Development of imaging selection criteria and procedures should precede cephalometric assessment with cone-beam computed tomography

The Role of Teleconsultations in Remote Oral Radiology Interpretation

Background

Teleconsultations have gained prominence as a viable method for delivering medical services remotely. In oral radiology, the ability to interpret radiographic images accurately is crucial for diagnosing and treating various dental conditions. The use of teleconsultations in this domain holds promise for extending specialized care to patients who are geographically distant from dental healthcare facilities.

Materials and Methods

A total of 50 patients' oral radiographic images were collected for analysis in this study. These images were obtained from diverse geographical locations, showcasing the applicability of teleconsultations. Two groups of dental professionals, one conducting in-person evaluations and the other performing remote interpretations through teleconsultations, participated in the study. The radiographic findings were assessed for concurrence between the two groups. Statistical analysis included the calculation of P values to determine the level of agreement between the in-person and teleconsultation interpretations.

Results

The results of this study revealed a substantial level of agreement between in-person and teleconsultation interpretations of oral radiographic images. The calculated P values indicated a statistically significant concordance between the two evaluation methods (P < .05). This suggests that teleconsultations can be a reliable approach for oral radiology interpretation, offering comparable results to traditional in-person evaluations.

Conclusion

In conclusion, teleconsultations have demonstrated their potential as an effective means of interpreting oral radiographic images remotely.

Comparative evaluation of mutagenic effects of two cone-beam computed tomography in oral mucosa cells

BACKGROUND

This pilot study aimed to evaluate the mutagenic effects in cells of the oral mucosa after exposure to two different cone beam computed tomography (CBCT).

METHODS

Eighteen adults were submitted to the different CBCT (Carestream CS8100 3D and I-CAT). The cells were collected immediately before the CBCT exposure and 10 days later, when the material was placed on a slide and stained using the Feulgen/Fast Green technique. Microscopic analysis counted micronuclei and other nuclear alterations, which are indicative of cytotoxicity such as pyknosis, karyolysis, karyorrhexis, and binucletion. 2000 cells were analyzed. The statistical analysis was performed with the Wilcoxon Signed-Rank test to compare the frequency of cellular alterations, and the Mann-Whitney U test to compare different CBCTs, both with a significance level of 5%.

RESULTS

There was no statistically significant difference in the micronucleated cell count before and after the exposition to the ionizing radiation from I-CAT (p = .298) and CS8100 3D (p = .203) A significate increase of pyknosis (p < .001), karyolysis (p < .001), karyorrhexis (p < .001), and binucletion (p < .001) were noted on I-CAT CBCT. There was no statistically significant difference in cellular alterations in CS8100 3D CBCT.

CONCLUSION

Despite the increase in micronuclei after exposure, this study indicates that there is no evidence of genotoxicity. On the other hand, the I-CAT CBCT produced cytotoxic effects.

Cone-Beam Computed Tomography: A New Tool on the Horizon for Forensic Dentistry

Teeth and bones of calvarium are important structures from a forensic point of view, as they are extremely resilient to destruction or decomposition, even under temperature variations. Radiology is inevitably an important tool in forensic investigations. Maxillofacial radiology provides a considerable amount of information for the identification of remains and evidence in case of legal matters. The advent of cone-beam computed tomography (CBCT) in the arena of maxillofacial 3D imaging has contributed immensely to forensic science such as the age estimation through teeth, analysis of bite marks, determination of race and sex, etc. The advantages of accuracy in imaging the anatomy, digitized technology favoring easier comparison of records and storage of records for a longer period, cost reduction, dose reduction, and easier portability have made it an unavoidable adjunct in forensic investigations. The aim of this paper is to review and highlight the importance of CBCT in successful forensic identification and analysis. This review is written to address the various aspects of CBCT as a recently developed technology that may be very useful in some forensic contexts, based on searches for current studies in the literature using PubMed, Scopus, Web of Science, and Google Scholar databases, to identify studies published since inception to December 2021, with no language restriction. In conclusion, CBCT is an accessible 3D imaging technology with many applications, one of them being in forensic sciences.

Artificial Intelligence Application in Assessment of Panoramic Radiographs

The aim of this study was to assess the reliability of the artificial intelligence (AI) automatic evaluation of panoramic radiographs (PRs). Thirty PRs, covering at least six teeth with the possibility of assessing the marginal and apical periodontium, were uploaded to the Diagnocat (LLC Diagnocat, Moscow, Russia) account, and the radiologic report of each was generated as the basis of automatic evaluation. The same PRs were manually evaluated by three independent evaluators with 12, 15, and 28 years of experience in dentistry, respectively. The data were collected in such a way as to allow statistical analysis with SPSS Statistics software (IBM, Armonk, NY, USA). A total of 90 reports were created for 30 PRs. The AI protocol showed very high specificity (above 0.9) in all assessments compared to ground truth except from periodontal bone loss. Statistical analysis showed a high interclass correlation coefficient (ICC > 0.75) for all interevaluator assessments, proving the good credibility of the ground truth and the reproducibility of the reports. Unacceptable reliability was obtained for caries assessment (ICC = 0.681) and periapical lesions assessment (ICC = 0.619). The tested AI system can be helpful as an initial evaluation of screening PRs, giving appropriate credibility reports and suggesting additional diagnostic methods for more accurate evaluation if needed.

