Abstract This study aimed to assess the influence of the file format on the image quality parameters (image noise, brightness, and uniformity) of periapical radiographs acquired with different digital systems. Radiographic images of an acrylic phantom were acquired with two digital systems - Digora Toto and Express, and exported into five different file formats - TIFF, BMP, DICOM, PNG, and JPEG. Image noise, image brightness (mean of gray values), and image uniformity (standard deviation of gray values) were evaluated in all images. A two-way analysis of variance with Tukey’s test as a post-hoc test was used to compare the results, considering the file formats and radiographic systems as the studied factors. A significance level of 5% was adopted for all analyses. The DICOM image file format presented lower image noise, higher brightness (higher mean gray values), and greater image uniformity (p<0.001) than the other file formats, which did not differ from each other for both digital radiography systems (p>0.05). The Express system revealed lower image noise and greater image uniformity than the Digora Toto system regardless of the image file format (p<0.001). Moreover, the Express showed higher brightness than the Digora Toto for all image file formats (p<0.001), except for the DICOM image file format, which did not significantly differ between the digital radiography systems tested (p>0.05). The DICOM image file format showed lower image noise, higher brightness, and greater image uniformity than the other file formats (TIFF, BMP, PNG, and JPEG) in both digital radiography systems tested.

Resumo Este estudo teve como objetivo avaliar a influência do formato do arquivo nos parâmetros de qualidade de imagem (ruído de imagem, brilho e uniformidade) de radiografias periapicais adquiridas com diferentes sistemas digitais. As imagens radiográficas de um fantoma de acrílico foram adquiridas com dois sistemas digitais - Digora Toto e Express, e exportadas em cinco formatos de arquivo diferentes - TIFF, BMP, DICOM, PNG e JPEG. O ruído da imagem, o brilho da imagem (média dos valores de cinza) e a uniformidade da imagem (desvio padrão dos valores de cinza) foram avaliados em todas as imagens. A análise de variância (ANOVA) bidirecional com o teste post-hoc de Tukey foi aplicada para comparar os resultados, considerando os formatos de arquivo e os sistemas radiográficos como os fatores estudados. Um nível de significância de 5% foi adotado para todas as análises. O formato de arquivo de imagem DICOM apresentou menor ruído de imagem, maior brilho (maiores valores médios de cinza) e maior uniformidade de imagem (p<0,001) do que os outros formatos de arquivo, que não diferiram entre si para ambos os sistemas de radiografia digital (p>0,05). O sistema Express apresentou menor ruído de imagem e maior uniformidade de imagem que o sistema Digora Toto, independentemente do formato do arquivo de imagem (p<0,001). Além disso, o Express mostrou maior brilho do que o Digora Toto para todos os formatos de arquivo de imagem (p<0,001), exceto para o formato de arquivo de imagem DICOM, que não diferiu significativamente entre os sistemas de radiografia digital testados (p>0,05). O formato de arquivo de imagem DICOM mostrou menor ruído de imagem, maior brilho e maior uniformidade de imagem do que os outros formatos de arquivo (TIFF, BMP, PNG e JPEG) em ambos os sistemas de radiografia digital testados.

Abstract The study aimed to assess the influence of excessive use of a photostimulable phosphor plate (PSP) on the density, image noise, and contrast of radiographs. For that, radiographs of an acrylic block were acquired with a PSP of the Express intraoral system to assess the density and image noise. Initially, five images were obtained and exported (first group). After 400 exposures to X-rays and scannings of PSP, other five images were obtained and exported (second group). The same procedure was done after 800 (third group), 1200 (fourth group), 1600 (fifth group), and 2000 acquisitions (sixth group), resulting in 30 images to be evaluated. The mean and standard deviation of the gray values were calculated for the images using the ImageJ software. For contrast analysis, radiographs of an aluminum step-wedge were acquired with a new PSP following the same acquisition intervals. The percentage of contrast variation was calculated. Another two unused PSP receptors were employed to evaluate the method’s reproducibility. The comparison of the results among the acquisition groups was performed with one-way Analysis of Variance (α=0.05). Intraclass Correlation Coefficient (ICC) assessed the reproducibility of the receptors. Image noise did not differ among the groups (p>0.05). There was a slight increase in density after 400 acquisitions and a slight difference in contrast for all acquisition groups without a pattern of increase or decrease (p<0.05). ICC showed excellent reliability for the methods. Therefore, excessive PSP use slightly affected the radiograph’s density and contrast.

