studies often ignore the rich structural features of teeth. Capturing the complete and accurate geometry as well as morphological details of a single tooth remains a challenge for current tooth segmentation studies. In this article, a new tooth segmentation deeplearning network based on capturing dependencies and receptive field adjustment in cone beam computed tomography (CBCT) is proposed to achieve automatic and accurate instance segmentation of dental CBCT data. The method acquires coarse‐level features of tooth and accurate tooth centroids in the first stage, and acquires the instance information and spatial position localization of the tooth. The encoding process in the second stage of the network introduces a guidance module for obtaining tooth geometry information based on a 3D self‐attention mechanism to capture dependencies in CBCT. The proposed tooth feature integration module is based on multiscale fusion of dilated convolutions to capture tooth detailed information at multiple scales, and the network receptive field was adjusted. Extensive evaluation, ablation, and comparison experiments demonstrate that our method exhibits state‐of‐the‐art segmentation performance and accurate instance segmentation results, reflecting their potential applicability in clinical medicine.

Accuracy of three-dimensional printed models derived from cone-beam computed tomography.

To determine the accuracy of three-dimensional (3D) printed models fabricated from cone-beam computed tomography (CBCT) scans of human mandibular dry skulls in comparison with models derived from intraoral scanner (IOS) data. Six human mandibular dry skulls were scanned by IOS and CBCT. Digital models (DMs) constructed from the IOS and CBCT data were fabricated physically using a 3D printer. The width and thickness of individual teeth and intercanine and molar widths were measured using a digital caliper. The accuracy of the DMs was compared between IOS and CBCT. Paired t-tests were used for intergroup comparisons. All intraclass correlation coefficient values for the three measurements (mesial-distal, buccal-lingual, width) exceeded 0.9. For the mandibular teeth, there were significant discrepancies in model accuracy between the IOS (average discrepancies of 0.18 ± 0.08 mm and 0.16 ± 0.12 mm for width and thickness, respectively) and CBCT (0.28 ± 0.07 mm for width, 0.37 ± 0.2 mm for thickness; P < .01). Intercanine (P = .38) and molar widths (P = .41) showed no significant difference between groups. There was a statistically significant difference in the accuracy of DMs obtained from CBCT and IOS; however, this did not seem to result in any important clinical difference. CBCT could be routinely used as an orthodontic diagnostic tool and for appliance construction.

Cone-beam CT evaluation of the effect of indirect anchorage of mini-screw assisted clear aligner on molar distalization

Objective: To evaluate the effect of indirect anchorage with mini-screw assisted clear aligner on molar distalization. Methods: Twenty-six adult patients [12 males and 14 females, aged 19 to 31 years, mean age (26.4±4.2) years], who were treated in the Department of Orthodontics, the Affiliated Stomatological Hospital of Nanchang University between January 2018 and September 2021, were included. All the patients were treated with clear aligner and mini-screw indirect anchorage to distalize maxillary molars. In the stage of molar distalization, the mini-implants were implanted between the buccal roots of the maxillary first molar and the second premolar, and rigidly connected to the maxillary second premolar as anchorage reenforcement. Until the first molar had distally moved to the designated position, the mini-implants were transferred to the buccal area between the first and the second molars and similar device was connected to the first molar. Cone-beam CT (CBCT) images were taken before the treatment (T0), at the maxillary first molar distally moved to the designated position (T1), and at the anterior teeth alignment finished (T2). The CBCT data were imported into Mimics 20.0 software for three-dimensional reconstruction. After correcting the head position, each reference point was determined in the multi-plane reconstruction view. The bilateral porion, the right orbitale, the nasion, and the anterior nasal spine were selected as reference points to construct the three-dimensional space coordinate system. The positions of the first molar, the second premolar, and the incisor were analyzed three-dimensionally. The three-dimensional position changes of maxillary first molars and maxillary second premolars during the stages of T0-T1, T1-T2, T0-T2, and the mesiodistal and vertical position changes of maxillary central incisors were analyzed. The statistical analysis was carried out using a one-way repeated measures ANOVA. Results: There was a significant difference in the sagittal position changes of the root and cusp of the maxillary central incisors among three time points (F=24.84, P<0.001; F=27.66, P=0.001), but no difference was observed between T0 and T1 (P>0.05). There was a significant difference in lingual retraction of the maxillary central incisor root [(2.17±0.42) mm] and cusp [(1.81±0.28) mm] between T1 and T2 (P<0.05). A significant difference was noted in the sagittal position changes of the root and crown of the maxillary second premolars among three time points (F=17.16, P=0.001; F=57.99, P<0.001). However, no statistical difference was detected between T0 and T1 (P>0.05) and the difference in maxillary second premolar distalization [root (1.95±0.42) mm, cusp (2.53±0.33) mm] was observed between T1 and T2 (P<0.05). There was a statistically significant difference in the sagittal position changes of the root and the crown of the maxillary first molar among three time points (F=9.37, P=0.002; F=140.26, P<0.001). The difference in the maxillary first molar distalization [crown (3.51±0.30) mm, root (1.98±0.25) mm] between T0 and T1 was significant (P<0.05). However, no significant difference in the sagittal position of the maxillary first molars was observed between T1 and T2 (P>0.05). There was a statistically significant difference in the vertical position of the center point of the root in maxillary first molar among three time points (F=59.06, P<0.001), while (2.28±0.24) mm of intrusion between T0 and T1 was exhibited (P<0.05). However, no significant difference was found in the vertical position of the maxillary first molars between T1 and T2 (P>0.05). There was no significant difference in other measurements among three time points (P>0.05). Conclusions: The effect of indirect anchorage with mini-screw-assisted clear aligner on molar distalization was positive.