Clinically applicable artificial intelligence system for dental diagnosis with CBCT

In this study, a novel AI system based on deep learning methods was evaluated to determine its real-time performance of CBCT imaging diagnosis of anatomical landmarks, pathologies, clinical effectiveness, and safety when used by dentists in a clinical setting. The system consists of 5 modules: ROI-localization-module (segmentation of teeth and jaws), tooth-localization and numeration-module, periodontitis-module, caries-localization-module, and periapical-lesion-localization-module. These modules use CNN based on state-of-the-art architectures. In total, 1346 CBCT scans were used to train the modules. After annotation and model development, the AI system was tested for diagnostic capabilities of the Diagnocat AI system. 24 dentists participated in the clinical evaluation of the system. 30 CBCT scans were examined by two groups of dentists, where one group was aided by Diagnocat and the other was unaided. The results for the overall sensitivity and specificity for aided and unaided groups were calculated as an aggregate of all conditions. The sensitivity values for aided and unaided groups were 0.8537 and 0.7672 while specificity was 0.9672 and 0.9616 respectively. There was a statistically significant difference between the groups (p = 0.032). This study showed that the proposed AI system significantly improved the diagnostic capabilities of dentists.

Effects of Exposure Parameters and Voxel Size for Cone-Beam Computed Tomography on the Image Matching Accuracy with an Optical Dental Scan Image: An In Vitro Study

This study is aimed at assessing the effects of exposure parameters and voxel size for cone-beam computed tomography (CBCT) on the image matching accuracy with an optical dental scan image. CBCT and optical scan images of a dry human mandible were obtained. Different CBCT settings were used: tube voltage, 60, 80, and 100 kVp; tube current, 6 and 8 mA; and voxel size, 100, 200, and 300 μm. Image matching between the CBCT and optical scan images was performed using implant planning software by dental professionals (n = 18). The image matching accuracy in each combination of CBCT settings was evaluated by assessing the linear discrepancy between the three-dimensionally reconstructed radiological image and the registered optical scan image using an image analysis software program. The Kruskal-Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the accuracy of image registration between the groups (α = 0.05). Overall, the image matching accuracy was not significantly different between tube voltage and current settings; however, significantly higher image registration errors were found at the combination of 100 kVp tube voltage/8 mA tube current (F = 8.44, P < 0.001). Changes in voxel sizes did not significantly interfere with the image registration results. No interaction was found among voltage, current, and voxel size in terms of image registration accuracy (F = 2.022, P = 0.091). Different exposure parameter settings in tube voltage and tube current did not significantly influence the image matching accuracy between CBCT and optical dental scan images; however, a high radiation dose could be inappropriate. The image matching accuracy was not significantly affected by changing the voxel sizes of CBCT.

Computational Fluid Dynamics Analysis of Nasal Airway Changes after Treatment with C-Expander

The use of the C-expander is an effective treatment modality for maxillary skeletal deficiencies which can cause ailments and significantly reduce life expectancy in late adolescents and young adults. However, the morphological and dynamic effects on the nasal airway have not been reported. The main goal of this study was to evaluate the nasal airway changes after the implementation of a C-expander. A sample of nine patients (8 females, 1 male, age range from 15 to 29 years) was included. The morphology parameters and nasal airway ventilation parameters of pretreatment and posttreatment were measured. All study data were normally distributed. A paired t-test was used to evaluate the changes before and after treatment. After expansion, the mean and standard deviation values of intercanine maxillary width (CMW) and intermolar maxillary width (MMW) increased from 35.75 ± 2.48 mm and 54.20 ± 3.17 mm to 37.87 ± 2.26 mm (P < 0.05) and 56.65 ± 3.10 mm (P < 0.05), respectively. The nasal cavity volume increased from 20320.00 ± 3468.25 mm³ to 23134.70 ± 3918.84 mm³ (P < 0.05). The nasal pressure drop decreased from 36.34 ± 3.99 Pa to 30.70 ± 3.17 Pa (P < 0.05), while the value of the maximum velocity decreased from 6.50 ± 0.31 m/s to 5.85 ± 0.37 m/s (P < 0.05). Nasal resistance dropped remarkably from 0.16 ± 0.14 Pa/ml/s to 0.08 ± 0.06 Pa/ml/s (P < 0.05). The use of C-expander can effectively broaden the area and volume of the nasal airway, having a positive effect in the reduction of nasal resistance and improvement of nasal airway ventilation. For patients suffering from maxillary width deficiency and respiratory disorders, a C-expander may be an alternative method to treat the disease.

Sagittal Relationship between the Maxillary Central Incisors and the Forehead in Digital Twins of Korean Adult Females

OBJECTIVE

Digital twins of adult Korean females were created as a tool to evaluate and compare the sagittal relationship between the maxillary central incisors and the forehead before and after orthodontic treatment.

METHODS

Digital twins were reconstructed for a total of 50 adult female patients using facial scans and cone-beam computed tomography (CBCT) images. The anteroposterior position of the maxillary central incisor and the forehead inclination were measured.

RESULTS

The control group presented a mean of 6.7 mm for the sagittal position and 17.5° for forehead inclination. The study group showed a mean of 9.3 mm for the sagittal position and 13.6° for forehead inclination. Most Korean females seeking orthodontic treatment had their maxillary central incisor anterior to the glabella. In contrast, fewer Korean females who completed their orthodontic treatments had their maxillary central incisor anterior to the glabella. Furthermore, patients who had completed the orthodontic treatment were more likely to have the maxillary central incisor between the forehead facial axis and glabella.

CONCLUSION

The use of digital twins for three-dimensional (3D) analysis of the profile implies a high clinical significance. In addition, as the facial profile of Koreans is different from that of Caucasians, careful consideration should be made when setting treatment goals for the anteroposterior position of the maxillary central incisors.