Resumo Objetivou-se avaliar a influência do uso excessivo de uma placa de fósforo fotoestimulável (PSP) na densidade, ruído e contraste das radiografias. Foram adquiridas radiografias de um bloco de acrílico com uma PSP do sistema intraoral Express para avaliar a densidade e o ruído da imagem. Inicialmente, cinco imagens foram obtidas e exportadas (primeiro grupo). Após 400 exposições aos raios X e escaneamentos, outras cinco imagens foram obtidas e exportadas (segundo grupo). O mesmo procedimento foi feito após 800 (terceiro grupo), 1200 (quarto grupo), 1600 (quinto grupo) e 2000 aquisições (sexto grupo), resultando em 30 imagens a serem avaliadas. A média e o desvio padrão dos valores de cinza foram calculados para as imagens usando o software ImageJ. Para análise de contraste, foram adquiridas radiografias de uma escala de alumínio com uma nova PSP seguindo os mesmos intervalos de aquisição. A porcentagem de variação do contraste foi calculada. Outras duas PSP sem uso prévio foram utilizadas para avaliar a reprodutibilidade dos métodos. A comparação dos resultados entre os grupos de aquisição foi realizada pela Análise de Variância one-way (α=0,05). O Coeficiente de Correlação Intraclasse (ICC) avaliou a reprodutibilidade dos receptores. O ruído da imagem não diferiu entre os grupos (p>0,05). Houve um leve aumento na densidade após 400 aquisições e uma pequena diferença no contraste para todos os grupos de aquisição sem padrão de aumento ou diminuição (p<0,05). O ICC mostrou excelente confiabilidade para os métodos. Portanto, o uso excessivo da PSP afetou levemente a densidade e o contraste radiográfico.

Resumen: Evaluar la percepción y los sentimientos manifestados por profesores y estudiantes de odontología sobre la educación a distancia durante la pandemia por COVID-19. 50 profesores y 52 estudiantes informaron las percepciones e implicaciones del aprendizaje a distancia impuestas por motivo de la pandemia de COVID-19. Respuestas de los participantes fueron analizadas utilizando el método cualitativo-cuantitativo del discurso del sujeto colectivo. Respuestas se agruparon en ideas centrales, obteniendo el discurso del sujeto colectivo y fueron distribuidas en frecuencia absoluta y relativa. Ideas centrales similares entre profesores y estudiantes sobre el aprendizaje a distancia fueron: a) es adecuado para cursos didácticos; b) limitado para cursos de laboratorio y clínicos; c) presenta dificultades devido al acceso a Internet. Específicamente para profesores: a) complemento a la docencia en el aula; b) aumenta el estrés devido a la curva de aprendizaje con tecnologías digitales; c) dificultad para conciliar las clases con las actividades domésticas; d) preocupaciones con la motivación y la interacción con los estudiantes; e) las clases asincrónicas favorecen la fijación del conocimiento y las clases sincrónicas favorecen la interacción con los estudiantes; f) métodos de evaluación poco fiables; y g) preocupación por volver a las clases presenciales. Para los estudiantes: a) se aplicó a todos los cursos; b) desmotivador fundamental para orientar los estudios; c) compromiso de los profesores; d) conferencias largas; e) actividades escolares excesivas; f) difícil control y evaluación de asistencia; g) la comodidad de estar en casa; y h) impacto en la investigación. Profesores consideraron el aprendizaje a distancia como una oportunidad de aprendizaje sobre cómo utilizar las tecnologías digitales, pero demasiado limitado para las actividades de laboratorio y clínicas y la interacción con los estudiantes. Estudiantes lo encontraron desalentador debido a la ausencia de clases prácticas y al exceso de actividades escolares.

Abstract The objective of this study was to evaluate perception and feelings experienced by dentistry professors and students about distance learning during the COVID-19 pandemic. Fifty professors and fifty- two students reported the perceptions and implications of distance learning imposed by the pandemic of COVID-19. The participants' answers were analyzed using the qualitative-quantitative method of the collective subject's discourse. The answers were summarized in central ideas, distributed in absolute and relative frequency. The answers with similar central ideas were grouped, obtaining the discourse of the collective subject. The similar central ideas about distance learning addressed by professors and students were: suitable for didactic courses; limited laboratory and clinical courses, and internet access difficulties. Specifically for professors: a complement to classroom teaching; stress and learning with digital technologies; difficulty in reconciling classes with domestic activities; concerns with motivation and interaction with students; asynchronous lectures favor knowledge fixation, and synchronous lectures favor interaction with students; unreliable assessment methods; concern about returning to face-to-face classes. For the students: it was applied to all courses; demotivating; fundamental to guide studies; professors' commitment; long lectures; excessive school activities; difficult attendance control and evaluation; the comfort of being at home; impact on research. Professors considered distance learning as a learning opportunity on how to use digital technologies but too limited for lab and clinical activities and interaction with students. Students found it discouraging due to the absence of practical classes and excessive school activities.

