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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Acurácia de medidas lineares em região posterior de mandíbulas obtidas por tomografia computadorizada de feixe cônico através de diferentes protocolos de aquisição / Accuracy of linear measurements in posterior region of mandible obtained by cone beam computed tomography through different acquisition protocols

Renata de Saldanha da Gama 05 August 2013 (has links)
A utilização da tomografia computadorizada de feixe cônico (TCFC) permite avaliar a altura e espessura do osso remanescente para a instalação de implantes. As mandíbulas atrésicas necessitam de maior grau de detalhamento para obtenção de medidas. A autora, no presente estudo, avaliou a influência do tamanho dos voxels (0,125mm e 0,25mm) nas medidas de altura e espessura em 10 mandíbulas desdentadas e atrésicas. Para determinação dos cortes tomográficos no estudo foram utilizados fios metáticos nas regiões posteriores. Após o exame as mandíbulas foram seccionadas e as medidas diretas de altura e espessura foram obtidas pelo uso de paquímetro digital. Os resultados pelo teste ICC demonstraram não haver diferenças estatisticamente significantes entre as medidas realizadas pelos dois examinadores com paquímetro e as tomografias. Concluiu-se que a TCFC é confiável para realização de medidas na mandíbula e que o tamanho do voxel não interferiu no planejamento cirúrgico. / The use of cone beam computed tomography (CBCT) allows to evaluate the height and thickness of the remaining bone for implant placement. The atresic mandible requires higher level of detail for obtaining measurements. The author in the present study evaluates the influence of the voxel size (0.125 mm and 0.25 mm) in thickness and height measurements using 10 edentulous dry mandibles. For determination of the tomographic study were used metallic wires in the posterior regions. After examining, the mandibles were sectioned and direct measures of height and thickness were obtained through digital caliper. The results by ICC test showed no statistically significant differences between the measurements with caliper and tomograms made by two examiners. It was concluded that CBCT is trusted to carry out measurements in mandible and the voxel size did not affect the surgical planning.
102

Tomografia computadorizada por feixe cônico para detecção de lesões incipientes de furca simuladas em mandíbulas suínas maceradas / Cone beam computed tomography for detection of incipient furcation invasion in pig mandibles