Cephalogram synthesis and landmark detection in dental cone-beam CT systems

Due to the lack of a standardized 3D cephalometric analysis methodology, 2D cephalograms synthesized from 3D cone-beam computed tomography (CBCT) volumes are widely used for cephalometric analysis in dental CBCT systems. However, compared with conventional X-ray film based cephalograms, such synthetic cephalograms lack image contrast and resolution, which impairs cephalometric landmark identification. In addition, the increased radiation dose applied to acquire the scan for 3D reconstruction causes potential health risks. In this work, we propose a sigmoid-based intensity transform that uses the nonlinear optical property of X-ray films to increase image contrast of synthetic cephalograms from 3D volumes. To improve image resolution, super resolution deep learning techniques are investigated. For low dose purpose, the pixel-to-pixel generative adversarial network (pix2pixGAN) is proposed for 2D cephalogram synthesis directly from two cone-beam projections. For landmark detection in the synthetic cephalograms, an efficient automatic landmark detection method using the combination of LeNet-5 and ResNet50 is proposed. Our experiments demonstrate the efficacy of pix2pixGAN in 2D cephalogram synthesis, achieving an average peak signal-to-noise ratio (PSNR) value of 33.8 with reference to the cephalograms synthesized from 3D CBCT volumes. Pix2pixGAN also achieves the best performance in super resolution, achieving an average PSNR value of 32.5 without the introduction of checkerboard or jagging artifacts. Our proposed automatic landmark detection method achieves 86.7% successful detection rate in the 2 mm clinical acceptable range on the ISBI Test1 data, which is comparable to the state-of-the-art methods. The method trained on conventional cephalograms can be directly applied to landmark detection in the synthetic cephalograms, achieving 93.0% and 80.7% successful detection rate in 4 mm precision range for synthetic cephalograms from 3D volumes and 2D projections, respectively.

Soft tissue thickness in Brazilian adults of different skeletal classes and facial types: A cone beam CT - Study

The aim in this study was to evaluate the influence of skeletal class, facial type, and sex on soft tissue thickness (STT) of the craniofacial midline in a Brazilian subpopulation. Thus, 121 cone beam computed tomography (CBCT) scans (54 males and 67 females, age 21 to 40 yrs) composed the study sample. Patients were classified according to skeletal class (class I, II, and III) and facial type (brachycephalic, mesocephalic, and dolichocephalic), and STT was measured (mm) in 10 landmarks in the craniofacial midline for each CBCT scan. Multivariate analysis of covariance evaluated facial STT with regard to multiple independent variables (sex, age - covariate, facial type, and skeletal class). TEM and rTEM assessed the intra-examiner agreement. STT was significantly greater in males than in females for all regions measured (p < 0.05), except for the pogonion-pogonion' landmark (p>0.05). In general, class III individuals had significantly thicker soft tissue in the maxilla - subspinale-subnasale', prosthion-labrale superius', and incision-stomion' regions, while class II subjects had thicker soft tissue in the infradentale-labrale inferius' mandibular landmark (p < 0.05). Regarding facial type, dolichocephalic individuals showed significantly thicker soft tissue in the supramentale-supramentale' mandibular landmark, whereas brachycephalic subjects had thicker soft tissue in maxillary regions - prosthion-labrale superius' and incision-stomion' (p < 0.05). rTEM values were below 5% for most landmarks, and all TEM values were below 1 mm. Skeletal class and facial type influence STT, showing a soft tissue compensation, with deeper soft tissue in areas with lower skeletal development, and/or where bone is positioned more posteriorly.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.

Cone-beam computed tomography imaging of dentoalveolar and mandibular fractures

Three-dimensional imaging methods have an important role in the diagnosis of dentomaxillofacial fractures that can not be seen on the plain films. Cone-beam computed tomography (CBCT) is one of the three-dimensional imaging methods and has facilitated dental professionals' access to cross-sectional imaging. CBCT units allow different technical parameters and the data acquired by CBCT, can be reformatted. Osseous structures are correctly examined with this technique but the technique is not useful for the examination of soft tissues. Therefore, the purpose of its use should be based on the expected diagnostic gain. The aim of this review is to present the use of CBCT with different multi-planar reformatted sections and three-dimensional reconstructions of dentoalveolar and mandibular fractures.

Application of cone beam computed tomography in facial soft tissue thickness measurements for craniofacial reconstruction

Context:

The paradigm shift from two- to three-dimensional imaging has marked the beginning of a new era in diagnosis. Newly developed cone-beam computed tomography (CBCT) designed specifically to visualize maxillofacial pathologies is being used in forensic investigations also. Facial reconstruction is a specialized forensic technique to identify the deceased from the unknown skull. It is dependent on population-specific facial soft tissue thicknesses.

Aims:

This study aims to propose the mean dataset of facial soft tissue thickness for South Indian population by utilizing CBCT. It also aims to evaluate the sex and racial differences in the values if any.

Settings and Design:

This descriptive study was conducted on CBCT scans of South Indians.

Materials and Methods:

Eighty CBCT scans of South Indian adults aged 18–80 years were selected. Facial soft tissue thickness measurements at 34 craniometric landmarks were carried out.

Statistical Analysis:

Descriptive statistics was done. Student's t-test estimated the differences of soft tissue thickness between the sexes; bilateral measurements and also racial differences. Tukey's honest significant difference test was used for multiple comparisons among Indian studies.

Results:

Males had thicker soft tissue than females in most of the landmarks. Differences in the bilateral soft tissue thicknesses were negligible. Indians had thicker facial tissues than the Koreans and CBCT was found efficient in measuring soft tissue thickness.

Conclusion:

The present study provides facial soft tissue thickness dataset using CBCT which will be useful in forensic facial reconstructions of South Indian population as well as in maxillofacial and plastic reconstructive surgeries.

A comparative study of the reproducibility of landmark identification on posteroanterior and anteroposterior cephalograms generated from cone-beam computed tomography scans

Objective

This in-vivo study aimed to compare landmark identification errors in anteroposterior (AP) and posteroanterior (PA) cephalograms generated from cone-beam computed tomography (CBCT) scan data in order to examine the feasibility of using AP cephalograms in clinical settings.

Methods

AP and PA cephalograms were generated from CBCT scans obtained from 25 adults. Four experienced and four inexperienced examiners were selected depending on their experience levels in analyzing frontal cephalograms. They identified six cephalometric landmarks on AP and PA cephalograms. The errors incurred in positioning the cephalometric landmarks on the AP and PA cephalograms were calculated by using the straight-line distance and the horizontal and vertical components as parameters.