Deep Learning–Based Prediction of the 3D Postorthodontic Facial Changes

With the increase of the adult orthodontic population, there is a need for an accurate and evidence-based prediction of the posttreatment face in 3 dimensions (3D). The objectives of this study are 1) to develop a 3D postorthodontic face prediction method based on a deep learning network using the patient-specific factors and orthodontic treatment conditions and 2) to validate the accuracy and clinical usability of the proposed method. Paired sets (n = 268) of pretreatment (T1) and posttreatment (T2) cone-beam computed tomography (CBCT) of adult patients were trained with a conditional generative adversarial network to generate 3D posttreatment facial data based on the patient’s gender, age, and the changes of upper (ΔU1) and lower incisor position (ΔL1) as input. The accuracy was calculated with prediction error and mean absolute distances between real T2 (T2) and predicted T2 (PT2) near 6 perioral landmark regions, as well as percentage of prediction error less than 2 mm using test sets (n = 44). For qualitative evaluation, an online survey was conducted with experienced orthodontists as panels (n = 56). Overall, PT2 indicated similar 3D changes to the T2 face, with the most apparent changes simulated in the perioral regions. The mean prediction error was 1.2 ± 1.01 mm with 80.8% accuracy. More than 50% of the experienced orthodontists were unable to distinguish between real and predicted images. In this study, we proposed a valid 3D postorthodontic face prediction method by applying a deep learning algorithm trained with CBCT data sets.

ON THE TRADE-OFF BETWEEN IMAGING DATA AND THE INDICATIONS OF CONE-BEAM COMPUTED TOMOGRAPHY: A RETROSPECTIVE STUDY

Objective: The European Academy of Dentomaxillofacial Radiology (EADMFR) implemented the Safety and Efficacy of a New and Emerging Dental X-ray Modality (SEDENTEXCT) Project in 2009 to determine the basic principles of cone-beam computed tomography (CBCT) use and established detailed criteria for specializations. One of these principles states that the correct selection of the field of view (FOV) is critical to lowering the effective radiation dose. This study aims to retrospectively analyze CBCT indications and FOV selections as determined by the clinicians in different departments. Materials and Methods: A total of 8,955 patients’ CBCT data acquired between 2015-2019 were retrospectively scanned. Data were collected and evaluated according to criteria such as FOV, acquisition indications, age, and gender. The chi-square test was used to study the differences between groups with regard to the evaluations among categorical variables. Results: A statistically significant difference was found when comparing FOV values with CBCT indications (p = 0.000). Images with the highest FOV value of 240 mm x 165 mm were taken primarily for orthognathic surgery planning. The smallest FOV value of 50 mm x 50 mm was seen to be preferred for apical pathologies and odontogenic cysts. Conclusion: Following the guidelines in the literature, the highest FOV is observed to have been used for cases that cover a larger area, such as is required in orthognathic surgery, while the smallest FOV is observed to be frequently used for endodontic cases performed to evaluate small structures such as root canal morphology and apical pathologies.

