969 resultados para CONE-BEAM COMPUTED TOMOGRAPHY


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Background: Excessive gingival display (EGD) has a negative impact on a pleasant smile. Minimally invasive therapeutic modalities have become the standard treatment in many dentistry fields. Therefore, the aim of this study is to compare the clinical outcomes of open-flap (OF) and minimally invasive flapless (FL) esthetic crown lengthening (ECL) for the treatment of EGD.Methods: A split-mouth randomized controlled trial was conducted in 28 patients presenting with EGD. Contralateral quadrants received ECL using OF or FL techniques. Clinical parameters were evaluated at baseline and 3, 6, and 12 months post-surgery. The local levels of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) were assessed by enzyme-linked immunosorbent assay at baseline and 3 months. Patients' perceptions regarding morbidity and esthetic appearance were also evaluated. Periodontal tissue dimensions were obtained by computed tomography at baseline and correlated with the changes in the gingival margin (GM).Results: Patients reported low morbidity and high satisfaction with esthetic appearance for both procedures (P > 0.05). RANKL and OPG concentrations were increased in the OF group at 3 months (P < 0.05). Probing depths were reduced for both groups at all time points, compared with baseline (P < 0.05). There were no differences between groups for GM reduction at any time point (P > 0.05).Conclusions: FL and OF surgeries produced stable and similar clinical results up to 12 months. FL ECL may be a predictable alternative approach for the treatment of EGD.

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Background: The problem of diagnosing whether a solitary pulmonary nodule is benign or malignant is even greater in developing countries due to a higher prevalence of infectious diseases. These infections generate a large number of patients who are generally asymptomatic and with a pulmonary nodule that cannot be accurately defined as having benign or malignant etiology.Purpose: To verify the percentages of benign versus malignant non-calcified nodules, the length of time after contrast agent injection is spiral computed tomography (CT) most sensitive and specific, and whether three postcontrast phases are necessary.Material and Methods: We studied 23 patients with solitary pulmonary nodules identified on chest radiographs or CT. Spiral scans were obtained with Swensen protocol, but at 3, 4, and 5 min after contrast injection onset. Nodules were classified as benign or malignant by histopathological examination or by an absence or presence of growth after 2 years of follow-up CT.Results: Of the 23 patients studied, 18 (78.2%) showed a final diagnosis of benign and five (21.7%) malignant nodules. Despite the small sample size, we obtained results similar to those of Swensen et al., with 80.0% sensitivity, 55.5% specificity, and 60.8% accuracy. Four minutes gave the greatest mean enhancement in both malignant and benign lesions.Conclusion: Small non-calcified benign nodules were much more frequent than malignant nodules. The best time for dynamic contrast-enhanced CT density analysis was 4 min postcontrast. As well as saving time and money, this simplified Swensen protocol with only precontrast and 4 min postcontrast phases also reduces patient exposure to ionizing radiation.

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Moderate and controlled loading environments support or enhance osteogenesis, and, consequently, a high degree of bone-to-implant contact can be acquired. This is because when osteoprogenitor cells are exposed to limited physical deformation, their differentiation into osteoblasts is enhanced. Then, some range of microstrain is considered advantageous for bone ingrowth and osseointegration. The primary stability has been considered one of the main clinical means of controlling micromotion between the implant and the forming interfacial tissue, which helps to establish the proper mechanical environment for osteogenesis. Based on the biological aspects of immediate loading (IL), the objective of this study is to present a clinical case of maxillary arch rehabilitation using immediate loading with implant-supported fixed restoration after bone graft. Ten dental implants were placed in the maxilla 6 months after the autogenous bone graft, removed from the mandible (bilateral oblique line and chin), followed by the installation of an immediate-load fixed cross-arch implant-supported restoration because primary stability was reached for 8 implants. In addition, instructions about masticatory function and how it is related to interfacial micromotion were addressed and emphasized to the patient. The reasons for the IL were further avoidance of an interim healing phase, a potential reduction in the number of clinical interventions for the patient, and aesthetic reasons. After monitoring the rehabilitation for 8 years, the authors can conclude that maxillary IL can be performed followed by a well-established treatment planning based on computed tomography, providing immediate esthetics and function to the patient even when autogenous bone graft was previously performed in the maxilla.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Statement of problem. In dental rehabilitations that involve implants, the number of implants is sometimes smaller than the number of lost teeth. This fact can affect the biomechanical behavior and success of the implants.Purpose. The purpose of this study was to investigate the mechanical behavior of different implant positions in the rehabilitation of the anterior maxilla.Material and methods. Three-dimensional models of the maxilla were created based on computed tomography images for 3 different anterior prosthetic rehabilitations. In group IL, the implants were placed in the lateral incisor positions with pontics in the central incisor positions; in group IC, the implants were in the central incisor positions with cantilevers in the lateral incisor positions; and, in group ILIC, one implant was in a lateral incisor position and one was in a central incisor position, with a pontic and a cantilever in the remaining positions. A 150 N load was distributed and applied at the center of the palatal surface of each tooth at a 45-degree angle to the long axis of the tooth. The resulting stress-strain distribution was analyzed for each group.Results. The lowest displacement of the prosthetic structure was observed in group IC, although the same group exhibited the largest displacement of the bone tissue. In the bone tissue, the von Mises stress was mainly observed in the cortical bone in all groups. The maximum value of the von Mises stress shown in the cortical tissue was 35 MPa in the implant that neighbors the cantilever in group ILIC. The maximum von Mises stress in the trabecular bone was 3.5 MPa.Conclusion. The prosthetic configuration of group IC limited the displacement of the prosthetic structure but led to greater displacement of the bone structure. The use of a cantilever increased the stress concentration in the implant and in the bone structure adjacent to the cantilever under the conditions studied here.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Hepatocellular carcinoma (HCC) is a primary tumor of the liver. After local therapies, the tumor evaluation is based on the mRECIST criteria, which involves the measurement of the maximum diameter of the viable lesion. This paper describes a computed methodology to measure through the contrasted area of the lesions the maximum diameter of the tumor by a computational algorithm 63 computed tomography (CT) slices from 23 patients were assessed. Non-contrasted liver and HCC typical nodules were evaluated, and a virtual phantom was developed for this purpose. Optimization of the algorithm detection and quantification was made using the virtual phantom. After that, we compared the algorithm findings of maximum diameter of the target lesions against radiologist measures. Computed results of the maximum diameter are in good agreement with the results obtained by radiologist evaluation, indicating that the algorithm was able to detect properly the tumor limits A comparison of the estimated maximum diameter by radiologist versus the algorithm revealed differences on the order of 0.25 cm for large-sized tumors (diameter > 5 cm), whereas agreement lesser than 1.0cm was found for small-sized tumors. Differences between algorithm and radiologist measures were accurate for small-sized tumors with a trend to a small increase for tumors greater than 5 cm. Therefore, traditional methods for measuring lesion diameter should be complemented with non-subjective measurement methods, which would allow a more correct evaluation of the contrast-enhanced areas of HCC according to the mRECIST criteria.