Results

Comparison of the landmark identification errors in CBCT-generated frontal cephalograms revealed that landmark-dependent differences were greater than experience- or projection-dependent differences. Comparisons of landmark identification errors in the horizontal and vertical directions revealed larger errors in identification of the crista galli and anterior nasal spine in the vertical direction and the menton in the horizontal direction, in comparison with the other landmarks. Comparison of landmark identification errors between the AP and PA projections in CBCT-generated images revealed a slightly higher error rate in the AP projections, with no inter-examiner differences. Statistical testing of the differences in landmark identification errors between AP and PA cephalograms showed no statistically significant differences for all landmarks.

Conclusions

The reproducibility of CBCT-generated AP cephalograms is comparable to that of PA cephalograms; therefore, AP cephalograms can be generated reliably from CBCT scan data in clinical settings.

Cone Beam Computed Tomography in Orthodontics

Orthodontists treat malocclusions by applying three-dimensional forces. For years, the diagnosis of this three-dimensional condition and the related treatment plan has been based on two-dimensional imaging. Lateral and anteroposterior cephalometric, panoramic, and periapical radiographs are some of the two-dimensional radiographs routinely used in orthodontics. Despite being highly beneficial in evaluating skeletal and dental relations, these radiographs fail to provide sufficient two-dimensional information in certain cases. The purpose of this compilation is to review the use of cone-beam computed tomography in orthodontics.

Impact of cone-beam computed tomography scan mode on the diagnostic yield of chemically simulated external root resorption

INTRODUCTION

The aim of this in-vitro study was to evaluate the influence of cone-beam computed tomography scans on the diagnosis of chemically simulated external root resorption.

METHODS

One hundred extracted anterior teeth were selected. Subsurface demineralization was induced on a limited area of the apical third of the root of 49 teeth. Each tooth was placed in an empty socket of a partially edentulous dry mandible. Cone-beam computed tomography images were obtained according to 3 protocols: (1) half scan, 0.40-mm voxel size; (2) full scan, 0.40-mm voxel size; and (3) full scan, 0.125-mm voxel size. Three observers evaluated the images. Sensitivity, specificity, accuracy, and area under the curve were compared with the Cochran Q and Mann-Whitney U tests.

RESULTS

Protocol 3 had the highest sensitivity (81.63%), accuracy (80.67%), and area under the curve (0.807). There were statistically significant differences between protocol 3 and the other 2 protocols (P <0.001). The specificity of protocol 1 (84.97%) was greater than that of protocols 2 (69.93%) and 3 (79.74%); however, a statistically significant difference was found only between protocols 1 and 2 (P = 0.005).

CONCLUSIONS

A more dedicated, high-resolution scan should be acquired when one intends to investigate the early stage of external root resorption during orthodontic treatment. However, this does not imply that all orthodontic patients should be subjected to high-dose cone-beam computed tomography scans.

Camouflage of a high-angle skeletal Class II open-bite malocclusion in an adult after mini-implant failure during treatment

The treatment of skeletal anterior open-bite malocclusion requires complex orthodontic planning that considers its multifactorial etiology, treatment limitations, and high relapse rates. This case report illustrates a successful treatment approach for a skeletal high-angle Class II malocclusion in an adult with a severe open bite. The treatment consisted of a high-pull headgear therapy after mini-implants failure during fixed orthodontic therapy. Adequate esthetics and function were achieved. Despite its low probability, the unexpected event of mini-implant loosening during complex treatments should be considered. Therefore, classic orthodontic mechanics should be established, especially when treating patients for whom invasive procedures such as miniplates or orthognathic surgery are not available options.

Comparison between full face and hemifacial CBCT cephalograms in clinically symmetrical patients: a pilot study

INTRODUCTION:

One of the advantages of cone-beam computed tomography (CBCT) is the possibility of obtaining images of conventional lateral cephalograms derived from partial or complete reconstruction of facial images.

OBJECTIVE:

This study aimed at comparing full face, right and left hemifacial CBCT cephalograms of orthodontic patients without clinical facial asymmetry.

METHODS:

The sample comprised nine clinically symmetrical patients who had pretreament full face CBCT. The CBCTs were reconstructed so as to obtain full face, right and left hemifacial cephalograms. Two observers, at two different times, obtained linear and angular measurements for the images using Dolphin 3D software. Dependent and independent t-tests were used to assess the reproducibility of measurements. Analysis of Variance and Kruskal-Wallis tests were used to compare the variables obtained in the CBCT derived cephalometric views.

RESULTS:

There was good reproducibility for CBCT scans and no statistically significant differences between measurements of full face, right and left hemifacial CBCT scans.

CONCLUSIONS:

Cephalometric measurements in full face, right and left hemifacial CBCT scans in clinically symmetrical patients are similar.

Applications of Cone Beam Computed Tomography in Orthodontics: A Review

Cone Beam Computed Tomography (CBCT) is being extensively used in orthodontics for diagnostic and treatment planning, especially in complex clinical conditions. The objective of this study was to review the English language literature for current applications and trends of CBCT in orthodontic diagnosis and treatment. Several electronic databases were searched with the primary words: "orthodontics and radiography" and "cone beam computed tomography" or "CBCT." Abstracts that appeared to fulfill our inclusion criteria were selected, and the complete articles were obtained. Twenty-eight abstracts initially met our search criteria, and 12 were selected for the review. Ten articles were later added to the list after hand searching the references. It was concluded that there is a need for prospective randomized clinical trials to evaluate the risk/benefit ratio of CBCT, such as higher cost, greater risk for radiation dose (compared to digital panoramic and cephalograms) versus superior diagnosis and treatment outcomes.

