3D-cinematic rendering for dental and maxillofacial imaging

Cinematic rendering to improve visualization of supplementary and ectopic teeth using CT datasets

OBJECTIVES

Ectopic, impacted, and supplementary teeth are the number one reason for cross-sectional imaging in pediatric dentistry. The accurate post-processing of acquired data sets is crucial to obtain precise, yet also intuitively understandable three-dimensional (3D) models, which facilitate clinical decision-making and improve treatment outcomes. Cinematic rendering (CR) is anovel visualization technique using physically based volume rendering to create photorealistic images from DICOM data. The aim of the present study was to tailor pre-existing CR reconstruction parameters for use in dental imaging with the example of the diagnostic 3D visualization of ectopic, impacted, and supplementary teeth.

METHODS

CR was employed for the volumetric image visualization of midface CT data sets. Predefined reconstruction parameters were specifically modified to visualize the presented dental pathologies, dentulous jaw, and isolated teeth. The 3D spatial relationship of the teeth, as well as their structural relationship with the antagonizing dentition, could immediately be investigated and highlighted by separate, interactive 3D visualization after segmentation through windowing.

RESULTS

To the best of our knowledge, CR has not been implemented for the visualization of supplementary and ectopic teeth segmented from the surrounding bone because the software has not yet provided appropriate customized reconstruction parameters for dental imaging. When employing our new, modified reconstruction parameters, its application presents a fast approach to obtain realistic visualizations of both dental and osseous structures.

CONCLUSIONS

CR enables dentists and oral surgeons to gain an improved 3D understanding of anatomical structures, allowing for more intuitive treatment planning and patient communication.

Visualization and quantification of coconut using advanced computed tomography postprocessing technology

INTRODUCTION

Computed tomography (CT) is a non-invasive examination tool that is widely used in medicine. In this study, we explored its value in visualizing and quantifying coconut.

MATERIALS AND METHODS

Twelve coconuts were scanned using CT for three months. Axial CT images of the coconuts were obtained using a dual-source CT scanner. In postprocessing process, various three-dimensional models were created by volume rendering (VR), and the plane sections of different angles were obtained through multiplanar reformation (MPR). The morphological parameters and the CT values of the exocarp, mesocarp, endocarp, embryo, bud, solid endosperm, liquid endosperm, and coconut apple were measured. The analysis of variances was used for temporal repeated measures and linear and non-linear regressions were used to analyze the relationship between the data.

RESULTS

The MPR images and VR models provide excellent visualization of the different structures of the coconut. The statistical results showed that the weight of coconut and liquid endosperm volume decreased significantly during the three months, while the CT value of coconut apple decreased slightly. We observed a complete germination of a coconut, its data showed a significant negative correlation between the CT value of the bud and the liquid endosperm volume (y = -2.6955x + 244.91; R2 = 0.9859), and a strong positive correlation between the height and CT value of the bud (y = 1.9576 ln(x) -2.1655; R2 = 0.9691).

CONCLUSION

CT technology can be used for visualization and quantitative analysis of the internal structure of the coconut, and some morphological changes and composition changes of the coconut during the germination process were observed during the three-month experiment. Therefore, CT is a potential tool for analyzing coconuts.

Metal Artifact Reduction in Dental CBCT Images Using Direct Sinogram Correction Combined with Metal Path-Length Weighting

Metal artifacts in dental computed tomography (CT) images, caused by highly X-ray absorbing objects, such as dental implants or crowns, often more severely compromise image readability than in medical CT images. Since lower tube voltages are used for dental CTs in spite of the more frequent presence of metallic objects in the patient, metal artifacts appear more severely in dental CT images, and the artifacts often persist even after metal artifact correction. The direct sinogram correction (DSC) method, which directly corrects the sinogram using the mapping function derived by minimizing the sinogram inconsistency, works well in the case of mild metal artifacts, but it often fails to correct severe metal artifacts. We propose a modified DSC method to reduce severe metal artifacts, and we have tested it on human dental images. We first segment the metallic objects in the CT image, and then we forward-project the segmented metal mask to identify the metal traces in the projection data with computing the metal path length for the rays penetrating the metal mask. In the sinogram correction with the DSC mapping function, we apply the weighting proportional to the metal path length. We have applied the proposed method to the phantom and patient images taken at the X-ray tube voltage of 90 kVp. We observed that the proposed method outperforms the original DSC method when metal artifacts were severe. However, we need further extensive studies to verify the proposed method for various CT scan conditions with many more patient images.

Bilateral supernumerary maxillary fourth and fifth molars: A clinical case report and literature review

Supernumerary teeth that are present in the molar region may be evident based on crowding and impaction, but most cases are asymptomatic and discovered as incidental findings during routine radiological examinations. This article reports the case of a 29-year-old woman who presented with a severe feeling of pressure in the region of the maxillary third molars that had been increasing in intensity for weeks. A clinical examination revealed crowding of the maxillary anterior teeth despite the completion of orthodontic treatment and an erupted third molar with localized gingivitis in the second quadrant. A radiographic examination revealed bilateral supernumerary maxillary fourth and fifth molars, so cone-beam computed tomography was performed to locate the supernumerary teeth precisely for a preoperative diagnosis and comprehensive treatment planning. This report presents the radiological and surgical case management of a rare case of bilateral supernumerary molars and reviews the literature regarding epidemiology and treatment options.

