Background
The crestal bone level and soft tissue dimension are essential for periodontal diagnosis and phenotype determination; yet, existing measurement methods have limitations. The aim of this ...clinical study was to evaluate the correlation and accuracy of ultrasound in measuring periodontal dimensions, compared to direct clinical and cone‐beam computed tomography (CBCT) methods.
Methods
A 24‐MHz ultrasound probe prototype, specifically designed for intraoral use, was employed. Periodontal soft tissue dimensions and crestal bone levels were measured at 40 teeth and 20 single missing tooth gaps from 20 patients scheduled to receive a dental implant surgery. The ultrasound images were interpreted by two calibrated examiners. Inter‐rater agreement was calculated by using inter‐rater correlation coefficient (ICC). Ultrasound readings were compared with direct clinical and CBCT readings by using ICC and Bland‐Altman analysis.
Results
The following six parameters were measured: 1) interdental papilla height (tooth), 2) mid‐facial soft tissue height (tooth), 3) mucosal thickness (tooth), 4) soft tissue height (edentulous ridge), 5) mucosal thickness (edentulous ridge), and 6) crestal bone level (tooth). Intra‐examiner calibrations were exercised to achieve an agreement of at least 0.8. ICC between the two readers ranged from 0.482 to 0.881. ICC between ultrasound and direct readings ranged from 0.667 to 0.957. The mean difference in mucosal thickness (tooth) between the ultrasound and direct readings was −0.015 mm (95% CI: −0.655 to 0.624 mm) without statistical significance. ICC between ultrasound and CBCT ranged from 0.654 to 0.849 among the measured parameters. The mean differences between ultrasound and CBCT range from −0.213 to 0.455 mm, without statistical significance.
Conclusion
Ultrasonic imaging can be valuable for accurate and real‐time periodontal diagnosis without concerns about ionizing radiation.
Background
There is no established protocol for the low doses of cone‐beam computed tomography (CBCT) acquisition and filter application on the diagnosis of condylar morphological alterations.
...Objectives
The objective of the study was to evaluate the influence of voxel size and filter application on the diagnosis of condylar morphological alterations in CBCT using an ex vivo model.
Methods
CBCT scans of 36 temporomandibular joints were acquired using OP300 Maxio with voxel sizes of 0.085, 0.125 and 0.280 mm. Three radiologists evaluated the condyles in the CBCT volumes under three filter modes: no filter, ‘1x’ sharpen filter and ‘2x’ sharpen filter. The area under the ROC curve, sensitivity and specificity were calculated by comparing the evaluators' responses with the reference standard and compared among experimental groups using analysis of variance (ANOVA) (α = 5%).
Results
The area under the ROC curve, sensitivity and specificity were not affected by voxel size and filter application (p > .05). For osteophyte and flattening, there were more true‐positive responses in smaller voxel size. For erosion, the increase of true‐ and false‐positive responses occurred with a larger voxel size. Overall, there was a tendency to decrease true positives for osteophyte and erosion and increase false positives for flattening with the ‘2x’ sharpen filter.
Conclusions
The diagnosis of condylar morphological alterations assessed in this ex vivo analysis is not influenced by the voxel size and the application of the filters. However, attention is needed with the occurrence of false‐positive diagnosis with a larger voxel size for erosion and ‘2x’ sharpen filter for flattening.
Graphical summary of the study's main results.
Aim
The aim of this cone‐beam computed tomography (CBCT)‐based study was to evaluate the outcome of nonsurgical root canal treatment (RCT) performed for the management of large cyst‐like periapical ...lesions (LCPL) and to identify the predictive factors affecting healing.
Methodology
Fifty‐four subjects (77 permanent maxillary anterior teeth) with LCPL (>10 mm) of endodontic origin were included. A single operator performed standardized multi‐visit RCT. Patients were clinically and radiographically examined at 6, 12 months, and a CBCT scan was taken at 24 months. Two independent blinded evaluators measured the pre‐ and postoperative volume of periapical lesions on CBCT scans using ITK snap software (version 3.8.0‐beta‐20181028‐win64). The outcome was assessed as a percentage change in lesion volume and dichotomized as success (resolved/reduced) or failure (unchanged/enlarged). Ten preoperative (gender; age; intraoral draining sinus, soft tissue swelling, tooth discoloration, pulp canal obliteration, open apex, root resorption, cortical bone defect and lesion volume) and four intraoperative (apical extent and density of root filling; number of treatment visits and type of root filling) predictive factors were observed. Bivariate and stepwise multivariable linear regression analysis was performed to identify independent predictors affecting treatment outcomes. The significance level was set at 5%.
Results
A recall rate of 88% was achieved. The success rate of RCT was 82.2% (8.9% resolved, 73.3% reduced). Median lesion volume reduction was 75% (IQR 61%–93%). No pre‐ or intra‐operative factors were related to treatment failure. However, presence of preoperative cortical bone defect (palatal versus no cortical defect, β = −51.5; 95% CI: −86.9 to −16, p = .006) and apical extent of obturation (long versus flush, β = −27.2; 95% CI: −53.8 to −0.6, p = .04) were negatively associated with reduction in lesion volume (%).