Precision, reproducibility, and accuracy of bone crest level measurements of CBCT cross sections using different resolutions

OBJECTIVE

To evaluate the precision, reproducibility, and accuracy of alveolar crest level measurements on CBCT images obtained with different voxel sizes.

MATERIALS AND METHODS

CBCT exams were made of 12 dried human mandibles with voxel dimensions of 0.2, 0.3, and 0.4 mm. Bone crest level was measured directly on the mandibles with a digital caliper and on CBCT images. Images were measured twice by two examiners. Intra- and interexaminer precision and reproducibility were assessed using paired and t-tests, respectively. Accuracy was evaluated using t-tests.

RESULTS

Precision and reproducibility of bone crest level tomographic measurements was good for all voxel sizes evaluated. The images with 0.2-mm voxel size showed a decreased number of intraexaminer errors. A high accuracy for measurements of bone crest level was observed for all CBCT definitions, except for the mandibular incisors using the 0.4-mm voxel size.

CONCLUSIONS

Precision and reproducibility of alveolar bone level measurements were good for various voxel sizes. CBCT images demonstrated good accuracy for 0.2-mm and 0.3-mm voxel sizes. The mandibular incisor region needs better resolution than that provided by 0.4-mm voxel size for bone crest level measurements.

Björk-Jarabak cephalometric analysis on CBCT synthesized cephalograms with different dentofacial sagittal skeletal patterns

OBJECTIVE:

The objective of this study was to evaluate the Björk and Jabarak cephalometric analysis generated from cone-beam computed tomography (CBCT) synthesized lateral cephalograms in adults with different sagittal skeletal patterns.

METHODS:

The sample consisted of 46 CBCT synthesized cephalograms obtained from patients between 16 and 40 years old. A Björk and Jarabak cephalometric analysis among different sagittal skeletal classes was performed. Analysis of variance (ANOVA), multiple range test of Tukey, Kruskal-Wallis test, and independent t-test were used as appropriate.

RESULTS:

In comparison to the standard values: Skeletal Class III had increased gonial and superior gonial angles (P < 0.001). This trend was also evident when sex was considered. For Class I males, the sella angle was decreased (P = 0.041), articular angle increased (P = 0.027) and gonial angle decreased (P = 0.002); whereas for Class III males, the gonial angle was increased (P = 0.012). For Class I females, the articular angle was increased (P = 0.029) and the gonial angle decreased (P = 0.004). Björk's sum and Björk and Jabarak polygon sum showed no significant differences. The facial biotype presented in the three sagittal classes was mainly hypodivergent and neutral.

CONCLUSIONS:

In this sample, skeletal Class III malocclusion was strongly differentiated from the other sagittal classes, specifically in the mandible, as calculated through Björk and Jarabak analysis.

Cone Beam Computed Tomography in Orthodontics

The advent of three-dimensional (3D) imaging technology has caused a significant change in the diagnostic approach practiced in dentistry, and in particular, orthodontics. Although conventional imaging methods such as orthopantomography and lateral cephalometric and anteroposterior graphs provide sufficient information in mild to moderate orthodontic anomalies, 3D imaging can be a necessity in severe skeletal anomalies or tooth impactions. Computed tomography (CT) has been frequently used when detailed 3D imaging is necessary despite its relatively high cost, low vertical resolution, and high dose of radiation. In contrast to conventional CT application, the development of cone beam computed tomography (CBCT) technology has had important advantages over the conventional method, such as minimization of the radiation dose, image accuracy, rapid scan time, fewer image artifacts, chair-side image display, and real-time analysis. These advantages have provided dental practitioners the opportunity to benefit more frequently from 3D imaging by relatively diminishing radiation dose considerations, financial burden, and availability, in particular. Therefore, the aim of this review is to highlight the current understanding of CBCT practice in orthodontics and to summarize clinically relevant conditions.

Airway in Class I and Class II skeletal pattern: A computed tomography study

BACKGROUND AND OBJECTIVES

A normal airway is required for the normal growth of the craniofacial structures. The present study was designed to evaluate and compare the airway in Class I and Class II skeletal pattern and to see if there is any association between the airway and maxillomandibular relationship.

MATERIALS AND METHODS

Peripheral nervous system computed tomography scans of 30 patients were divided into two groups as Class I (ANB ≤ 4.5°), Class II (ANB ≥ 4.5°). The Dolphin three-dimensional version 11 was used to assess the airway.

STATISTICAL ANALYSIS

Correlations between the variables were tested with the Pearson correlation coefficient. Independent sample t-test was performed to compare the averages between the two groups. P < 0.05 was considered as statistically significant.

RESULTS

The ANB angle was negatively correlated with all the airway parameters. The airway area and volume was significantly reduced in Class II subjects compared to Class I.

CONCLUSION

The results suggest a strong association between the airway and skeletal pattern showing a reduced airway in Class II patients with a high ANB angle.

The use of three-dimensional cephalometric references in dentoskeletal symmetry diagnosis

OBJECTIVE:

The aim of this study is to assess dentoskeletal symmetry in cone-beam computed tomography (CBCT) scans of Brazilian individuals with Angle Class I malocclusion.

MATERIAL:

A total of 47 patients (22 females and 25 males) aged between 11 and 16 years old (14 years) seen in a private radiology service (CIRO, Goiânia, GO, Brazil) were assessed. All CBCT scans were obtained from January, 2009 to December, 2010. Cephalometric measurements were taken by multiplanar reconstruction (axial, coronal and sagittal) using Vista Dent3DPro 2.0 (Dentsply GAC, New York, USA). Minimum, maximum, mean and standard deviation values were arranged in tables, and Student t-test was used to determine statistical significance (P < 0.05).

RESULTS:

Data were homogeneous, and differences between the right and left sides were not significant.

CONCLUSIONS:

Cephalometric measurements of Brazilian individuals with Angle Class I malocclusion can be used to establish facial symmetry and three-dimensional standard references which might be useful for orthodontic and surgical planning.