Resumo O objetivo nesse estudo foi avaliar o efeito da ferramenta de redução de artefato (FRA) na expressão de artefatos em diferentes regiões de um dente restaurado com diferentes tipos de pinos metálicos. Foram usados alvéolos (regiões anterior e posterior) de uma mandíbula e um dente unirradicular. Imagens de tomografia computadorizada de feixe cônico do dente sem pino metálico intracanal e com pinos de cobalto-cromo (Co-Cr), níquel-cromo (Ni-Cr) ou prata-paládio (Ag-Pd) foram individualmente obtidas, com 2 condições de FRA: desativada e ativada. Em uma reconstrução axial, linhas de interesse (LOIs) foram definidas ao redor do canal: 4 em direções oblíquas (mésio-vestibular, disto-vestibular, mésio-lingual e disto-lingual) e 4 em direções ortogonais (mesial, distal, vestibular e lingual). A expressão dos artefatos de endurecimento do feixe foi determinada pelo cálculo da diferença na média dos valores de cinza (DMVC) entre os grupos experimental e controle para cada LOI. Não houve diferença significativa nos valores de DMVC entre as condições “sem FRA” e “com FRA” para nenhuma das LOIs, nem na região anterior nem na região posterior da mandíbula (p>0,05), para os grupos Ni-Cr e Co-Cr. Para o Ag-Pd, diferenças significativas nos valores de DMVC foram observadas entre “sem FRA” e “com FRA” para a maioria das LOIs (p<0,05), principalmente nas direções oblíquas na região anterior, e na direção mesio-distal na região posterior. A FRA atuou principalmente em artefatos hipodensos (DMVC negativos). A eficácia da FRA disponível no aparelho de TCFC OP300 variou de acordo com o material do pino testado. Ela foi efetiva na redução da expressão de artefatos originados por pinos de Ag-Pd, principalmente nas regiões do dente afetadas por artefatos hipodensos, independentemente da região mandibular.

Abstract This study aimed to assess the effect of the MAR tool on the expression of artefacts in different regions of a tooth restored with different types of metal posts. Alveolar sockets (anterior, and posterior region) of a mandible and an unirradicular tooth were used. Cone beam computed tomography scans of the tooth without a metal post, and with cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), or silver-palladium (Ag-Pd) were individually obtained, with 2 MAR conditions: disabled, and enabled. In an axial reconstruction, lines of interest (LOIs) were set around the canal: 4 in oblique (mesiobuccal, distobuccal, mesiolingual, distolingual) directions, and 4 in orthogonal (mesial, distal, buccal, lingual) directions. Beam-hardening artefacts expression was determined by calculating the difference in the mean of gray values (DMGV) between the experimental and control groups for each LOI. There was no significant difference in the DMGV values between “without MAR” and “with MAR” for any LOI, in neither anterior nor posterior mandible (p>0.05), for the Ni-Cr and Co-Cr groups. For the Ag-Pd, significant differences in the DMGV values were observed between “without MAR” and “with MAR” for most LOIs (p<0.05), mainly in oblique directions in the anterior region, and mesio-distal direction in the posterior region. MAR acted mostly in hypodense artefacts (negative DMGV). The effectiveness of the MAR tool of the OP300 CBCT unit varied according to the post material tested. It was effective in reducing the expression of artefacts raised by the Ag-Pd post, mainly in the tooth regions affected by hypodense artefacts, regardless of the mandibular region.