A cone beam computed tomography study based on three-dimensional cephalometric analysis of relationships between the lip-line and jaw deformity

ObjectiveThe aim of this study was to use the cone beam computed tomography (CBCT) to study the relationships between the lip-line and mandible deformity. DesignCBCT data of 20 patients with jaw deformity (experimental group) and 20 patients without mandible deformity (control group) were selected. Use three-dimensional cephalometry to measure the reconstructed images of CBCT data simulated by the Materialise Interactive Medical Image Control System (Mimics), mark the related points, lines and planes of the three-dimensional craniomaxillofacial structure, and measure relevant distances and angles. The T-test, Pearson correlation analysis and Linear regression were used to analyze the characteristics of the lip-line and jaw deformity. ResultsThere was a significant difference in the lip-line between mandible deformity group and control group. Significant positive correlations could been found among the lip-line cant, the occlusal plane cant, the mandibular plane cant and the degree of mandible deformity (r=0.964, 0.942, 0.611, P < 0.01). A linear relationship was found between the left lip-line cant Y and the menton deviation X [the mandible deflection to the right was defined as positive, and the left lip-line below frankfort horizontal was viewed as positive] as Y= 0.340 + 0.505X. ConclusionsThe lip-line of patients with jaw deformity was inclined, and the lip-line cant was positively correlated with the degree of mandible deformity, and there was a certain linear relationship between the two, which could provide a theoretical reference for clinicians to diagnose and treat patients with mandible deformity.

Reference-free learning-based similarity metric for motion compensation in cone-beam CT

Purpose. Patient motion artifacts present a prevalent challenge to image quality in interventional cone-beam CT (CBCT). We propose a novel reference-free similarity metric (DL-VIF) that leverages the capability of deep convolutional neural networks (CNN) to learn features associated with motion artifacts within realistic anatomical features. DL-VIF aims to address shortcomings of conventional metrics of motion-induced image quality degradation that favor characteristics associated with motion-free images, such as sharpness or piecewise constancy, but lack any awareness of the underlying anatomy, potentially promoting images depicting unrealistic image content. DL-VIF was integrated in an autofocus motion compensation framework to test its performance for motion estimation in interventional CBCT. Methods. DL-VIF is a reference-free surrogate for the previously reported visual image fidelity (VIF) metric, computed against a motion-free reference, generated using a CNN trained using simulated motion-corrupted and motion-free CBCT data. Relatively shallow (2-ResBlock) and deep (3-Resblock) CNN architectures were trained and tested to assess sensitivity to motion artifacts and generalizability to unseen anatomy and motion patterns. DL-VIF was integrated into an autofocus framework for rigid motion compensation in head/brain CBCT and assessed in simulation and cadaver studies in comparison to a conventional gradient entropy metric. Results. The 2-ResBlock architecture better reflected motion severity and extrapolated to unseen data, whereas 3-ResBlock was found more susceptible to overfitting, limiting its generalizability to unseen scenarios. DL-VIF outperformed gradient entropy in simulation studies yielding average multi-resolution structural similarity index (SSIM) improvement over uncompensated image of 0.068 and 0.034, respectively, referenced to motion-free images. DL-VIF was also more robust in motion compensation, evidenced by reduced variance in SSIM for various motion patterns (σ DL-VIF = 0.008 versus σ gradient entropy = 0.019). Similarly, in cadaver studies, DL-VIF demonstrated superior motion compensation compared to gradient entropy (an average SSIM improvement of 0.043 (5%) versus little improvement and even degradation in SSIM, respectively) and visually improved image quality even in severely motion-corrupted images.Conclusion: The studies demonstrated the feasibility of building reference-free similarity metrics for quantification of motion-induced image quality degradation and distortion of anatomical structures in CBCT. DL-VIF provides a reliable surrogate for motion severity, penalizes unrealistic distortions, and presents a valuable new objective function for autofocus motion compensation in CBCT.