Recent advances in imaging technologies in dentistry

Dentistry has witnessed tremendous advances in all its branches over the past three decades. With these advances, the need for more precise diagnostic tools, specially imaging methods, have become mandatory. From the simple intra-oral periapical X-rays, advanced imaging techniques like computed tomography, cone beam computed tomography, magnetic resonance imaging and ultrasound have also found place in modern dentistry. Changing from analogue to digital radiography has not only made the process simpler and faster but also made image storage, manipulation (brightness/contrast, image cropping, etc.) and retrieval easier. The three-dimensional imaging has made the complex cranio-facial structures more accessible for examination and early and accurate diagnosis of deep seated lesions. This paper is to review current advances in imaging technology and their uses in different disciplines of dentistry.

Deviation of landmarks in accordance with methods of establishing reference planes in three-dimensional facial CT evaluation

PURPOSE

This study aimed to investigate the deviation of landmarks from horizontal or midsagittal reference planes according to the methods of establishing reference planes.

MATERIALS AND METHODS

Computed tomography (CT) scans of 18 patients who received orthodontic and orthognathic surgical treatment were reviewed. Each CT scan was reconstructed by three methods for establishing three orthogonal reference planes (namely, the horizontal, midsagittal, and coronal reference planes). The horizontal (bilateral porions and bilateral orbitales) and midsagittal (crista galli, nasion, prechiasmatic point, opisthion, and anterior nasal spine) landmarks were identified on each CT scan. Vertical deviation of the horizontal landmarks and horizontal deviation of the midsagittal landmarks were measured.

RESULTS

The porion and orbitale, which were not involved in establishing the horizontal reference plane, were found to deviate vertically from the horizontal reference plane in the three methods. The midsagittal landmarks, which were not used for the midsagittal reference plane, deviated horizontally from the midsagittal reference plane in the three methods.

CONCLUSION

In a three-dimensional facial analysis, the vertical and horizontal deviations of the landmarks from the horizontal and midsagittal reference planes could vary depending on the methods of establishing reference planes.

Comparison of measurements of mandible growth using cone beam computed tomography and its synthesized cephalograms

BACKGROUND

The current study aimed to compare the measurements of the mandible morphology using 3D cone beam computed tomography (CBCT) images with those using 2D CBCT-synthesized cephalograms; to quantify errors in measurements based on 2D synthesized cephalograms; and to clarify the effects such errors have on the description of the mandibular growth.

METHODS

Mandibles of six miniature pigs were scanned monthly using CBCT over 12 months and the data were used to reconstruct the 3D bone models. Five anatomical landmarks were identified on each bone model, and the inter-marker distances and monthly distance changes were calculated and taken as the gold standard. Synthetic 2D cephalograms were also generated for each bone model using a digitally reconstructed radiography (DRR)-generation method. Errors in cephalogram measurements were determined as the differences between the calculated variables in cephalograms and the gold standard. The variations between cephalograms and the gold standard were also compared using paired t-tests.

RESULTS

While the inter-marker distance increases varied among the marker pairs, all marker pairs increased their inter-marker distances gradually every month, reaching 50% of the total annual increases during the fourth and fifth months, and then slowing down in the subsequent months. The 2D measurements significantly underestimated most of the inter-marker distances throughout the monitoring period, in most of the monthly inter-marker distance changes during the first four months, and in the total growth (p < 0.05).

CONCLUSIONS

Significant errors exist in the measurements using 2D synthesized cephalogram, underestimating the mandibular dimensions and their monthly changes in the early stages of growth, as well as the total annual growth. These results should be considered in dental treatment planning at the beginning of the treatment in order to control more precisely the treatment process and outcome.

Comparison of linear measurements between CBCT orthogonally synthesized cephalograms and conventional cephalograms

OBJECTIVES

The purposes of the study are to investigate the consistency of linear measurements between CBCT orthogonally synthesized cephalograms and conventional cephalograms and to evaluate the influence of different magnifications on these comparisons based on a simulation algorithm.

METHODS

Conventional cephalograms and CBCT scans were taken on 12 dry skulls with spherical metal markers. Orthogonally synthesized cephalograms were created from CBCT data. Linear parameters on both cephalograms were measured via Photoshop CS v. 5.0 (Adobe(®) Systems, San Jose, CA), named measurement group (MG). Bland-Altman analysis was utilized to assess the agreement of two imaging modalities. Reproducibility was investigated using paired t-test. By a specific mathematical programme "cepha", corresponding linear parameters [mandibular corpus length (Go-Me), mandibular ramus length (Co-Go), posterior facial height (Go-S)] on these two types of cephalograms were calculated, named simulation group (SG). Bland-Altman analysis was used to assess the agreement between MG and SG. Simulated linear measurements with varying magnifications were generated based on "cepha" as well. Bland-Altman analysis was used to assess the agreement of simulated measurements between two modalities.

RESULTS

Bland-Altman analysis suggested the agreement between measurements on conventional cephalograms and orthogonally synthesized cephalograms, with a mean bias of 0.47 mm. Comparison between MG and SG showed that the difference did not reach clinical significance. The consistency between simulated measurements of both modalities with four different magnifications was demonstrated.

CONCLUSIONS

Normative data of conventional cephalograms could be used for CBCT orthogonally synthesized cephalograms during this transitional period.

Cone beam computed tomography updated technology for endodontic diagnosis

Cone beam computed tomography has gained acceptance in the endodontic community for assistance with diagnosis, treatment, and evaluation of outcomes. This article reviews a multitude of applications, from basic principles to clinical applications, using specific cases and supporting literature to demonstrate the benefits for both the specialist and general practitioner.

Reliability of anatomic structures as landmarks in three-dimensional cephalometric analysis using CBCT

OBJECTIVE

To identify anatomic structures in three dimensions and examine their reliability to be used as landmarks in a three-dimensional coordinate cephalometric analysis, using cone-beam computerized tomography (CBCT).