Abstract This study aimed to assess the microstructure, chemical composition, and image quality of different photostimulable phosphor plates (PSP). Four PSP systems, Express®, Digora®, VistaScan®, and Apixia,® were assessed. Five radiographs of a homogeneous acrylic phantom were obtained with the PSP of each system, to acquire a total of 20 images. The images were objectively evaluated for uniformity using mean grey and standard deviation (SD) of their grey values. PSP receptors were analyzed using scanning electron microscopy (SEM) to determine the thickness of the granule layer and the size of the granules. The chemical composition of the PSP receptors was analyzed using total reflection X-ray fluorescence (TXRF). VistaScan showed more uniform and higher density images than the other tested systems (p < 0.05), as well as the lowest SD of grey values (p < 0.05). Regarding the microstructure of the receptors, Digora and VistaScan had thicker granule layers than Express and Apixia, and VistaScan had smaller granules than Digora and Express (p < 0.05). Fourteen chemical elements were detected in the receptors, with barium being the element with the highest concentration in all PSP systems. The microstructure, chemical composition, and image quality varied among all four PSP receptors studied. VistaScan receptors showed the smallest variation in granule size, one of the thickest granule layers, and the most uniform and least noisy images.

RESUMEN: El objetivo de este estudio fue evaluar el uso y la experiencia con herramientas de comunicación digital entre profesores y estudiantes de odontología para adaptarse al aprendizaje a distancia durante la pandemia Covid-19. Novecientos noventa y cinco participantes (479 profesores y 516 estudiantes de odontología) de países de diferentes regiones de América del Norte, América Latina, Brasil, Europa, Asia, Oceanía y Oriente Medio respondieron un cuestionario sobre motivación/ estrés/ansiedad; práctica con tecnologías digitales; tecnologías de comunicación sincrónicas/asincrónicas (dificultades/beneficios), y cuáles continuarían usando al regresar a la universidad. Los datos se analizaron mediante las pruebas Chi-cuadrado y exacta de Fisher (α=0,05). La motivación se vio más afectada entre las profesoras, estudiantes y brasileños (p<0,05). La preocupación por el futuro académico fue mayor entre las estudiantes, hasta los 30 años, de América Latina y Brasil, y menor para el profesorado europeo (p<0,05). El estrés fue mayor para el estudiantado de pregrado de Latinoamérica y Brasil hasta los 20 años (p<0.05). El profesorado europeo utilizó más servicios de videoconferencia sincrónica para clases y consultas, mientras que el brasileño utilizó más aplicaciones de mensajería de texto para consultas (p<0,05). El profesorado latinoamericano utilizó más encuestas para evaluación (p<0.05). El profesorado brasileño indicó que utilizaría “reuniones en línea” y “servicios de encuestas” cuando regresaran a la presencialidad, mientras que el profesorado/ estudiantado europeo utilizaría “correo electrónico” (p<0,05). El profesorado de Asia/ Oceanía/Medio Oriente y profesorado/estudiantado de Brasil indicó que "las actividades remotas eran importantes para que el estudiantado no estuviera inactivo" (p<0,05). Se relizaron esfuerzos para adaptar la enseñanza de la Odontología al aprendizaje a distancia durante la pandemia de COVID-19. Sin embargo, las tecnologías utilizadas y las experiencias difirieron entre profesores y estudiantes.

ABSTRACT: The objective of this study was to assess the use and experience with digital communication tools among dentistry professors and students to adapt to distance learning during the Covid-19 pandemic. Nine hundread and ninety five participants (479 dentistry professors and 516 students) from countries in North America, Latin America, Brazil, Europe, Asia, Oceania, and the Middle East answered a questionnaire about motivation/stress/anxiety; practice with digital technologies; synchronous/asynchronous communication technologies (difficulties/benefits), and which ones would they prefer using when returning to college. Data were analyzed by the Chi-square test and Fisher's exact (α=0.05). Motivation was more affected among the female professors, male students, and Brazilians (p<0.05). Concern about the academic future, was higher among female students, up to 30 years old, from Latin America and Brazil, and lower for European professors (p<0.05). Anxiety and stress were higher for undergraduate students up to 20 years old from Latin America and Brazil (p<0.05). European professors used more synchronous videoconferencing services for lectures/questions, while Brazilians used more text messaging applications for answering questions (p<0.05). Latin American professors used more surveys for evaluation (p<0.05). Brazilian professors indicated that they would use "online meetings" and "survey administration services" when returning to face-to-face activities and European professors/students would use "email" (p<0.05). Professors from Asia/Oceania/Middle East and professors/students from Brazil indicated "remote activities were important for students not to be inactive" (p<0.05). Efforts were made to adapt Dentistry's teaching to distance learning during the COVID-19 pandemic. However, the technologies used for this, feelings, and experiences differed between professors and students.

