Objectives
To present the results of guided bone regeneration (GBR) of atrophic edentulous ridges with customized CAD/CAM titanium meshes.
Material and methods
Forty‐one patients, presenting with 53 ...atrophic sites, were enrolled between 2018 and 2019. GBR was obtained with titanium meshes filled with autogenous bone chips and bovine bone mineral (BBM). After a mean of 7 months (range: 5–12 months), meshes were removed and 106 implants placed. After a mean of 3.5 months (range: 2–5 months), implants were uncovered and prosthetic restorations started. The outcomes were vertical and horizontal bone augmentation changes, biological complications and implant survival.
Results
Out of 53 sites, 11 underwent mesh exposure: eight of them were followed by uneventful integration of the graft, while three by partial bone loss. The mean vertical and horizontal bone gain after reconstruction was 4.78 ± 1.88 mm (range 1.00–8.90 mm) and 6.35 ± 2.10 mm (range 2.14–11.48 mm), respectively. At the time of implant placement, mean changes of initial bone gain were −0.39 ± 0.64 mm (range −3.1 to + 0.80 mm) and −0.49 ± 0.83 mm (range –3.7 to +0.4 mm), in the vertical and horizontal dimensions, respectively. Reduction of bone volume was significantly higher (p < .001 for both dimensions) in the exposed sites. The mean follow‐up of implants after loading was 10.6 ± 6.5 months (range: 2–26 months). The survival rate of implants was 100%.
Conclusion
Customized titanium meshes can represent a reliable tool for GBR of severely atrophic sites, with simplification of the surgical phases.
The accuracy of virtual interocclusal records has been evaluated, but clinical studies comparing the clinical output to the virtual design are lacking.
The purpose of this clinical study was to ...evaluate the agreement between the virtual occlusal scheme designed by a computer-aided design and computer-aided manufacturing (CAD-CAM) software program and the occlusal scheme obtained clinically on the definitive prosthesis assessed with articulating paper.
The virtual occlusal scheme design of 20 single monolithic crowns and their adjacent teeth were obtained using an intraoral scanning system (IOS) in 17 participants. These registrations were compared with conventional occlusal records obtained by applying articulating paper in 2 stages: first with 200-μm blue film and the second with 12-μm metallic red articulation tape. The analysis included both the quantity and the quality of the contacts of the conventional occlusal records referred to as the standard method. For accuracy analysis, virtual record sensitivity was calculated per crown as the percentage of true positive virtual contacts of the actual contacts identified by articulating paper. Specificity was also calculated as the percentage of true negative virtual contacts of the actual sites of clearance.
The virtual record sensitivity was 98.5 (95% confidence interval 96 to 100) for the crowns and 95 (95% confidence interval 85 to 100) for the adjacent teeth. The virtual record specificity was 88.6 (95% confidence interval 82.4 to 94.8) for the crowns and 82.6 (95% confidence interval 77.5 to 87.6) for the adjacent teeth. The agreement between the clinical and virtual contact intensities on the crowns was 83 (95% confidence interval 73 to 93) and 67.3 (95% confidence interval 56 to 78.7) for the adjacent teeth. The positive predictive value was 72.83 (95% confidence interval 60 to 86). The negative predictive value was 100% (95% confidence interval 100 to 100).
The intraoral scanning system provided clinically sufficient sensitivity and specificity for identifying the occlusal surface contacts of monolithic crowns. A slight decrease was detected in the system’s sensitivity and specificity in identifying contacts on adjacent teeth and a larger decrease identifying the intensity of these contacts.
The Dentsply Sirona CAD-CAM system intraoral scanner, design software program, and milling unit provide sufficient accuracy in designing and manufacturing single monolithic crowns in terms of the designed static occlusal scheme.
Self-adhesive resin cements (SARCs) are used because of their mechanical properties, ease of cementation protocols, and lack of requirements for acid conditioning or adhesive systems. SARCs are ...generally dual-cured, photoactivated, and self-cured, with a slight increase in acidic pH, allowing self-adhesiveness and increasing resistance to hydrolysis. This systematic review assessed the adhesive strength of SARC systems luted to different substrates and computer-aided design and manufacturing (CAD/CAM) ceramic blocks. The PubMed/MedLine and Science Direct databases were searched using the Boolean formula ((dental or tooth) AND (self-adhesive) AND (luting or cement) AND CAD-CAM) NOT (endodontics or implants). Of the 199 articles obtained, 31 were selected for the quality assessment. Lava Ultimate (resin matrix filled with nanoceramic) and Vita Enamic (polymer-infiltrated ceramic) blocks were the most tested. Rely X Unicem 2 was the most tested resin cement, followed by Rely X Unicem > Ultimate > U200, and μTBS was the test most used. The meta-analysis confirmed the substrate-dependent adhesive strength of SARCs, with significant differences between them and between SARCs and conventional resin-based adhesive cement (α < 0.05). SARCs are promising. However, one must be aware of the differences in the adhesive strengths. An appropriate combination of materials must be considered to improve the durability and stability of restorations.