Conclusion
Large cyst‐like periapical lesions may be successfully managed with RCT. Preoperative cortical bone defect and apical extent of obturation may negatively influence osseous healing.
As CBCT is widely used in dental and maxillofacial imaging, it is important for users as well as referring practitioners to understand the basic concepts of this imaging modality. This review covers ...the technical aspects of each part of the CBCT imaging chain. First, an overview is given of the hardware of a CBCT device. The principles of cone beam image acquisition and image reconstruction are described. Optimization of imaging protocols in CBCT is briefly discussed. Finally, basic and advanced visualization methods are illustrated. Certain topics in these review are applicable to all types of radiographic imaging (e.g. the principle and properties of an X-ray tube), others are specific for dental CBCT imaging (e.g. advanced visualization techniques).
Objectives
The aim of this Short Communication was to present a workflow for the superimposition of intraoral scan (IOS), cone‐beam computed tomography (CBCT), and extraoral face scan (EOS) creating ...a 3D virtual dental patient.
Material and Methods
As a proof‐of‐principle, full arch IOS, preoperative CBCT, and mimic EOS were taken and superimposed to a unique 3D data pool. The connecting link between the different files was to detect existing teeth as constant landmarks in all three data sets.
Results
This novel application technique successfully demonstrated the feasibility of building a craniofacial virtual model by image fusion of IOS, CBCT, and EOS under 3D static conditions.
Conclusions
The presented application is the first approach that realized the fusion of intraoral and facial surfaces combined with skeletal anatomy imaging. This novel 3D superimposition technique allowed the simulation of treatment planning, the exploration of the patients′ expectations, and the implementation as an effective communication tool. The next step will be the development of a real‐time 4D virtual patient in motion.
Purpose
In order to attain anatomical models, surgical guides and implants for computer‐assisted surgery, accurate segmentation of bony structures in cone‐beam computed tomography (CBCT) scans is ...required. However, this image segmentation step is often impeded by metal artifacts. Therefore, this study aimed to develop a mixed‐scale dense convolutional neural network (MS‐D network) for bone segmentation in CBCT scans affected by metal artifacts.
Method
Training data were acquired from 20 dental CBCT scans affected by metal artifacts. An experienced medical engineer segmented the bony structures in all CBCT scans using global thresholding and manually removed all remaining noise and metal artifacts. The resulting gold standard segmentations were used to train an MS‐D network comprising 100 convolutional layers using far fewer trainable parameters than alternative convolutional neural network (CNN) architectures. The bone segmentation performance of the MS‐D network was evaluated using a leave‐2‐out scheme and compared with a clinical snake evolution algorithm and two state‐of‐the‐art CNN architectures (U‐Net and ResNet). All segmented CBCT scans were subsequently converted into standard tessellation language (STL) models and geometrically compared with the gold standard.
Results
CBCT scans segmented using the MS‐D network, U‐Net, ResNet and the snake evolution algorithm demonstrated mean Dice similarity coefficients of 0.87 ± 0.06, 0.87 ± 0.07, 0.86 ± 0.05, and 0.78 ± 0.07, respectively. The STL models acquired using the MS‐D network, U‐Net, ResNet and the snake evolution algorithm demonstrated mean absolute deviations of 0.44 mm ± 0.13 mm, 0.43 mm ± 0.16 mm, 0.40 mm ± 0.12 mm and 0.57 mm ± 0.22 mm, respectively. In contrast to the MS‐D network, the ResNet introduced wave‐like artifacts in the STL models, whereas the U‐Net incorrectly labeled background voxels as bone around the vertebrae in 4 of the 9 CBCT scans containing vertebrae.
Conclusion
The MS‐D network was able to accurately segment bony structures in CBCT scans affected by metal artifacts.
Objectives
Working Group 5 was assigned the task to review the current knowledge in the area of digital technologies. Focused questions on accuracy of linear measurements when using CBCT, digital vs. ...conventional implant planning, using digital vs. conventional impressions and assessing the accuracy of static computer‐aided implant surgery (s‐CAIS) and patient‐related outcome measurements when using s‐CAIS were addressed.
Materials and methods
The literature was systematically searched, and in total, 232 articles were selected and critically reviewed following PRISMA guidelines. Four systematic reviews were produced in the four subject areas and amply discussed in the group. After emendation, they were presented to the plenary where after further modification, they were accepted.
Results
Static computer‐aided surgery (s‐CAIS), in terms of pain & discomfort, economics and intraoperative complications, is beneficial compared with conventional implant surgery. When using s‐CAIS in partially edentulous cases, a higher level of accuracy can be achieved when compared to fully edentulous cases. When using an intraoral scanner in edentulous cases, the results are dependent on the protocol that has been followed. The accuracy of measurements on CBCT scans is software dependent.