Otávio Shoiti Umetsubo 04 July 2011 (has links)
As radiografias intraorais ilustram bem os estágios de reabsorção periodontal nas regiões interproximais. Entretanto, a sobreposição de estruturas dificulta avaliação da perda óssea nas corticais vestibular e lingual. A tomografia computadorizada por feixe cônico (TCFC) é de elevada importância em várias especialidades odontológicas, tais como implantodontia, avaliação de lesões ósseas, estudo da articulação têmporo-mandibular e cirurgia buco-maxilo-facial. A TCFC também tem tido crescente indicação em outras áreas, como a periodontia e endodontia. O objetivo no presente estudo foi a) estabelecer o protocolo de aquisição mais adequado para a detecção de lesões incipientes de furca simuladas quimicamente; e b) avaliar a reprodutibilidade, sensibilidade e especificidade da TCFC, para a finalidade previamente citada. No presente estudo, foram utilizadas 15 mandíbulas suínas maceradas, que apresentavam o segundo molar íntegro e as corticais adjacentes preservadas As simulações de lesões em região de furca foram feitas com aplicação de ácido perclórico a 70%, em até quatro sítios possíveis em cada mandíbula (vestibular do lado direito, lingual do lado direito, vestibular do lado esquerdo, lingual do lado esquerdo) por um examinador participante que não avaliou as imagens. Nos 60 sitios possíveis, foram escolhidos aleatoriamente 20 para as simulações das lesões. Posteriormente, as mandíbulas foram submetidas à TCFC (i-CAT Next Generation) em dois. protocolos de aquição: voxel 0,2 mm e 0,25 mm, ambos com FOV de 6 cm de altura por 16 cm de diâmetro e com 26,9 segundos de tempo. Dois observadores (radiologistas previamente calibrados) avaliaram os exames duas vezes, em ordem aleatória, sob iluminação controlada. Os observadores foram orientados a direcionar a avaliação das regiões dos segundos molares, e questionados se havia lesão ou não nos sítios avaliados. A interpretação das imagens foi realizada em uma estação de trabalho independente localizada no Laboratório de Imagem em Terceira Dimensão da Faculdade de Odontologia da Universidade de São Paulo, utilizando o software Xoran (Xoran Technologies). A sensibilidade, especificidade e reprodutibilidade da TCFC foram avaliadas nos dois protocolos. A TCFC apresentou especificidade alta, sensibilidade baixa e reprodutibilidade moderada na detecção de lesões incipientes de furca. A influência do tamanho do voxel não foi estatisticamente significativa na detecção destas lesões. / Intraoral radiographs illustrate the stages of resorption in periodontal interproximal regions. However, overlapping structures hinders evaluation of bone loss in the buccal and lingual cortical plates. The cone beam computed tomography (CBCT) is of high importance in various dental specialties such as implantology, evaluation of bone lesions, the study of temporomandibular joint and maxillo-facial surgery. The CBCT has also been increasing indications in other areas, such as periodontics and endodontics. The aim of this study was to establish a) the acquisition protocol most suitable for the detection of incipient furcation invasion chemically simulated and b) assess the reproducibility, sensitivity and specificity of CBCT for the purpose previously mentioned. In this study, 15 pigs macerated mandibles were used, which showed the second molar and the adjacent cortical integrity preserved. Simulated lesions in the furcation area were made with application of 70% perchloric acid, up to four possible sites in each jaw (the right buccal, the right lingual, the left buccal, and left lingual side) by an examiner participant who did not evaluate the images. In the 60 possible sites, 20 were randomly chosen for the simulated lesions. Subsequently, the mandibles underwent cone beam computed tomography (Next Generation i-CAT) in two acquisition protocols: at 0.2 mm and 0.25 mm voxel, both with FOV of 6 cm height by 16 cm in diameter and 26.9 seconds of time. Two observers (calibrated radiologists) evaluated the examinations twice, in random order under controlled lighting. Observers were instructed to direct the evaluation to the regions of the second molars, and they were asked if there were or not injuries on those avaluated sites. Image interpretation was performed on an independent workstation located at the Third Dimension Laboratory of Image in the School of Dentistry, University of São Paulo, using the software Xoran (Xoran Technologies). The sensitivity, specificity and reproducibility of CBCT were assessed in both trials. The CBCT showed high specificity, low sensitivity and moderate reproducibility in the detection of incipient lesions, furcation. The influence of voxel size was not statistically significant in detecting these lesions.
103

\"Estudo comparativo entre a tomografia computadorizada e a tomografia volumétrica na confecção de modelos de prototipagem\" / Comparison of cone beam computerized tomography and multislice computerized tomography for building rapid prototyping models

