Academic literature on the topic 'Radiographic Tomography'

Purpose: The purpose of this study was to assess the radiographic changes in periapical status and analysis of healing determined using periapical radiographs (PA) versus cone beam computed tomography (CBCT) pre-operatively and at 3-64 months following endodontic treatment. Methods: Pre/post treatment radiograph and CBCT scans of patients who had NSRCT, NSReTx, or SRCT from July 2011-December 2018 at VCU Graduate Endodontic clinic were included in this study. Volumetric and linear measurements of periapical lesions on initial and recall PA and CBCT images were performed using three calibrated examiners. Changes and differences in the estimated area from PA to CBCT were compared using the Wilcoxon signed-rank test. McNemar’s chi-squared test was used to determine agreement in the proportion of lesions that were absent (0x0) between the PA and corresponding view of CBCT. This data was used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predicative value (NPV). Results: A total of 51 patients with a median healing time of 13 months were included in the analysis. Significant healing was observed on both PA and CBCT images (p-value Conclusion: Assessment using CBCT revealed a lower healing rate for all treatment categories compared with periapical radiographs. CBCT was more likely to detect the presence of a PARL, whereas a periapical radiograph would be less sensitive to detection of a PARL. Significant healing cannot be detected at an earlier point in time with PA radiographs or CBCT.

The main goal of this PhD project was to better understand how different types of bone grafts behave in ridge preservation procedures. There is clear evidence that, after tooth removal, a healing process takes place in which the blood clot that fills the socket is gradually substituted with new bone. This process is accompanied by a reduction in height and width of the alveolar ridge. These events may result in limited bone availability, which may compromise an adequate implant placement in order to replace the missing teeth. For this reason, the insertion of different graft materials into the extraction socket has been reported. From the available evidence, it may be concluded that ridge preservation procedures do not completely prevent, but minimize loss of horizontal and vertical ridge alterations. From an histological point of view, several studies have analyzed the histological composition of previously preserved areas in order to determine the amount of vital bone formed. Since the additional benefits of different graft materials in terms of newly formed bone compared to natural healing of the extraction socket was still unknown, we conducted a systematic review in order to answer this question. Calcium sulfate, magnesium enriched hydroxyapatite (MHA) and porcine-derived bone grafts resulted in a significant greater amount of newly formed bone than natural healing sites. Studies evaluating allografts, autologous bone and bioactive glass showed no statistical significant differences between treatment groups. Due to the great variability of the included studies, no firm conclusions could be drawn. Demineralized bovine bone mineral (DBBM) and demineralized bone bovine mineral embedded in 10% collagen matrix (DBBM-C) have been widely used in regenerative therapies and particularly in ridge preservation procedures. However, the possible differences between both grafting materials had not previously been analysed. Therefore, a double blind randomized clinical trial comparing DBBM and DBBM-C in ridge preservation procedures was conducted. A reduction in height and width was observed 5 months after tooth extraction in sites preserved either with DBBM or DBBM-C, but no significant differences were encountered between treatment groups. On the other hand, the histomorphometric analysis resulted in a similar composition in terms of new bone formation, non-mineralized connective tissue and residual graft particles in both treatment groups. From the above mentioned research projects it may be concluded that there is no consensus on which graft material offers the best outcomes from an histological point of view. More specifically, the results of the randomized clinical trial suggest that there are no statistically significant differences between DBBM and DBBM-C neither in height and width reduction of the alveolar ridge nor in their histological composition after a healing period of 5 months.