Conclusions
Because the precision intraoral scans and of measurements on CBCT scans and is not high enough to allow for the required accuracy, s‐CAIS should be considered as an additional tool for comprehensive diagnosis, treatment planning, and surgical procedures. Flapless s‐CAIS can lead to implant placement outside of the zone of keratinized mucosa and thus must be executed with utmost care.
Background: The major use of cone‐beam computed tomography (CBCT) is in implant planning. Although CBCT has been shown to be a reliable tool for measurements, we were unable to find studies comparing ...the differences between images acquired using different voxel sizes for implant planning. The aims of the present in vitro study are to verify the accuracy of linear measurements and to analyze the visibility of the mandibular canal on CBCT images obtained using different voxel sizes.
Methods: Twelve dry human hemimandibles were scanned using voxel sizes of 0.2, 0.3, and 0.4 mm, and 108 transversal CBCT images were generated, on which two examiners performed 648 linear measurements and evaluated the visibility of the mandibular canal.
Results: The global mean ± SD error between measurements on images and direct measurements was 0.23 ± 0.20 mm. CBCT measurements underestimated direct measurements in 390 cases (60.2%). All measurement errors found were <1 mm. There was a statistically significant difference (P = 0.0001 and P = 0.0028) between the two examiners only when measuring the width in two posterior sites. There was a statistically significant difference (P = 0.0242) between voxel sizes only for one of the examiners, for a measurement of height. It was possible to visualize the mandibular canal in all of the 108 images evaluated.
Conclusions: Transversal CBCT images are adequate for linear measurements in the posterior region of the mandible and provide adequate visualization of the mandibular canal using voxel sizes of 0.2, 0.3, or 0.4 mm. A voxel of 0.3 mm is a good compromise between image quality and low radiation dose.
Purpose
Current clinical application of cone‐beam CT (CBCT) is limited to patient setup. Imaging artifacts and Hounsfield unit (HU) inaccuracy make the process of CBCT‐based adaptive planning ...presently impractical. In this study, we developed a deep‐learning‐based approach to improve CBCT image quality and HU accuracy for potential extended clinical use in CBCT‐guided pancreatic adaptive radiotherapy.
Methods
Thirty patients previously treated with pancreas SBRT were included. The CBCT acquired prior to the first fraction of treatment was registered to the planning CT for training and generation of synthetic CT (sCT). A self‐attention cycle generative adversarial network (cycleGAN) was used to generate CBCT‐based sCT. For the cohort of 30 patients, the CT‐based contours and treatment plans were transferred to the first fraction CBCTs and sCTs for dosimetric comparison.
Results
At the site of abdomen, mean absolute error (MAE) between CT and sCT was 56.89 ± 13.84 HU, comparing to 81.06 ± 15.86 HU between CT and the raw CBCT. No significant differences (P > 0.05) were observed in the PTV and OAR dose‐volume‐histogram (DVH) metrics between the CT‐ and sCT‐based plans, while significant differences (P < 0.05) were found between the CT‐ and the CBCT‐based plans.
Conclusions
The image similarity and dosimetric agreement between the CT and sCT‐based plans validated the dose calculation accuracy carried by sCT. The CBCT‐based sCT approach can potentially increase treatment precision and thus minimize gastrointestinal toxicity.
The current study explores whether there is a clinically relevant distinction in the measurement of marginal bone loss when comparing high-dose (HD) versus low-dose (LD) cone beam computed tomography ...(CBCT) protocols in small and large acquisition volumes. Material and Methods: CBCTs of four human cadaveric preparates were taken in HD and LD mode in two different fields of view 8 × 8 cm2 (LV) and 5 × 5 cm2 (SV). In total, 43 sites of 15 teeth were randomly chosen, and marginal bone loss was measured twice in all protocols at 43 sites of 15 teeth by one calibrated investigator. Bland-Altman plots and Lin's concordance correlation coefficient (CCC) were calculated to assess the extent of agreement of the measurements. Additionally, the rater scored the certainty in each of the measurements.
For HD-CBCT CCC of measurements obtained using SV versus LV was 0.991. CCC of measurements obtained using SV versus LV of LD-CBCT was 0.963. Both CCC values indicated excellent agreement between the two volumes in both protocols. CCC also indicated high intramodality correlation between HD-CBCT and LD-CBCT independent of the acquisition volume (0.963 - 0.992). Bland-Altman plots also indicated no substantial differences. Results of certainty scoring showed significant differences (p = 0.004 (LV), p < 0.001(SV)) between the LD and HD-CBCT.
Accuracy of measurements of bone loss shows no clinical noticeable effects depending on the CBCT volume in this ex vivo study. There appears to be no relevant advantage of SV over LV, neither in HD-CBCT nor in LD-CBCT and additionally no relevant advantage of HD versus LD in visualizing marginal bone loss.
PDF