MATERIALS AND METHODS

Thirty CBCT images were randomly selected for landmark location. Forty-two anatomic landmarks, which are not included in the traditional cephalometric landmarks, were chosen based on radiographic characteristics that make them pragmatic to mark in the CBCT image slices. The principal investigator marked the full set of landmarks on the software by navigating in the X, Y, and Z axes for every image three times, with each measurement trial being at least 1 week apart. One other investigator also located the landmarks once for each image for reliability purposes. Intraclass correlation coefficients (ICCs) were used to analyze the mean differences in landmark location in all axes.

RESULTS

Intra- and interexaminer reliability for x, y, and z coordinates for all landmarks had ICC greater than 0.95 with confidence interval of 0.88-0.99. Mean measurement differences found were <1.4 mm for all landmarks in all three coordinates. Mean measurement error differences obtained in the principal investigator's trials were primarily <0.5 mm.

CONCLUSION

The most reliable and reproducible landmarks tested for use in CBCT are mental foramina, infraorbital foramina, inferior hamulus, dens axis, foramina transversarium of atlas, medial and lateral condyles of the mandible, superior clinoid processes, and mid-clinoid.

Long-term evaluation of apical root resorption after orthodontic treatment using periapical radiography and cone beam computed tomography

OBJECTIVE: To evaluate the frequency of Apical Root Resorption (ARR) after orthodontic treatment at 52-288 months using periapical radiography (PR) and cone beam computed tomography (CBCT). METHODS: Radiographic images obtained from 58 patients, before (T1) and after orthodontic treatment (T2), and following 52-288 months of treatment were analyzed by three members of the Brazilian Board of Orthodontics. Apical structures were evaluated by PR images (T2 and T3), using Levander and Malmgren scores. The presence of ARR on CBCT images were detected only at T3. The Kolmogorov-Smirnov test was used for statistical analyses, and the level of significance was set at 5%. Kappa statistics determined interobserver agreement. RESULTS: The more frequent ARR were with scores 1 in T2 (51.6%) and T3 (53.1%), when evaluated by PR (p > 0.05). When compared the frequencies of ARR in T3 among PR and CBCT images, the differences were significant for maxillary and mandibular pre-molar groups, and for mandibular molar group (p > 0.05). The teeth with highest frequency of ARR presence using CBCT images were maxillary lateral incisors (94.5%) and mandibular central incisors (87.7%), while the premolars showed the lowest frequency. The CBCT images showed that the teeth involved in orthodontic treatment with extraction present higher ARR frequency (p < 0.05). CONCLUSION: PR showed more frequency of ARR in posterior teeth groups when compared with CBCT images. ARR did not change in long-term post treatment.

Evaluation of the reliability of measurements in cephalograms generated from cone beam computed tomography

OBJECTIVE: The purpose was to compare angular and linear measurements generated in digital cephalometric radiographs and cephalograms synthesized from three-dimensional images. METHODS: Twenty-six individuals (12 men and 14 women) with mean age of 26.3 years were selected. Digital cephalometric radiographs and CBCTs were taken on the same day. The images were imported and analyzed on Dolphin Imaging V.10.5 software, which synthesized cephalograms in perspective projection and magnification of 9.7%. A single observer marked the points and repeated the procedure with an interval of time of ten days to evaluate intraexaminer error. In the statistical analysis paired Student's t test was used to establish the correlation between the measurements. RESULTS: The angular measurements GoGn.SN and IMPA, which involved the Gonial point (Go) and the linear measurements that involved the lips presented significant difference (p < 0.05). The other measurements presented good correlation. CONCLUSION: The measurements in the synthesized cephalograms proved to be reliable.

Bone tissue amount related to upper incisors inclination

Objective:

To evaluate the amount of buccal and lingual supporting bone tissue of 60 upper central incisors and the relationship with their inclination.

Materials and Methods:

Thirty healthy adult patients with no previous orthodontic treatment were evaluated using cone-beam computed tomography. Cross-sectional views were analyzed to check the amount of the bone tissue on the cervical (cervical buccal thickness/CBT; lingual/CLT), middle (middle buccal thickness/MBT; lingual/MLT), and apical regions (apical buccal thickness/ABT; lingual/ALT). The Pearson correlation, linear regression, and analysis of variance tests were used (P &lt; .05).

Results:

The values of ABT of both teeth (11, right upper central incisor; 21, left upper central incisor) were significantly increased with the increase in the angle between the axis of the upper central incisor and the palatal plane (1/PP) (tooth 11 P  =  .034; tooth 21 P  =  .009), yet without a strong linear correlation. At the buccal and lingual surfaces, the mean apical supporting bone tissue was significantly greater than the other areas, and the middle region significantly greater than the cervical (P &lt; .001).

Conclusions:

For both surfaces (buccal and lingual), the amount of bone tissue in the apical region was significantly higher than the middle and cervical regions, and the middle region was significantly higher than the cervical region. In relation to the upper central incisor's inclination, the higher the 1/PP the higher was ABT. However, the coefficient values for both teeth were low.

Comparison of observer reliability of three-dimensional cephalometric landmark identification on subject images from Galileos and i-CAT cone beam CT

OBJECTIVES

Recently, there has been increasing interest in the use of cone beam CT (CBCT) for three-dimensional cephalometric analysis and craniofacial reconstruction in orthodontic and orthognathic surgical treatment planning. However, there is a need to redefine the cephalometric landmarks in three dimensional cephalometric analysis and to demonstrate the reproducibility of landmark identification on the type of CBCT machine being used.

METHODS

CBCT images of 20 subjects aged 15-25 years were selected, ten each from Galileos(®) (Sirona Dental Systems Inc., Bensheim, Germany) and Next Generation i-CAT(®) (Imaging Sciences International, Hatfield, PA). 2 observers located 18 landmarks on each subject twice using Dolphin-3D v. 11 software (Dolphin Imaging and Management Systems, Chatsworth, CA). Inter- and intraobserver reliability was assessed using Euclidean distances and linear mixed models.