Influence of Cone-beam Computed Tomography in Clinical Decision-making among Different Specialists in External Cervical Resorption Lesions: A Before-After Study

IntroductionInadequate management of external cervical resorption (ECR) lesions may impact the treatment outcome. This study aimed to ascertain the influence of cone-beam computed tomography (CBCT) in clinical decision-making choices in cases of ECR among dentistry specialists (endodontics, prosthodontics, oral surgery, periodontics orthodontics, and general dentistry). A secondary objective was to evaluate the self-reported level of difficulty in choosing a treatment plan before and after viewing the CBCT images. MethodsSixty examiners from different specialties were chosen to evaluate 12 cases of ECR lesions. Each case included clinical photographs, digital periapical radiographs, and a small-volume CBCT scan. In the first assessment, the examiners were given all the relevant information of each case, except the CBCT scan. Each examiner was asked to select 1 of the proposed treatment options and assess the difficulty of decision-making. Four weeks later, the examiners randomly reviewed the same 12 cases with additional information from the CBCT data. ResultsAfter the CBCT evaluation, the clinicians changed their treatment plan in 72.2% of the cases (P < .05). The self-reported level of difficulty in choosing a treatment changed in all groups after evaluating the CBCT scans (P < .05). After viewing the CBCT scan, the extraction option increased significantly in all groups (P < .05). ConclusionsCBCT scan had a significant impact on clinical decision-making in cases of ECR evaluated by different specialists.

Persistent pediatric obstructive sleep apnea treated with skeletally anchored transpalatal distraction

The aim of this study was to evaluate the impact of nasomaxillary expansion using skeletally anchored transpalatal distraction (TPD) in children without transverse maxillary deficiency that were previously treated by rapid palatal expansion (RPE). Twenty-nine consecutive children were treated by TPD. Twenty-five children, aged 10-16 years completed pre- and post-operative clinical evaluations, questionnaires (OSA-18), cone beam computed tomography (CBCT), and polysomnography (PSG). The pre- and post-operative CBCT data were used to reconstruct the 3-dimensional shape of the upper airway. Two measures of airflow function (pressure and velocity) were simulated by using computational fluid dynamics (CFD) at four different airway segments (nasal, nasopharyngeal, oropharyngeal and hypopharyngeal). Twenty-three patients (92%) experienced improvement based on PSG. The apnea hypopnea index (AHI) improved from 6.72 ± 4.34 to 3.59 ± 5.11 (p<0.001) events per hour. Clinical symptoms based on OSA-18 scores were improved in all patients. Twenty-five patients (100%) had successful expansion defined as separation of the midpalatal suture at least 1mm from anterior nasal spine (ANS) to posterior nasal spine (PNS). The nasal sidewall widening was 2.59 ± 1,54 mm at canine, 2.91 ± 1,23 mm at first molar and 2.30 ± 1,29 mm at PNS. The ratio of dental expansion to nasal expansion was 1.12:1 (2.90mm:2.59mm) at canine and 1.37:1 (3.98mm:2.91mm) at first molar. The nasal airflow pressure reduced by 76% (-275.73 to -67.28 Pa) and the nasal airflow velocity reduced by over 50% (18.60 to 8.56 m/s). Nasomaxillary expansion by skeletally anchored TPD improves OSA in children without transverse maxillary deficiency that were previously treated by RPE. A nearly parallel anterior-posterior opening of the mid-palatal suture achieves enlargement of the entire nasal passage with improvement of the airflow characteristics in the nasal and pharyngeal airway. The improved airflow characteristic is significantly correlated with the improved polysomnographic findings, thus demonstrating that nasomaxillary expansion in previously expanded patients is a viable treatment option.