Purpose
Aim of this study was to evaluate the use of computer‐aided design (CAD) models for attenuation correction (AC) of hardware components in positron emission tomography/magnetic resonance ...(PET/MR) imaging.
Methods
The technical feasibility and quantitative impact of CAD‐AC compared to computer tomography (CT)‐based AC (reference) was investigated on a modular phantom consisting of 19 different material samples (plastics and metals arranged around a cylindrical emission phantom) typically used in phantoms, patient tables, and radiofrequency (RF) coils in PET/MR. The clinical applicability of the CAD‐AC method was then evaluated on a 16‐channel RF breast coil in a PET/MR patient study. The RF breast coil in this study was specifically designed PET compatible. Using this RF breast coil, the impact on clinical PET/MR breast imaging was systematically evaluated in breast phantom measurements and, furthermore, in n = 10 PET/MR patients with breast cancer. PET data were reconstructed three times: (1) no AC (NAC), (2) established CT‐AC, and (3) CAD‐AC. For both phantom measurements, a scan without attenuating hardware components (material probes or RF breast coil) was acquired serving as reference. Relative differences in PET data were calculated for all experiments.
Results
In all phantom and patient measurements, significant gains in PET signal compared to NAC data were measurable with CT and CAD‐AC. In initial phantom experiments, mean relative differences of –0.2% for CT‐AC and 0.2% for CAD‐AC were calculated compared to reference measurements without the material probes. The application to a RF breast coil depicts that CAD‐AC results in significant gains compared to NAC data (10%) and a slight underestimation in PET signal of –1.3% in comparison to the no‐coil reference measurement. In the patient study, a total of 15 congruent lesions in all 10 patients with a mean relative difference of 14% (CT and CAD‐AC) in standardized uptake value compared to NAC data could be detected.
Conclusions
To ensure best possible PET image quality and accurate PET quantification in PET/MR imaging, the AC of hardware components such as phantoms and RF coils is important. In initial phantom experiments and in clinical application to an RF breast coil, it was found that CAD‐based AC results in significant gains in PET signal compared to NAC data and provides comparably good results to the established method of CT‐based AC.
Background
Developing computer aided diagnosis (CAD) schemes of mammograms to classify between malignant and benign breast lesions has attracted a lot of research attention over the last several ...decades. However, unlike radiologists who make diagnostic decisions based on the fusion of image features extracted from multi‐view mammograms, most CAD schemes are single‐view‐based schemes, which limit CAD performance and clinical utility.
Purpose
This study aims to develop and test a novel CAD framework that optimally fuses information extracted from ipsilateral views of bilateral mammograms using both deep transfer learning (DTL) and radiomics feature extraction methods.
Methods
An image dataset containing 353 benign and 611 malignant cases is assembled. Each case contains four images: the craniocaudal (CC) and mediolateral oblique (MLO) view of the left and right breast. First, we extract four matching regions of interest (ROIs) from images that surround centers of two suspicious lesion regions seen in CC and MLO views, as well as matching ROIs in the contralateral breasts. Next, the handcrafted radiomics (HCRs) features and VGG16 model‐generated automated features are extracted from each ROI resulting in eight feature vectors. Then, after reducing feature dimensionality and quantifying the bilateral and ipsilateral asymmetry of four ROIs to yield four new feature vectors, we test four fusion methods to build three support vector machine (SVM) classifiers by an optimal fusion of asymmetrical image features extracted from four view images.
Results
Using a 10‐fold cross‐validation method, results show that a SVM classifier trained using an optimal fusion of four view images yields the highest classification performance (AUC = 0.876 ± 0.031), which significantly outperforms SVM classifiers trained using one projection view alone, AUC = 0.817 ± 0.026 and 0.792 ± 0.026 for the CC and MLO view of bilateral mammograms, respectively (p < 0.001).
Conclusions
The study demonstrates that the shift from single‐view CAD to four‐view CAD and the inclusion of both DTL and radiomics features significantly increases CAD performance in distinguishing between malignant and benign breast lesions.
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