Mario Sergio Saddy 07 December 2006 (has links)
O objetivo neste estudo foi comparar modelos de prototipagem, originados a partir de dados obtidos em exames de tomografia volumétrica (TV) e tomografia computadorizada (TC), a fim de verificar a precisão de reprodutibilidade destas tecnologias. Uma mandíbula seca foi submetida aos exames de TV (NewTom 9000? QR, Itália) e TC (Select SP-Elscint, Israel). Os dados obtidos nos exames foram manipulados em dois sistemas de tratamento de imagem, o 3D- Analyze (Mayo Clinic, E.U.A.) e o InVesalius (CenPRA, Brasil) e confeccionados protótipos, em duas diferentes tecnologias (SLS - sinterização seletiva a laser e 3DP - impressão tridimensional). A mandíbula seca (padrão ouro) e os oito conjuntos de protótipos gerados, sendo I-TC-Analyze?3DP; II-TC-Invesalius?3DP; III-TC-Analyze?SLS; IVTC- Invesalius-SLS; V-TV-Analyze?3DP; VI-TV-Invesalius?3DP; VIII-TV-Analyze? SLS; VIII-TV-Invesalius-SLS, foram submetidos a processos de engenharia reversa com a finalidade de digitalizar as superfícies dos objetos para uma comparação de cada modelo de prototipagem produzido com o padrão ouro, com precisão de 0,001mm. Os desvios de até 1mm e até 2mm foram calculados, comparados e analisados estatisticamente os erros percentuais. Os modelos de prototipagem rápida originados por meio da obtenção de dados de exames de tomografia computadorizada são mais precisos que os modelos de prototipagem originados por meio de dados de exames de tomografia volumétrica. / The purpose of this study is to compare rapid prototyping models created from cone beam computerized tomography (CBCT) and multislice computerized tomography (CT) data, in order to verify the accuracy of these technologies. A dry skull mandible was submitted in a CBCT (NewTom ? QR, Italy) and CT (Select SP-Elscint, Israel) exams. The tomographies data were processed by two different Medical Image processing systems, 3D-Analyze (Mayo Clinic, U.S.A.) and InVesalius (CenPRA, Brazil). Rapid prototypes models were built in two different rapid prototyping technologies, 3D Printer (3DP) and Selective Laser Sintering (SLS). The dry skull mandible (gold standard) and the eight prototypes, as follows; I-CT-Analyze?3DP; IICT- Invesalius?3DP; III-CT-Analyze?SLS; IV-CT-Invesalius-SLS; V-CBCT-Analyze? 3DP; VI-CBCT-Invesalius?3DP; VIII-CBCT-Analyze?SLS; VIII-CBCT-Invesalius-SLS, were submitted to a reverse engineering process aimed to digitalize the surfaces of the objects to compare each rapid prototype model with the gold standard with a precision of 0.001mm. Percentage deviations errors until 1.0mm and 2.0mm were calculated, compared and statistically analyzed. The prototyped models obtained with multislice computerized tomography data shows more accuracy than those obtained with data from cone beam computerized tomography.
104

Avaliação da raiz mesiovestibular de primeiros molares superiores para detecção do canal mesiopalatino com o uso da tomografia computadorizada de feixe cônico