Efficient Algebraic Image Reconstruction Technique for Computed Tomography

Industrial computed tomography (CT) has seen widespread adoption within certain areas of non-destructive testing (NDT), with many commercial systems capable of acquisition and reconstruction of cone-beam CT data. The majority of these systems utilise reconstruction algorithms based on the traditional filtered back-projection (FBP) methods, which are imperfect with respect to limited-angle cone-beam data. These techniques are also inherently restricted in the source trajectories that can be utilised due to the use of Fourier slice theorem. This restricts FBP-based techniques to a circular or helical trajectory. Iterative reconstruction algorithms provide a solution to these limitations as the volume reconstruction does not depend on the location or orientation of the source and detector, allowing the possibility of scanning trajectories that satisfy well-known CT data-sufficiency conditions. This paper proposes a method of reconstruction based on computationally efficient computer graphics algorithms with data collected from points in 3D space not restricted to a single circular trajectory, which is useful within NDT for automated robotic inspection. The algorithms developed allow for rapid processing of the algebraic reconstruction technique (ART) for use with X-ray transmission data for CT reconstruction. Experimental results are presented for reconstructions for circular trajectory and points on a sphere to demonstrate the suitability for NDT applications.

Assessment of Root Canal Anatomy of Maxillary and Mandibular Canine Teeth: a Cone-Beam Computed Tomography Study

To investigate the root canal anatomy of permanent maxillary and mandibular canines in a Turkish subpopulation using cone beam computed tomography (CBCT). Retrospective CBCT data of 300 patients admitted to our clinic between 2016 and 2018 were screened and evaluated. A total of 235 patients, 100 males and 135 females, aged 14-76 years (mean age 37.27±13.40) were included in this study. A total of 191 (44,8%) maxillary canine teeth and 235 (55,2%) mandibular canine teeth were examined. The number of roots and root canal morphology according to Vertucci’s classification, the presence of accessory canals, and the position of the apical foramen of the root were analyzed. The effect of gender and age on the incidence of root canal morphology was also investigated. The majority of the teeth had a Type I canal configuration in both maxillary canines (100%) and mandibular canines (92,8%). In the mandibular canines the other canal patterns found were Type III (6,8%), and Type II (0,4%). Apical foramen was centrally positioned in the majority of the teeth, 70,2% and 66,8% in maxillary and mandibular canines, respectively. The occurrence of two roots in mandibular canines was 3,8% and the root canal separation was found 53,8% and 46,2% in the middle and cervical third of the root, respectively. No significant statistical difference was observed effect of gender and age on the incidence of the root canal morphology and the position of the apical foramen. Due to the diverse morphology and the potential presence of a second canal for canine teeth among the Turkish subpopulation, dentists should perform endodontic treatments with greater care. CBCT is an accurate tool for the morphological assessment of the root canals.

A generalized image quality improvement strategy of cone-beam CT using multiple spectral CT labels in Pix2pix GAN

Objective. The quantitative and routine imaging capabilities of cone-beam CT (CBCT) are hindered from clinical applications due to the severe shading artifacts of scatter contamination. The scatter correction methods proposed in the literature only consider the anatomy of the scanned objects while disregarding the impact of incident x-ray energy spectra. The multiple-spectral model is in urgent need for CBCT scatter estimation. Approach. In this work, we incorporate the multiple spectral diagnostic multidetector CT labels into the pixel-to-pixel (Pix2pix) GAN to estimate accurate scatter distributions from CBCT projections acquired at various imaging volume sizes and x-ray energy spectra. The Pix2pix GAN combines the residual network as the generator and the PatchGAN as the discriminator to construct the correspondence between the scatter-contaminated projection and scatter distribution. The network architectures and loss function of Pix2pix GAN are optimized to achieve the best performance on projection-to-scatter transition. Results. The CBCT data of a head phantom and abdominal patients are applied to test the performance of the proposed method. The error of the corrected CBCT image using the proposed method is reduced from over 200 HU to be around 20 HU in both phantom and patient studies. The mean structural similarity index of the CT image is improved from 0.2 to around 0.9 after scatter correction using the proposed method compared with the MC-simulation method, which indicates a high similarity of the anatomy in the images before and after the proposed correction. The proposed method achieves higher accuracy of scatter estimation than using the Pix2pix GAN with the U-net generator. Significance. The proposed scheme is an effective solution to the multiple spectral CBCT scatter correction. The scatter-correction software using the proposed model will be available at: https://github.com/YangkangJiang/Cone-beam-CT-scatter-correction-tool.