ABSTRACT: Panoramic radiography has clinical importance in several dental specialties. The objective of this study was to evaluate the influence of professionals’ experience and patient characteristics (age group and dental absence) in the prevalence of errors and the number of retakes in the panoramic radiography.771 panoramic radiographs were evaluated and classified according to the group of patients (children, dentulous adults, total edentulous adults, and anterior edentulous adults) and professionals who performed the technique (novice and experienced). The association between frequency and type of error, group of patients, professionals’ experience, and number of retakes was performed by the Chi-square and Fisher’s exact test (a=0.05). There was no significant association between the frequency of errors or retakes of the radiograph s and the professionals’ experience or patients’ characteristics (p<0.05). The errors “turned head” and “tongue not against the palate,” “chin tipped low”, “chin not resting on the support,” “patient movement during exposure,” and “lead apron artifact” showed significantly higher frequency of retake (p<0.05). The most frequent type of error was due to the failure to position the tongue against the palate for all patients and both groups of professionals. The frequency of errors in the panoramic radiography occurs regardless of the professionals’ experience, and age and dental absence of the patients. Error occurs mainly due to the lack of patient collaboration, and the examination is rarely repeated by the professionals.

RESUMEN: La radiografía panorámica es de importancia clínica en varias especialidades dentales. El objetivo de este estudio fue evaluar la experiencia de los profesionales y las características de los pacientes (grupo etario y ausencia dentaria) en la prevalencia de errores y el número de repeticiones en la radiografía panorámica.771 radiografías panorámicas fueron evaluadas y clasificadas según la grupo de pacientes (niños, adultos desdentados, adultos desdentados totales y adultos desdentados anteriores) y profesionales que realizaron la técnica (novatos y experimentados). La asociación entre frecuencia y tipo de error, grupo de pacientes, experiencia de los profesionales y número de repeticiones se realizó mediante la prueba de Chicuadrado y exacta de Fisher (a = 0,05). No hubo asociación significativa entre la frecuencia de errores o repetición de las radiografías y la experiencia de los profesionales o las características de los pacientes (p <0,05). Los errores "cabeza girada" y "lengua no contra el paladar", "mentón inclinado hacia abajo", "mentón no apoyado en el soporte", "movimiento del paciente durante la exposición" y "artefacto del delantal de plomo" mostraron una frecuencia de repetición significativamente mayor (p < 0,05). El error más frecuente se debió a la falta de posicionamiento de la lengua contra el paladar para todos los pacientes y en ambos grupos de profesionales. La frecuencia de errores en la radiografía panorámica ocurre independientemente de la experiencia de los profesionales, edad y ausencia dentaria del pacientes. El error se produce principalmente por la falta de colaboración del paciente, y los profesionales rara vez repiten el examen.

ABSTRACT: This study evaluated influence of addition of lead foil coupled to different types of digital receptors on image noise and on diagnosis of fractured instruments in teeth without and with root filling. Twenty-six molars had their root canals (n=67) cleaned and shaped and were divided into groups with and without root filling and with and without fractured instruments. Images were acquired in PSP and CMOS sensor, with and without addition of a lead foil coupled to the digital receptors. Diagnostic values were obtained by the area under the ROC curve, and one-way ANOVA compared the groups. Noise in images was measured by the standard deviation of mean gray values in images with and without the lead foil, and compared by two-way ANOVA (a=0.05). Addition of lead foil did not interfere in the diagnostic accuracy for both digital systems (p>0.05) and did not decrease noise in the images (p>0.05). However, independently of the addition of the lead foil, the phosphor-storage plate presented higher noise compared to the sensor (p ?0.05). Addition of lead foil to the digital receptor did not interfere in image noise and with the diagnostic accuracy for detecting fracured endodontic instrument in ex-vivo conditions.