<br>El objetivo final de este proyecto de tesis doctoral era conocer mejor el comportamiento de distintos materiales de injerto en la técnica de preservación alveolar. Hay evidencia de que, después de la extracción dental, comienza un proceso de cicatrización durante el cual el coágulo sanguíneo es progresivamente reemplazado por hueso nuevo. Además, se produce una reducción en altura y anchura de la cresta alveolar, que puede a su vez dar lugar a una disponibilidad ósea limitada pudiendo comprometer la posterior colocación de implantes. Por este motivo, se ha propuesto la introducción de distintos materiales de injerto en el alveolo postextracción. La literatura científica sugiere que los procedimientos de preservación alveolar minimizan estas alteraciones dimensionales de la cresta en sentido horizontal y vertical . Desde un punto de vista histológico, múltiples estudios han evaluado la composición histológica de áreas donde previamente se había realizado una preservación alveolar para determinar la cantidad y calidad del hueso nuevo formado. Como el beneficio adicional a nivel histológico de la preservación alveolar con distintos materiales de injerto respecto a la cicatrización natural del alveolo postextracción no se conocía, realizamos una revisión sistemática para responder esta cuestión. El sulfato de calcio, la hidroxiapatita enriquecida con magnesio (MHA) y los xenoinjertos de origen porcino resultaron en un porcentaje de hueso nuevo formado significativamente mayor que las áreas control. Otros estudios que utilizaron autoinjertos, aloinjertos o biovidrios no observaron diferencias significativas entre grupos. Sin embargo, debido a la gran variabilidad de los estudios incluídos, no se pudieron sacar conclusiones definitivas. El injerto bovino desproteneizado (DBBM) y el injerto bovino desproteneizado en una matriz de colágeno (DBBM-C) han sido ampliamente utilizados en terapias regenerativas y, particularmente, en preservación alveolar aunque aún no se han analizado las posibles diferencias entre ambos materiales. Por eso se realizó un ensayo clínico randomizado a doble ciego comparando DBBM y DBBM-C en preservación alveolar. Cinco meses después de la extracción, se observó una reducción en anchura y altura de la cresta alveolar en ambos grupos de tratamiento, pero no se encontraron diferencias estadísticamente significativas entre ambos. Por otro lado, el análisis histomorfométrico demostró una composición histológica similar en áreas tratadas con DBBM y áreas tratadas con DBBM-C. De los estudios mencionados previamente, se puede concluir que no hay un consenso sobre qué material de injerto ofrece los mejores resultados en cuanto a composición histológica. Particularmente, los resultados del ensayo clínico randomizado sugieren que no existen diferencias estadísticamente significativas entre DBBM y DBBM-C en cuanto a cambios dimensionales ni en cuanto a composición histológica 5 meses después de realizar la preservación alveolar.

Magister Scientiae Dentium - MSc(Dent)<br>Autologous bone grafting in conjunction with dental implant therapy is a well-accepted procedure in oral and maxillofacial rehabilitation. A variety of intraoral donor sites, such as the mandibular symphysis, the mandibular ramus and the maxillary tuberosity have been used in oral and maxillofacial reconstruction. However these sites are associated with complications. In order to reduce these complications, the anterior palate has been proposed as a potential donor site. However, the scientific literature in this regard is sparse, and larger studies are required to investigate the clinical potential of this proposed site. Aim: To determine the volume and density of available bone in the anterior palate that may be used for bone harvesting using cone-beam computed tomography (CBCT) in a select South African population. Materials and methods: One hundred previously acquired CBCT scans taken at the Diagnostic and Radiology Department of Tygerberg Oral Health Centre were analyzed for the required data. These were all acquired from a single CBCT machine (Newtom VGI®, Verona, Italy). The study sample included 52 females and 48 males ranging from ages 20 years to 80 years. The CBCT scans were divided into 3 different age groups. The first age group was between the ages of 20 and 39 years, the second age group was from 40 to 59 years and the third age group was ≥ 60 years. The volume and density of the anterior palate of the different age groups were analyzed using specific criterion. CBCT specific software (Simplant Pro Crystal®) Dentsply implants, Mannheim, Germany was used to standardize the data collection. All data was stored in a Microsoft Excel spreadsheet (Microsoft Corporation, Washington, USA). Results: The mean volume of the anterior palate in this study was 2.11 ± 0.55 cm3, with a minimum volume of 1.04 cm3 and a maximum volume of 3.82 cm3. There was no significant difference in the volume and density of the anterior palate between different age groups and no significant difference in the volume between males and females (p value = 0.227). Conclusions: The anterior palate affords a considerable amount of bone volume which is similar or even more than other intraoral donor sites. The anterior palate is a potential donor site for bone harvesting and CBCT may be regarded as an ideal tool to analyze the amount of bone available for harvesting.