Assessment of thickness of roof of the glenoid fossa in dentate, edentulous, and partially edentulous subjects using cone beam computed tomography (CBCT) - a retrospective study

ObjectivesStudies have inferred a direct association between Temporomandibular joint disorders (TMD) and the integrity of the structures associated with it such as the Glenoid fossa thereby necessitating the requirement to measure the thickness of this oft ignored entity. This study was carried out to assess the thickness of the glenoid fossa roof in dentulous, edentulous, and partially edentulous subjects using archival Cone beam computed tomography (CBCT) images. MethodAnalysis of CBCT data of 120 joints from 60 adult subjects without signs and symptoms of TMD was carried out. The scans were grouped based on the dental status as dentulous, edentulous, and partially edentulous and additionally into two sets as those below and above 40 years of age. The distance between the superior and inferior cortices of the glenoid fossa was measured indicating the thickness of the roof of the glenoid fossa in the coronal and sagittal planes, by three independent observers. Analysis of Variance (ANOVA) and Tukey's post hoc test were used to compare the association between the mean thickness of the glenoid fossa and the dentition status. A p ≤ 0.05 was considered to be significant. ResultsThere was no significant association between the mean thickness of the glenoid fossa and the dentition of the study participants of all three groups, when assessed by the three observers, except the mean thickness on the right side in the sagittal section as measured by one observer. A thicker fossa was observed in edentulous subjects when compared to dentulous participants, and the difference was statistically significant (p = 0.035). ConclusionThe thickness of the roof of the glenoid fossa demonstrated no association with the dental status of the study participants and no age or sex related differences were noted.

Internal carotid artery calcifications in a South African population: A CBCT imaging study

AbstractBackgroundStroke is the second leading cause of death globally and account for 25,000 deaths annually in South Africa. Both medial and intimal located intracranial internal carotid artery (iICA) calcifications are associated with stroke. Cone beam computed tomography (CBCT) is commonly used where advanced dental imaging of the skull is required and often includes areas outside of the field of interest. Modalities such as CBCT have great potential to identify and provide early detection of calcifications during imaging for dental purposes. The aim of the study was to investigate the presence, distribution and extent of iICA calcifications in a South African population using CBCT images. Retrospectively collected CBCT data sets of 582 patients were evaluated. All data sets were evaluated for the presence, location and severity of calcifications within the course of the internal carotid artery.ResultsAge was associated with a higher prevalence of internal carotid artery (ICA) calcifications, but sex was not. Individuals older than 61 years presented with a high number of calcifications. In total, the presence of calcifications was found in 199 patients (i.e. 34.19% of the patients). White South African individuals showed the highest prevalence. A higher degree of calcifications was also present within the C4, C5 and C6 ICA segments.ConclusionsDetection of calcifications along the course of the ICA was possible using CBCT images taken for dental treatment purposes. Early detection of calcifications allows for appropriated referral and assessment which will be beneficial to the patient presenting with ICA calcifications.

A Novel Approach to Repositioning and Stabilization of a Luxated Tooth With Displacement Using a 3D Printed Guide

The management of traumatic dental injury aims at functional and esthetic rehabilitation. After luxation injury, a displaced tooth must be replaced into its normal position as soon as possible. Incorrect tooth repositioning can cause discomfort to the patient and compromise the outcome. This report documents a novel digital technology–based approach for the management of teeth following luxation injury with displacement. A 25-year-old female reported 2 days after traumatic dental injury to her maxillary right central incisor tooth #8. After clinical and radiographic examination, a diagnosis of lateral luxation of tooth #8 was made. The preoperative high-resolution cone-beam computed tomography (CBCT) image data set confirmed palatal luxation of tooth #8 with fractured and displaced labial cortical plate. The CBCT data were imported into a medical image processing software program, and a segmentation tool was used to segment the fractured cortical plate, luxated tooth, and alveolar process. The socket is reconstructed by realigning fractured cortical bone over the alveolar process and repositioning the tooth in the virtual planning software. A three-dimensional (3D) guiding template was designed over the repositioned tooth and adjacent teeth and printed. This 3D printed guide was used for the repositioning of luxated tooth #8 and stabilizing it during the splinting procedure. This technique of using CBCT and 3D guide for repositioning is an objective, precise, and predictable approach. The 3D printed model of the dental arch after virtual tooth alignment can be used by the dentist to determine the exact splint length and contour before splinting.