RESUMEN: Este estudio evaluó la influencia de láminas de plomo acopladas a diferentes tipos de receptores digitales sobre el ruido de la imagen y el diagnóstico de instrumentos fracturados en dientes sin y con obturación radicular. Se limpiaron y moldearon 26 molares (n = 67), se dividieron en grupos con y sin relleno radicular y con y sin instrumentos fracturados. Las imágenes se adquirieron en el sensor PSP y CMOS, con y sin adición de una lámina de plomo acoplada a los receptores digitales. Los valores diagnósticos se obtuvieron por el área bajo la curva ROC y con ANOVA de una vía comparó los grupos. El ruido en las imágenes se midió mediante la desviación estándar de los valores medios de gris en las imágenes con y sin la lámina de plomo, y se comparó mediante ANOVA bidireccional (a = 0,05). La adición de lámina de plomo no interfirió en la precisión diagnóstica de ambos sistemas digitales (p> 0,05) y no disminuyó el ruido en las imágenes (p> 0,05). Sin embargo, independientemente de la adición de la lámina de plomo, la placa de almacenamiento de fósforo presentó mayor ruido en comparación con el sensor (p?0,05). La adición de lámina de plomo al receptor digital no interfirió con el ruido de la imagen y con la precisión diagnóstica para detectar el instrumento endodóntico fracturado en condiciones ex vivo.

Abstract: Evaluating factors that may influence the nose dimensions and, therefore, contribute to the singularity of a person, is important for obtaining a precise facial reconstruction (FR) in forensic anthropology. Thus, the aim in this study was to evaluate the influence of sex, skeletal class, and facial type on nose dimensions of Brazilian individuals using cone-beam computed tomography (CBCT) scans. CBCT images of 54 males and 67 females were classified according to skeletal class (class I, II, or III) and facial type (brachycephalic, dolichocephalic and mesocephalic). Linear and angular measurements of the nose were performed using the CS 3D Imaging software. The measurements obtained for males and females were compared by one-way ANOVA. Two-way ANOVA was used to compare the measurements in the different skeletal classes and facial types. Significance level was set at 5%. All linear measurements were greater in males (p < 0.05); the angular measurements, however, did not differ between sexes (p > 0.05). Linear and angular measurements of class III males were significantly different from the other classes; the same was observed for the angular measurements in females (p < 0.05). Regarding facial types, some linear measurements were significantly greater in dolichocephalics males (p < 0.05). For females, there was no influence of facial type (p > 0.05), except for the nasal convexity angle. Nose dimensions differed in specific points among different skeletal classes and facial types, and there was sexual dimorphism in all linear nose dimensions. This information may be applicable for nose reconstructions, allowing more reliable FR.

ABSTRACT: Stafne bone defect (SBD) is a bone cavity in the lingual surface of the mandible normally filled by salivary gland tissue. In conventional radiographs, SBD typically resembles a radiolucent unilocular lesion with welldefined margins, localized under the inferior alveolar canal. The diagnosis of SBD is often incidental due to the asymptomatic nature. The aim of this study was to investigate the prevalence of SBDs in a Brazilian population and to describe the radiographic features of the cases reported. This retrospective study evaluated 17,180 digital panoramic radiographs of patients with an indication of radiography for dental treatment seen at three centers located in the three Brazilian states. In each center, two researchers evaluated the images for establishment of the consensual diagnosis of SBD. In the case of disagreement, a third researcher was consulted to reach a final consensus. To assess the prevalence of SBDs, sex and age of patients were considered, and SBDs were classified according to their form and location. Data were submitted to descriptive analysis. Among the 17.180 patients, only 15 (0.08 %) had SDB, including 3 women and 12 men. The age range of the patients with SDB was 30-69 years (mean: 49.2). Fourteen cases were located in the posterior region of the mandibular body and one case in the ascending ramus. Stafne bone defect is a rare developmental anomaly that more commonly affects middle-aged men. The condition has a typical radiographic appearance and panoramic radiography is a valuable tool for its diagnosis.

RESUMEN: El defecto óseo de Stafne (DOS) es una cavidad ósea en la superficie lingual de la mandíbula, normalmente llena de tejido glandular salival. En las radiografías convencionales, el DOS generalmente se asemeja a una lesión unilocular radiotransparente con bordes bien definidos, ubicada debajo del canal alveolar inferior. El diagnóstico de DOS a menudo es accidental debido a su naturaleza asintomática. El objetivo de este estudio fue investigar la prevalencia de DOS en una población brasileña y describir las características radiográficas de los casos reportados. Este estudio retrospectivo evaluó 17.180 radiografías panorámicas digitales de pacientes con indicación radiográfica para tratamiento dental atendidos en tres centros ubicados en tres estados brasileños. En cada centro, dos investigadores evaluaron las imágenes para establecer un diagnóstico consensuado de DOS. En caso de desacuerdo, se consultó a un tercer investigador para llegar a un consenso final. Para evaluar la prevalencia de DOS, se consideraron el sexo y la edad de los pacientes, y se clasificaron según su forma y ubicación. Los datos fueron sometidos a análisis descriptivo. Entre los 17.180 pacientes, solo 15 (0,08 %) tenían DOS, incluidos 3 mujeres y 12 hombres. El rango de edad de los pacientes con DOS fue de 30 a 69 años (media: 49,2). Catorce casos se ubicaron en la región posterior del cuerpo mandibular y un caso en la rama ascendente. Los defectos óseos de Stafne son una anomalía rara del desarrollo que afecta más comúnmente a los hombres de mediana edad. La condición tiene una apariencia radiográfica típica y la radiografía panorámica es una herramienta valiosa para su diagnóstico.