Application Value of the CT Scan 3D Reconstruction Technique in Maxillofacial Fracture Patients

Purpose The aim of the study was to explore the application value of computerized tomography (CT) scan 3D reconstruction technology in maxillofacial fracture patients. Methods A total of 80 maxillofacial fracture patients who underwent surgical treatment in Shijiazhuang People's Hospital from January 2019 to January 2020 were enrolled. All of them received 128-slice spiral CT  scans before surgery, and the images were subjected to multiplanar reconstruction (MRP) and volume reconstruction (VR). Results A total of 181 fractures were found in 80 patients with maxillofacial fractures. The detection rates of axial CT, MRP, and VR were 77.90% (141/181), 93.92% (170/181), and 97.79% (177/181), respectively. The detection rates of the four inspection methods were statistically different. Taking the findings of surgical anatomy as the gold standard, the sensitivity of MRP and VR for the diagnosis of maxillofacial fractures was 90.06% (163/170) and 95.56% (174/177), with no significant difference. Conclusion CT scan 3D reconstruction technology has a high application value in the clinical diagnosis and treatment of maxillofacial fracture patients.

Clinical application of cinematic rendering in maxillofacial fractures

The purpose of this study was to evaluate the clinical application of cinematically rendered reconstructions of maxillofacial fractures. Ten surgeons and eight radiologists were shown three-dimensional images of 25 different patient cases, generated using both the volume rendering (VR) technique and the cinematic rendering (CR) technique. They were asked to mark the site of the fracture on the three-dimensional images and record the time this activity took. The effectiveness of the reconstructions to communicate with patients was assessed through the opinions of the surgeons and radiologists, as well as 25 patients. Subjective evaluations of the clinical value of the images were performed by the 18 surgeons and radiologists using a 10-item questionnaire. The percentages of correctly identified fractures of the nasal bone (P = 0.034), fracture dislocation (P < 0.001), and free bone fragments (P < 0.001) were significantly higher for CR images when compared to VR images, and identification took an average of 20.81 seconds for CR and 27.48 seconds for VR (P < 0.001). CR images were found to be more beneficial for communication with patients and scored higher for the display of fracture dislocation and free bone fragments than VR images (P < 0.05). CR images were found to have high clinical value in the visualization of maxillofacial fractures.

Predictive factors associated with adjacent teeth root resorption of palatally impacted canines in Arabian population: a cone-beam computed tomography analysis

Background

This study aimed to evaluate three-dimensionally the factors associated with adjacent teeth root resorption of palatally impacted canines.

Methods

In this retrospective cross-sectional study, one-hundred and fourteen cone beam computed tomography scans with palatally impacted maxillary canines were evaluated for the presence of adjacent root resorption. Seven parameters were analyzed: alignment of maxillary incisors, presence of deciduous canines, first premolars’ roots configuration, impacted canines rotation, angulation of impacted canine to the midline, contact relationship, and area of contact with adjacent teeth. The association between dependent and independent qualitative and quantitative variables was analyzed using chi-square and independent student’s t-test, respectively. The multivariate analysis was performed using regression analysis. The significant value was set at P ≤ 0.05.

Results

The overall incidence of vertical, horizontal impaction and adjacent root resorption were 92, 8 and 77.2%, respectively. The apical third was the most involved area (57%); resorption of a single tooth was found in 21.9% of the total sample. The most common resorbed teeth were lateral first premolars (24.6%), followed by central lateral incisors (20.2%), and lateral incisors (15.8%) of the total sample. The severity of resorption was highest in grade I (31.5%) and lowest in grade III (7.6%). Three variables showed significant differences between resorption and non-resorption groups namely; canine rotation (P < 0.013), contact relationship (P < 0.001), and area of contact with adjacent teeth (P < 0.001). Regression analysis revealed an association between adjacent root resorption and permanent canine rotation, adjacent premolars’ roots configuration, contact relationship, and area of contact (P < 0.05).

Conclusion

Two-thirds of impacted maxillary canines showed a form of root resorption. The most commonly resorbed tooth was the lateral incisors while the least affected one was the central incisors with apical one-third being of the highest risk. The predisposing factors including the canine rotation, premolar with separated roots, contact relationship, and area of contact with adjacent teeth are to be considered for any interceptive treatment.

Cone-beam computed tomography cinematic rendering: clinical, teaching and research applications

Cone-beam computed tomography (CBCT) is an essential imaging method that increases the accuracy of diagnoses, planning and follow-up of endodontic complex cases. Image postprocessing and subsequent visualization relies on software for three-dimensional navigation, and application of indexation tools to provide clinically useful information according to a set of volumetric data. Image postprocessing has a crucial impact on diagnostic quality and various techniques have been employed on computed tomography (CT) and magnetic resonance imaging (MRI) data sets. These include: multiplanar reformations (MPR), maximum intensity projection (MIP) and volume rendering (VR). A recent advance in 3D data visualization is the new cinematic rendering reconstruction method, a technique that generates photorealistic 3D images from conventional CT and MRI data. This review discusses the importance of CBCT cinematic rendering for clinical decision-making, teaching, and research in Endodontics, and a presents series of cases that illustrate the diagnostic value of 3D cinematic rendering in clinical care.