Fontana, Mathias Pante January 2017 (has links)
Os molares superiores são um dos grupos dentários que mais recebem tratamentos endodônticos e apresentam grande complexidade anatômica nos seus sistemas de canais radiculares. A presença de um canal mesiopalatino (MP) na raiz mesiovestibular é um achado bastante comum e a sua não detecção está relacionada com um alto índice de insucessos na terapia endodôntica. Recentemente, a tomografia computadorizada de feixe cônico (TCFC) vem ganhando destaque na avaliação do canal MP pela sua capacidade de fornecer informações detalhadas e em três dimensões, sendo considerada o melhor método de imagem para essa investigação in vivo. Desta forma, o objetivo desta tese foi pesquisar a prevalência e simetria do número de canais da raiz mesiovestibular em primeiros molares superiores homólogos, por meio da TCFC, assim como, analisar o uso dos filtros de refinamento de imagem para esta investigação. Para o primeiro objetivo, desenvolveu-se uma pesquisa com 264 pacientes possuindo o primeiro molar superior bilateralmente. Foi encontrada simetria em 78,79% dos pacientes, sendo que o canal MP esteve presente bilateralmente em 67,42%. Do total de 528 dentes avaliados, 78% apresentaram o canal MP não havendo correlação da sua presença com sexo e faixa etária (p > 0,05). Para o segundo objetivo, 30 exames de TCFC foram avaliados com cinco diferentes filtros (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low e Angio Sharpen High) além das imagens originais (sem filtro). Todos os filtros apresentaram altos índices de acurácia (> 83,3%), sensibilidade (> 90%) e especificidade (> 62%), sem diferença estatística (p > 0,05). Entretanto, quando o nível de certeza foi avaliado, os filtros Angio Sharpen High e Sharpen apresentaram os piores resultados, com diferença significativa para as imagens Originais (p <0,05). Os resultados das pesquisas conduzidas permitem concluir que o canal MP é uma condição altamente prevalente e a sua simetria bilateral é frequente. O emprego de filtros de imagem da TCFC não influenciou a detecção do canal MP, entretanto os filtros de maior realce devem ser evitados pois reduzem a certeza do diagnóstico. / The upper molars are the dental group that most receives endodontic treatments and presents great anatomical complexity of their root canal systems. The presence of a second mesiobuccal canal (MB2) is a common finding and its non-detection is related to a high failure rate in endodontic therapy. Recently, cone-beam computed tomography (CBCT) has been highlighted in the MB2 evaluation for its ability to provide detailed and three-dimensional information, and is considered the best imaging method for such investigation in vivo. Thus, the aim of this thesis was to investigate the prevalence and symmetry of the root canal numbers from the mesiobuccal root of first homologous upper molars, as well as to evaluate the use of CBCT image filters for that purpose. For the first objective, a research was developed with 264 patients having the first upper molar bilaterally. Symmetry was found in 78.79% patients, and the MB2 was bilaterally present in 67.42%. Out the total of 528 teeth evaluated, 78% presented the MB2, with no correlation with sex and age group (p > 0.05). For the second objective, 30 CBCT scans were evaluated with five different filters (Original, Smooth, Sharpen, Sharpen Mild, Angio Sharpen Low and Angio Sharpen High) in addition to the original images (none filter). All filters presented high levels of accuracy (> 83.3%), sensitivity (> 90%) and specificity (> 62%), with no statistical difference (p > 0.05). However, when the level of certainty was evaluated, Angio Sharpen High and Sharpen filters presented the worst results, with significant difference for Original images (p < 0.05). The results of the conducted studies allow us to conclude that the MB2 is a highly prevalent condition and its bilateral simmetry is frequent. The use of CBCT image filters did not influence the MB2 detection, however higher enhancement filters should be avoided because they reduce the certainty of the diagnosis.
105

The comparison of different rapid maxillary expansion devices from periodontal tissue health and root resorption perspectives

Facciolo, Joseph 25 October 2017 (has links)
INTRODUCTION: Utilization of rapid maxillary expansion (RME) is common for the correction of sagittal discrepancies in orthodontic treatment. RME appliances will transmit a compressive force to the periodontal support structures. This resultant force can lead to resorption of the dento-alveolar structures leading to unwanted dental movements. The purpose of this retrospective study was to compare changes from a periodontal and root resorption perspective by means of computer tomography with tooth-borne and bonded expanders. METHODS: The sample comprised of cone beam computed tomography and spiral CT images of 41 subjects, 12 to 17 years old, with unilateral or bilateral posterior crossbites. 20 subjects treated previously with a bonded expander and 21 with a banded expander. Pre and post-treatment images were digitized and landmarks were identified to measure buccal and lingual cortex thickness, alveolar height, root length and angulation by means of a computerized method. RESULTS: RME with banded and bonded expanders have similar effects from periodontal and root resorption perspectives. Changes include increasing thickness of lingual alveolar bone 0.2 to 0.7 mm, decreases in buccal bone width 0.1 to 0.5 mm; and decreases in alveolar height 0.1 to 0.9 mm and root length 0.3 to 1.0mm of each support teeth. CONCLUSIONS: RME with banded and bonded expanders exhibited similar changes post-expansion and these variables should not play a role in selection of the type of device.
106

Foraminas acessórias da região anterior da maxila em tomografia computadorizada de feixe cônico / Additional foraminas in anterior maxilla through cone beam computed tomography