Abstract This study aims to assess the influence of high-density material on the radiographic diagnosis of proximal caries in digital systems with automatic exposure compensation, and to evaluate the effect of subjective adjustment of brightness and contrast to undertake this diagnostic task. Twenty bitewing radiographs of forty posterior human teeth with non-cavitated carious lesions, confirmed by micro-CT, were obtained with two digital systems. A porcelain-fused-to-metal crown attached to a titanium implant was inserted into the exposed area, and all the radiographs were repeated. Five radiologists assessed the radiographs and diagnosed proximal carious lesions. Afterwards, the observers were asked to adjust image brightness and contrast, based on their subjective perception, and to reassess the images. Thirty percent of each experimental group was reassessed to test intraobserver reproducibility, totaling 208 images per observer. Intraobserver and interobserver agreements ranged from fair to substantial. Sensitivity, specificity, predictive values, and area under the ROC curve were calculated and compared for each radiographic system, using ANOVA (α = 0.05). Overall, presence of high-density material and adjustment of brightness and contrast did not significantly influence the radiographic diagnosis of proximal caries (p ≥ 0.05). Regarding Digora Optime, adjustment of brightness and contrast significantly increased (p < 0.05) the diagnostic accuracy of proximal carious lesions in the presence of high-density material. In conclusion, the presence of high-density material in the X-rayed region does not influence radiographic diagnosis of proximal caries. However, when it is present in the X-rayed area, subjective adjustment of brightness and contrast is recommended for use with the Digora Optime digital system.

Resumo O propósito deste estudo foi testar o efeito radioprotetor do selênio na microarquitetura óssea de mandíbulas de ratos irradiados. Quarenta ratos foram separados em 4 grupos com 10 animais: grupo controle (GC), grupo irradiado (GI), grupo selenito de sódio (SSG) e grupo selenito de sódio irradiado (SSIG). Uma dose única de 0,8 mg/kg de selenito de sódio foi administrada intraperitonealmente nos grupos SSG e SSIG. Uma hora depois, os animais dos grupos IG e SSIG foram irradiados com 15 Gy de raios-x. Quarenta dias após a irradiação foi realizada extração bilateral dos primeiros molares inferiores. Após o procedimento de extração, cinco ratos foram mortos após quinze dias e outros cinco após trinta dias. A microtomografia computadorizada foi utilizada para avaliar o osso cortical e trabecular de cada rato. A média e o desvio padrão de cada parâmetro da microarquitetura óssea foi analisada pelo teste estatístico de Análise de Variância dois fatores (ANOVA), seguido por comparações post hoc com o teste de Tukey. Após 15 dias, o volume ósseo apresentou valores mais elevados nos grupos GC e GNS (p=0,001). Os mesmos grupos apresentaram valores estatisticamente significantes maiores quando se analisou fração de volume ósseo (p<0,001) e espessura trabecular (p<0,001). Após 30 dias, observou-se que, em relação à fração de volume ósseo, o grupo SSG apresentou o maior valor enquanto o grupo SSIG apresentou o menor valor, com diferença estatisticamente significante (p=0,016). O selenito de sódio demonstrou um efeito radioprotetor mediano na microarquitetura óssea das mandíbulas irradiadas, o que indica que a substância pode ser um potencial agente radioprotetor contra os efeitos crônicos da radioterapia.