Despite affecting many organ systems, the leading cause of morbidity and mortality in the cystic fibrosis (CF) population is lung disease. For the current studies we investigated elements of CF lung disease in a porcine model of CF and in people with CF. Our primary analysis tool was chest computed tomography (CT). To investigate early CF lung disease we examined three week old CF and non-CF pigs. We found three week old CF pigs to have large, irregular tracheal smooth muscle bundles, airways of reduced size, airways of irregular shape, and airways of abnormal distensibility. Three week old CF pig lung parenchyma was more heterogenous in density than three week non-CF pigs, especially in the right cephalad lung. The degree of lung tissue heterogeneity in CF pigs correlated with the degree of lung infection. Three week old CF pigs also had significantly more air trapping upon exhalation, evidence of airflow obstruction, than non-CF pigs. The degree of air trapping correlated with the degree of mucus accumulation in the airways. These data show that CF pigs spontaneously develop hallmark features of CF lung disease within weeks of birth, and that abnormal airway growth and development in CF may contribute to lung disease. This study helped set the foundation for future comparative studies involving CF therapeutics, for example, antibiotics and mucolytics. In adults with CF we performed a before drug, after drug study. The drug was ivacaftor, and it restores the basic underlying defect in a subset of people with CF: impaired function of a particular anion channel. We hypothesized that abnormal airway smooth muscle behavior in people with CF, known as “CF asthma,” is, in part, a primary pathogenic mechanism of CF lung disease. We tested our hypothesis by assaying smooth muscle tone before and after administration of ivacaftor. We limited the time duration to two days. We reasoned two days was long enough for ivacaftor to become effective, but not long enough to reverse long standing lung infection and inflammation which could affect smooth muscle function independently. The implication being, that observed changes would be directly due to restoration of the CF defect. We found evidence suggesting relaxation of airway and vascular smooth muscle tone. And, the change in airway smooth muscle tone correlated with the change in vascular smooth muscle tone. These data suggest that impaired smooth muscle function is a primary element of CF lung disease. Many of the people in our two day ivacaftor study returned for follow up after one year of ivacaftor therapy. We hypothesized that radiographic features of lung disease would improve following one year of ivacaftor therapy. We observed no change in lung volume upon inspiration, but a reduction in expiratory lung volume, approximately half of which occurred within two days. Our airway measurements were confounded by errors in scan reconstruction, however, other published studies report airway wall thinning over long term ivacaftor administration. Taken together, these studies of pigs with CF and people with CF, help us understand this disease.

Orientador: Alessandra Melchert<br>Resumo: O presente estudo teve como objetivo avaliar a influência do escore corporal sobre parâmetros cardiovasculares (ecocardiográficos, eletrocardiográficos, tomográficos e radiográficos) em papagaios verdadeiros (Amazona aestiva) anestesiados e mantidos em cativeiro. Foram utilizadas 35 aves, sem distinção de sexo, agrupadas de acordo com a condição nutricional: Grupo Magro (n=11); Grupo Ideal (n=14); Grupo Obeso (n=10). Ao exame ecocardiográfico os papagaios obesos apresentaram menor o comprimento diastólico do VD em relação ao grupo magro. Os valores da fração de encurtamento (FE) do eixo transverso do ventrículo esquerdo (VE), FE do eixo longitudinal do VE e FE do eixo longitudinal do ventrículo direito (VD), para os papagaios obesos, apesar de não significativos, foram bastante inferiores aos dos animais em escore magro e normal. Na avaliação radiográfica e tomográfica, comparando as medidas dos diferentes grupos, não foram observadas diferenças significativas. No exame eletrocardiográfico foram determinados: frequência cardíaca (FC), ritmo cardíaco, duração e amplitude da onda P, duração do intervalo PR e complexo QRS (padrão rS), duração e amplitude da onda R, duração do intervalo RR e intervalo QT e QT corrigido (QTC), duração e amplitude da onda T, não se observando diferença significativa entre os grupos estudados. Concluiu-se que, assim como em mamíferos, alterações da condição nutricional em papagaios-verdadeiros (A. aestiva) acarretam em disfunções cardiovasculares, d... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The aim of this study was to evaluate the influence of the body condition score (BCS) on cardiovascular parameters (echocardiographic, electrocardiographic, tomographic and radiographic) in parrots (Amazona aestiva) anesthetized and kept in captivity. Thirty-five birds were evaluated, regardless of gender, grouped according to the nutritional condition: Lean group (n = 11); Ideal group (n = 14); Obese group (n = 10). On echocardiographic examination, obese parrots presented lower diastolic length of the right ventricle (RV) than the lean group. The fractional shortening (FS) values of the left ventricle (LV) in transverse axis, LV FS and RV FS in longitudinal axis for the obese parrots, although not significant, were lower than those of the lean and normal animals. In the radiographic and tomographic evaluation, comparing the measurements of the different groups, no significant differences were observed. Cardiac frequency (HR), heart rate, duration and amplitude of the P wave, duration of the PR interval and QRS complex (rS pattern), duration and amplitude of the R wave, duration of the RR interval, QT and correct QT (QTc) intervals, duration and amplitude of the T wave were determined in the electrocardiographic exam. No significant difference was observed between the studied groups. It was concluded that, as in mammals, changes in nutritional status in parrots (A. aestiva) lead to cardiovascular dysfunctions, however, detected only on echocardiographic examination. The prop... (Complete abstract click electronic access below)<br>Doutor

Orientador: Francisco Haiter Neto<br>Tese (Doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba<br>Made available in DSpace on 2018-08-22T00:06:43Z (GMT). No. of bitstreams: 1 Vaz_SergioLinsdeAzevedo_D.pdf: 2097588 bytes, checksum: 48e378674d749eb9b8ea2a05042e21a4 (MD5) Previous issue date: 2013<br>Resumo: O presente estudo se propôs a avaliar a influência do tamanho de voxel e giro de escaneamento na detecção tomográfica de fenestração e deiscência peri-implantar, além do uso de filtros de imagem na detecção da deiscência peri-implantar. Em fragmentos de costelas bovinas, foi criado defeitos que simulariam fenestração e deiscência peri-implantar após a instalação de 100 implantes de titânio. As imagens foram adquiridas no tomógrafo computadorizado de feixe cônico i-CAT Next Generation, empregando FOV de 8 x 8 cm e três protocolos: A- voxel de 0,2 mm, giro de escaneamento de 180°; B- voxel de 0,2 mm, giro de 360°; C- voxel de 0,12 mm, giro de 360°. Cinco filtros do programa XoranCat foram testados: Angio Sharpen High 5x5, Shadow, Sharpen 3×3, Sharpen Mild e Smooth. Três cirurgiões-dentistas radiologistas identificaram a presença ou ausência dos defeitos. Curvas ROC foram criadas e os valores de área sob a curva (Az) comparados utilizando a Análise de Variância (ANOVA), com teste post hoc de Bonferroni (alfa de 5%). O teste de McNemar foi utilizado para comparar imagens (originais e com filtros) versus padrão ouro, bem como imagens originais versus imagens com filtros. Os resultados mostraram diferenças estatisticamente significantes entre os valores de Az dos protocolos B e C em relação ao protocolo A (p < 0,01) para deiscência. Houve diferenças estatisticamente significantes (p < 0,01) entre as imagens originais e o filtro Shadow em relação ao padrão ouro, bem como entre todos os filtros testados em relação às imagens originais. Concluiu-se que os tamanhos de voxel testados não influenciaram no diagnóstico de ambos os defeitos, enquanto que o giro de escaneamento completo (360°) foi melhor para deiscência. Diante da maior dificuldade no diagnóstico tomográfico de deiscência peri-implantar, o uso dos filtros de imagem testados é aconselhado, com exceção do filtro Shadow<br>Abstract: This study set out an assessment of the effects of two voxel sizes and scan modes of cone-beam computed tomography (CBCT) in periimplant fenestration and dehiscence detection. It also aimed to investigate whether CBCT filters would enhance the diagnosis of periimplant dehiscence. One hundred titanium implants were placed in bovine ribs in which periimplant fenestration and dehiscence were simulated. The images were acquired using the i-CAT Next Generation CBCT unit, with a FOV of 8 x 8 cm and the following protocols: A- 0.2 mm voxel size half-scan (180°); B- 0.2 mm voxel size full-scan (360°); and C- 0.12 mm voxel size full-scan (360°). Five filters of the XoranCat software were tested: Angio Sharpen High 5x5, Shadow, Sharpen 3×3, Sharpen Mild and Smooth. Three oral radiologists performed a dynamic evaluation of the presence/absence of the defects and ROC curves were created. The values of the area under the curve (Az) were compared with ANOVA and Bonferroni post-hoc test. The significance level was adopted at 5%. The McNemar test was applied to perform two comparisons in order to identify disagreements. All the enhanced and the original images were compared with the gold-standard and the original images were compared to the enhanced ones. The protocol A had significantly lower Az values than those obtained with the protocols B and C (p < 0.01) for dehiscence. The original images and the Shadow filter were statistically different from the gold-standard (p < 0.01). All the enhanced images also had statistically significant differences from the original images (p < 0.01). In conclusion, the voxel sizes did not influence in periimplant fenestration and dehiscence detection but the full-scan (360°) performed better than the half-scan for dehiscence. The use of enhancement CBCT filters for dehiscence detection is advised, with the exception of the Shadow filter<br>Doutorado<br>Radiologia Odontologica<br>Doutor em Radiologia Odontológica