Ikuta, Carla Renata Sanomiya 27 October 2017 (has links)
Por meio do exame tridimensional de Tomografia computadorizada de feixe cônico (TCFC) é possível avaliar a área de interesse previamente aos procedimentos com maior precisão. As variações anatômicas são estruturas que devem ser consideradas para a realização de cirurgias, como a foramina acessória da região anterior da maxila (FARAM). O objetivo principal do presente estudo foi avaliar a FARAM, em 150 exames de TCFC, obtidas no aparelho ICat Classic®. Por meio do programa ICat Vision® foram mensuradas o diâmetro, a distância da FARAM ao forame incisivo (FARAM-FI), da FARAM ao rebordo alveolar vestibular (FARAM-RAV) e da FARAM a sutura intermaxilar (FARAM-SI). Também foi avaliada a trajetória dos canais ósseos formados a partir da FARAM. Nos pacientes dentados, foram localizados por meio da área dos dentes: incisivo central, incisivo lateral e caninos. Foi realizada a correlação entre a presença da FARAM e o gênero e a idade. Dos 150 exames, a FARAM estava presente em 21 exames (14%). Destes, dez pacientes eram edêntulos na região de interesse de estudo e não foi possível localizar a foramina em relação aos dentes. Nenhum exame apresentou a FARAM relacionada ao incisivo central, em sete estavam relacionadas ao incisivo lateral e em quatro estavam relacionadas ao canino. Nenhum exame apresentou a FARAM bilateralmente, sendo que treze foram localizadas no lado direito e oito do lado esquerdo. O diâmetro médio da FARAM foi de 1,57 ± 0,38 mm. As médias das distâncias de FARAM-RAV foi de 11,65 ± 3,34 mm, FARAM-FI foi de 8,86 ± 2,72 mm e FARAM-SI, foi de 6,37 ± 2,9 mm. A trajetória do canal ósseo mais comum foi ascendente/oblíqua em direção a região anterior do assoalho da cavidade nasal. A correlação entre a presença da FARAM e o gênero foi estaticamente significante para os homens (p=0,055) no teste do qui-quadrado. No entanto, não foi estatisticamente significante para a idade. / Through cone beam computed tomography (CBCT) is possible to evaluate the region of interest before surgical procedures in tridimensional view. Anatomical variations should be considered for performing surgeries, as the additional foraminas in anterior maxilla (AFAM). The main aim of the present study is evaluate AFAM in 150 CBCT exams, obtained through ICat Classic® device. In ICat Vision® software, the diameter, the distance from the AFAM to the incisive foramen (AFAM-IF), AFAM to the vestibular alveolar ridge (AFAM-VAR) and AFAM intermaxillary suture (AFAM-IS) were measured. It was also evaluated the trajectory of the bony canals related to AFAM. In dentate patients, AFAM was located through the teeth area: central incisor, lateral incisor and canines. The correlation between the presence of FARAM and gender and age was investigated. The AFAM was presented in 21 exams (14%). In the positive exams, 10 patients were edentulous in the region of study interest and it was not possible to locate the foramen in relation to the teeth. Any exam presented the AFAM related to the central incisor, in seven were related to the lateral incisor and in four were related to the canine. Any exam presented the AFAM bilaterally, of which thirteen were located on the right side and eight on the left side. The mean diameter of the AFAM was 1.57 ± 0.38 mm. The distance of the AFAM-VAR 11.65 ± 3.34 mm, AFAMIF was 8.86 ± 2.72 mm and AFAM-IS was 6.37 ± 2.9 mm. The most common bone canal trajectory was upward/ oblique to the anterior region of the floor of the nasal cavity. The correlation between the presence of AFAM and the gender was statically significant for males (p=0.055) in the chi-square test. However, it was not statistically significant for age.
107

Tomografia computadorizada por feixe cônico para detecção de lesões incipientes de furca simuladas em mandíbulas suínas maceradas / Cone beam computed tomography for detection of incipient furcation invasion in pig mandibles