RESULTS

Overall, the intra- and interobserver reliability was excellent for both machines. The landmarks Gonion, Nasion, Orbitale and Anterior Nasal Spine (ANS) showed the greatest median Euclidean distances for both intra- and interobserver measurements. There were significant observer effects in the unified models for Sella, Menton and all six dental landmarks. For Sella, the distances between the measures were significantly smaller (more closely spaced) on the i-CAT machine than on the Galileos in both intra- and interobserver measurements.

CONCLUSIONS

The intra- and interobserver reliability was excellent for both machines. Some of the landmarks were not as reproducible as others. Which machine produced the highest reliability depended on the landmark considered.

Use of Reference Ear Plug to improve accuracy of lateral cephalograms generated from cone-beam computed tomography scans

Objective

The purpose of this study was to evaluate the effectiveness of the use of Reference Ear Plug (REP) during cone-beam computed tomography (CBCT) scan for the generation of lateral cephalograms from CBCT scan data.

Methods

Two CBCT scans were obtained from 33 adults. One CBCT scan was acquired using conventional methods, and the other scan was acquired with the use of REP. Virtual lateral cephalograms created from each CBCT image were traced and compared with tracings of the real cephalograms obtained from the same subject.

Results

CBCT scan with REP resulted in a smaller discrepancy between real and virtual cephalograms. In comparing the real and virtual cephalograms, no measurements significantly differed from real cephalogram values in case of CBCT scan with REP, whereas many measurements significantly differed in the case of CBCT scan without REP.

Conclusion

Measurements from CBCT-generated cephalograms are more similar to those from real cephalograms when REP are used during CBCT scan. Thus, the use of REP is suggested during CBCT scan to generate accurate virtual cephalograms from CBCT scan data.

A preliminary study to determine the diagnostic reference level using dose-area product for limited-area cone beam CT

OBJECTIVES

The aim of this study was to measure the dose-area product (DAP) of limited-area cone beam CT (CBCT) units used by dental offices, and to evaluate the rationale of the DAP with an aid of optically stimulated luminescence (OSL) dosemeter in measuring radiation dose.

METHOD

The DAPs of 21 CBCT units used in the dental offices of Tokyo and the surrounding areas from five different manufacturers were measured using OSL nanoDot dosemeter. An assembly of OSL dosemeters with an X-ray film was exposed by CBCT units at exposure parameters commonly used in each dental office. DAP values were then calculated as expressed in mGy cm(2).

RESULTS

DAP values ranged from 126.7 mGy cm(2) to 1476.9 mGy cm(2), depending on the units used.

CONCLUSION

OSL dosemeter coupled with film can be utilized for a large-scale study to measure DAP. The DAP values for individual CBCT units depend not only on the field of view, but also on the exposure parameters adapted by the dental offices.

Comparison of conventional lateral cephalograms with corresponding CBCT radiographs

Purpose

This study was performed to assess the compatibility of cone beam computed tomography (CBCT) synthesized cephalograms with conventional cephalograms, and to find a method for obtaining normative values for three-dimensional (3D) assessments.

Materials and Methods

The sample group consisted of 10 adults with normal occlusion and well-balanced faces. They were imaged using conventional and CBCT cephalograms. The CBCT cephalograms were synthesized from the CBCT data using OnDemand 3D software. Twenty-one angular and 12 linear measurements from each imaging modality were compared and analyzed using paired-t test.

Results

The linear measurements between the two imaging modalities were not statistically different (p>0.05) except for the U1 to facial plane distance. The angular measurements between the two imaging modalities were not statistically different (p>0.05) with the exception of the gonial angle, ANB difference, and facial convexity.

Conclusion

Two-dimensional cephalometric norms could be readily used for 3D quantitative assessment, if corrected for lateral cephalogram distortion.

Validity and reproducibility of cephalometric measurements performed in full and hemifacial reconstructions derived from cone beam computed tomography

OBJECTIVE

To test the reproducibility and validity of angular measurements from virtual lateral cephalometric radiography (LCR) reconstructions (full and hemifacial on both sides) derived from cone beam computed tomography (CBCT).

MATERIALS AND METHODS

Fifty-eight CBCT and LCR images were selected. CBCT volume data were imported into Nemotec software, and virtual LCR images and tomographic slices from CBCT images were assessed. Three observers digitized landmarks used for 12 angular measurements in CBCT images from all patients at two different times. The LCR were evaluated by two examiners, and the mean of the measurements was used as the gold standard.

RESULTS

The virtual hemifacial LCR of tomographic slices on the right side showed statistically different higher measures. The same modality on both sides showed less absolute differences for most measures except FMIA and interincisal angles. All modalities had excellent reproducibility.

CONCLUSIONS

The angular measurements made on virtual LCR reconstructions derived from CBCT are reproducible and valid. Some advantage was found over virtual hemifacial LCR on both sides of the image, mainly in its handling facility.

Cone beam computed tomography and intraoral radiography for diagnosis of dental abnormalities in dogs and cats

The development of veterinary dentistry has substantially improved the ability to diagnose canine and feline dental abnormalities. Consequently, examinations previously performed only on humans are now available for small animals, thus improving the diagnostic quality. This has increased the need for technical qualification of veterinary professionals and increased technological investments. This study evaluated the use of cone beam computed tomography and intraoral radiography as complementary exams for diagnosing dental abnormalities in dogs and cats. Cone beam computed tomography was provided faster image acquisition with high image quality, was associated with low ionizing radiation levels, enabled image editing, and reduced the exam duration. Our results showed that radiography was an effective method for dental radiographic examination with low cost and fast execution times, and can be performed during surgical procedures.