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Our main purpose in this study was to quantify biological tissue in computed tomography (CT) examinations with the aim of developing a skull and a chest patient equivalent phantom (PEP), both specific to infants, aged between 1 and 5 years old. This type of phantom is widely used in the development of optimization procedures for radiographic techniques, especially in computed radiography (CR) systems. In order to classify and quantify the biological tissue, we used a computational algorithm developed in Matlab (R). The algorithm performed a histogram of each CT slice followed by a Gaussian fitting of each tissue type. The algorithm determined the mean thickness for the biological tissues (bone, soft, fat, and lung) and also converted them into the corresponding thicknesses of the simulator material (aluminum, PMMA, and air). We retrospectively analyzed 148 CT examinations of infant patients, 56 for skull exams and 92 were for chest. The results provided sufficient data to construct a phantom to simulate the infant chest and skull in the posterior anterior or anterior posterior (PA/AP) view. Both patient equivalent phantoms developed in this study can be used to assess physical variables such as noise power spectrum (NPS) and signal to noise ratio (SNR) or perform dosimetric control specific to pediatric protocols.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Objective: To assess 3D morphological variations and local and systemic biomarker profiles in subjects with a diagnosis of temporomandibular joint osteoarthritis (TMJ OA).Design: Twenty-eight patients with long-term TMJ OA (39.9 +/- 16 years), 12 patients at initial diagnosis of OA (47.4 +/- 16.1 years), and 12 healthy controls (41.8 +/- 12.2 years) were recruited. All patients were female and had cone beam CT scans taken. TMJ arthrocentesis and venipuncture were performed on 12 OA and 12 age-matched healthy controls. Serum and synovial fluid levels of 50 biomarkers of arthritic inflammation were quantified by protein microarrays. Shape Analysis MANCOVA tested statistical correlations between biomarker levels and variations in condylar morphology.Results: Compared with healthy controls, the OA average condyle was significantly smaller in all dimensions except its anterior surface, with areas indicative of bone resorption along the articular surface, particularly in the lateral pole. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were significantly correlated with bone apposition of the condylar anterior surface. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGF beta b1, IFN gamma g, TNF alpha a, IL-1 alpha a, and IL-6 were significantly correlated with flattening of the lateral pole. Expression levels of ANG were significantly correlated with the articular morphology in healthy controls.Conclusions: Bone resorption at the articular surface, particularly at the lateral pole was statistically significant at initial diagnosis of TMJ OA. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were correlated with bone apposition. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGF beta 1, IFN gamma, TNF alpha, IL-1 alpha, and IL-6 were correlated with bone resorption. Published by Elsevier Ltd on behalf of Osteoarthritis Research Society International.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Central giant cell granuloma (CGCG) is an intraosseous lesion consisting of fibrous cellular tissue that contains multiple foci of hemorrhage, multinucleated giant cells, and occasional trabeculae of woven bone. An 8-year-old boy presented himself complaining of a painless swelling in the left maxilla that had started 1 year. Computed tomography (CT) scan confirmed a poorly defined multilocular radiolucent lesion in the left maxilla crossing the midline. The patient underwent enucleation through an intraoral approach of the lesion. The biopsy revealed multinucleated giant cells in a fibrous stroma. A CT was taken approximately 1 year postoperatively. There was no clinical or radiographic evidence of recurrence. Therefore, surgical treatment of CGCG can be performed, trying to preserve the surrounding anatomic structures, which can be maintained in case the lesion does not show an aggressive clinical behavior, avoiding large surgical defects which are undesirable in children.