Umetsubo, Otávio Shoiti 04 July 2011 (has links)
As radiografias intraorais ilustram bem os estágios de reabsorção periodontal nas regiões interproximais. Entretanto, a sobreposição de estruturas dificulta avaliação da perda óssea nas corticais vestibular e lingual. A tomografia computadorizada por feixe cônico (TCFC) é de elevada importância em várias especialidades odontológicas, tais como implantodontia, avaliação de lesões ósseas, estudo da articulação têmporo-mandibular e cirurgia buco-maxilo-facial. A TCFC também tem tido crescente indicação em outras áreas, como a periodontia e endodontia. O objetivo no presente estudo foi a) estabelecer o protocolo de aquisição mais adequado para a detecção de lesões incipientes de furca simuladas quimicamente; e b) avaliar a reprodutibilidade, sensibilidade e especificidade da TCFC, para a finalidade previamente citada. No presente estudo, foram utilizadas 15 mandíbulas suínas maceradas, que apresentavam o segundo molar íntegro e as corticais adjacentes preservadas As simulações de lesões em região de furca foram feitas com aplicação de ácido perclórico a 70%, em até quatro sítios possíveis em cada mandíbula (vestibular do lado direito, lingual do lado direito, vestibular do lado esquerdo, lingual do lado esquerdo) por um examinador participante que não avaliou as imagens. Nos 60 sitios possíveis, foram escolhidos aleatoriamente 20 para as simulações das lesões. Posteriormente, as mandíbulas foram submetidas à TCFC (i-CAT Next Generation) em dois. protocolos de aquição: voxel 0,2 mm e 0,25 mm, ambos com FOV de 6 cm de altura por 16 cm de diâmetro e com 26,9 segundos de tempo. Dois observadores (radiologistas previamente calibrados) avaliaram os exames duas vezes, em ordem aleatória, sob iluminação controlada. Os observadores foram orientados a direcionar a avaliação das regiões dos segundos molares, e questionados se havia lesão ou não nos sítios avaliados. A interpretação das imagens foi realizada em uma estação de trabalho independente localizada no Laboratório de Imagem em Terceira Dimensão da Faculdade de Odontologia da Universidade de São Paulo, utilizando o software Xoran (Xoran Technologies). A sensibilidade, especificidade e reprodutibilidade da TCFC foram avaliadas nos dois protocolos. A TCFC apresentou especificidade alta, sensibilidade baixa e reprodutibilidade moderada na detecção de lesões incipientes de furca. A influência do tamanho do voxel não foi estatisticamente significativa na detecção destas lesões. / Intraoral radiographs illustrate the stages of resorption in periodontal interproximal regions. However, overlapping structures hinders evaluation of bone loss in the buccal and lingual cortical plates. The cone beam computed tomography (CBCT) is of high importance in various dental specialties such as implantology, evaluation of bone lesions, the study of temporomandibular joint and maxillo-facial surgery. The CBCT has also been increasing indications in other areas, such as periodontics and endodontics. The aim of this study was to establish a) the acquisition protocol most suitable for the detection of incipient furcation invasion chemically simulated and b) assess the reproducibility, sensitivity and specificity of CBCT for the purpose previously mentioned. In this study, 15 pigs macerated mandibles were used, which showed the second molar and the adjacent cortical integrity preserved. Simulated lesions in the furcation area were made with application of 70% perchloric acid, up to four possible sites in each jaw (the right buccal, the right lingual, the left buccal, and left lingual side) by an examiner participant who did not evaluate the images. In the 60 possible sites, 20 were randomly chosen for the simulated lesions. Subsequently, the mandibles underwent cone beam computed tomography (Next Generation i-CAT) in two acquisition protocols: at 0.2 mm and 0.25 mm voxel, both with FOV of 6 cm height by 16 cm in diameter and 26.9 seconds of time. Two observers (calibrated radiologists) evaluated the examinations twice, in random order under controlled lighting. Observers were instructed to direct the evaluation to the regions of the second molars, and they were asked if there were or not injuries on those avaluated sites. Image interpretation was performed on an independent workstation located at the Third Dimension Laboratory of Image in the School of Dentistry, University of São Paulo, using the software Xoran (Xoran Technologies). The sensitivity, specificity and reproducibility of CBCT were assessed in both trials. The CBCT showed high specificity, low sensitivity and moderate reproducibility in the detection of incipient lesions, furcation. The influence of voxel size was not statistically significant in detecting these lesions.
108

The impact of luminance on localizing the inferior alveolar canal on cone beam computed tomography

Orgill, Joshua J. 01 May 2019 (has links)
Introduction: The use of CBCT to visualize the relationship between the inferior alveolar canal and the mandibular third molar roots continues to grow as it is becoming the standard of care. It becomes important to understand the impact that luminance, one of the factors that affects the viewing conditions of digital images, has on appropriately assessing the third molar-canal relationship. To date, no study has assessed the impact of luminance on visualizing anatomic structures on CBCT. The aim of this study is to determine if there is a difference in the ability to appropriately assess the root development and the third molar-canal relationship on a medical grade monitor with four different luminance settings on CBCT. Materials and methods: 285 scans were randomized and evaluated by three calibrated and masked evaluators. The evaluations were completed on a Barco MDNC-3321 Nio Color 3MP monitor (Kortrijk, Belgium) monitor at four different luminance settings; 200 cd/m2, 300 cd/m2, 400 cd/m2, and 500 cd/m2. The gold standard was established by two board-certified oral and maxillofacial radiologists. All evaluations were performed in a controlled subdued environment lighting of less than 15 lux. There was a washout period of at least one week between each of the four evaluations by an observer. Results: The accuracy of two of the three evaluators was substantial to almost perfect independent of luminance. None of these assessments showed any statistical significance (P = 0.05). The accuracy of one evaluator was moderate to almost perfect for all evaluations with one assessment of one canal showing statistical significance (P = 0.05). Conclusion: There is no difference in the ability to appropriately assess the third molar canal relationship or the root development of third molars on a medical grade monitor at luminance settings between the range of 200 cd/m2 and 500 cd/m2 when viewed in a dimly lit room.
109

Evaluation and Comparison of Periapical Healing Using Periapical Films and Cone Beam Computed Tomography: Post-Treatment Follow Up

Polinsky, Adam S 01 January 2019 (has links)
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.
110

Reliability of 3D-printed mandibles constructed from CBCT volumes of different voxel sizes

Vijayan, Suvendra 01 May 2018 (has links)
Objectives: The aim of the current study is to establish the reliability of linear cephalometric measurements made on mandibles and their respective 3D printed models created from different voxel resolutions from a cone beam CT machine. Materials and methods: Ten dry mandibles obtained from the Department of Oral Pathology, Radiology and Medicine at The University of Iowa College Of Dentistry were used for this study. All mandibles were scanned on the i-CAT FLX cone beam CT machine (Imaging Sciences International, LLC, Pennsylvania, USA) using voxel resolutions of .30mm, .25mm and .20 mm in a 16cm x 8cm field of view using 360° rotation. The 3D models were reconstructed and saved as .STL files using 3D Slicer software and send to a 3D printer for printing. Two observers measured the 10 mandibles and 30 3D printed models. The measurement were repeated on 50% of the samples after at least one week interval. Cronbach’s alpha and intraclass correlation coefficient were calculated to measure reliability. Results: Good to excellent interobserver and intraobserver reliability was achieved across most of the measurements. There was no difference in reliability across models made from different voxel sizes. Conclusion: The current study successfully showed that the reliability of measurements made on 3D printed models of dry skull mandibles created using fused deposition modeling technique using images of different voxel sizes from an i-CAT FLX CBCT machine are valid, reproducible, and reliable and can be used for diagnostic and clinical purposes.

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