Abstract The purpose of this study was to test the radioprotective effect of selenium in the bone microarchitecture of irradiated rats mandibles. Forty rats were separated into 4 groups with 10 animals: control group (CG), irradiated group (IG), sodium selenite group (SSG) and sodium selenite irradiated group (SSIG). A single dose of 0.8 mg/kg sodium selenite was administered intraperitoneally in the SSG and SSIG groups. One hour later, animals of IG and SSIG groups were irradiated with 15 Gy of x-rays. Forty days after radiation a bilateral extraction of the mandibular first molars was performed. After the extraction procedure, five rats were killed after fifteen days and others five after thirty days. Micro- computed tomography was used to evaluate cortical and trabecular bone of each rat. The mean and standard deviation of each bone microarchitecture parameter were analyzed using the statistical test of two-way Analysis of Variance (ANOVA). At 15 days, the bone volume presented higher values in the CG and SSG groups (p=0.001). The same groups presented statistically significant higher values when bone volume fraction (p<0.001) and trabecular thickness (p<0.001) were analyzed. At 30 days, it was observed that in relation to the bone volume fraction, SSG group presented the highest value while SSIG group had the lowest value, with statistically significant difference (p=0.016). Sodium selenite demonstrated a median radioprotective effect in the bone microarchitecture of irradiated mandibles, which indicates the substance may be a potential radioprotective agent against chronic effects of high doses of ionizing radiation.

Resumo A microtomografia computadorizada (microTC) é uma modalidade de imagem não destrutiva utilizada para avaliar a morfometria óssea. Para análise acurada, faz-se necessário segmentar o tecido ósseo do fundo (background) da imagem, evitando assim, sub ou sobre estimação do volume ósseo real. Desta forma, fica evidente que os métodos de segmentação em análise de microTC podem influenciar a precisão dos cálculos da morfometria óssea. A realização do presente estudo teve como objetivo comparar o desempenho de dois diferentes métodos de segmentação de imagem de microTC, subjetivo e objetivo, através da avaliação dos resultados das análises morfométricas obtidas de ossos humanos. Dezesseis amostras contendo parafusos de fixação cobertos por 0,5- 1 mm de osso humano foram escaneados usando o microtomógrafo SkyScan1173. Três examinadores realizaram a segmentação das imagens de forma subjetiva (visualmente) obtendo seus respectivos valores de threshold. Em seguida, a segmentação objetiva (automática) foi realizada. As análises tridimensionais foram obtidas utilizando os valores determinados por ambos os métodos no software CTAn. Cinco parâmetros morfométricos do osso foram calculados (BV / TV, Tb.Th, Tb.N, Tb.Sp, Conn.Den) e usados como variáveis dependentes. O teste ANOVA não mostrou diferenças estatisticamente significantes entre os métodos comparados: BV / TV (p=0,424), Tb.N (p=0,672), Tb.Th (p=0,183), Tb.Sp (p=0 973) e Conn.den (p=0,204). A concordância intra e interobservardores variou entre satisfatória e excelente (0,55-1 e 0,546-0,991, respectivamente). Portanto, os resultados obtidos com a segmentação subjetiva foram semelhantes aos obtidos com a automática. Entretanto, a segmentação automática dispensa intervenção humana, sendo um método verdadeiramente objetivo e deve ser a primeira escolha em estudos microTC que objetivam avaliar a morfometria óssea humana.

Abstract X-ray microtomography (microCT) is a nondestructive technique used to assess bone morphometry. For an accurate analysis, it is necessary to segment the bone tissue from the background images, avoiding under- or overestimation of the real bone volume. Thus, segmentation methods for microCT can influence the accuracy of bone morphometry analysis. The purpose of this study was to compare two different image segmentation methods available on microCT software (subjective and objective) regarding to the human bone morphometric analysis. Sixteen samples containing a fixation screws covered by 0.5-1mm of bone were scanned using the SkyScan 1173 scanner. Three examiners segmented the microCT images subjectively and recorded the threshold values. Subsequently, an objective segmentation was also done. The 3D analysis was performed for both images using the values previously determined in CTAn software. Five bone morphometric parameters were calculated (BV/TV, Tb.Th, Tb.N, Tb.Sp, Conn.Den) and used as dependent variables. ANOVA showed no significant differences between the methods concerning BV/TV (p=0.424), Tb.N (p=0.672), Tb.Th (p=0.183), Tb.Sp (p=0.973) and Conn.Den (p=0.204). Intra- and interobserver agreement ranged from satisfactory to excellent (0.55-1 and 0.546-0.991, respectively). Therefore, results obtained with subjective threshorlding were similar to those obtained with objective segmentation. Since objective segmentation does not have human input and it is a truly objective method, it should be the first choice in microCT studies that concern homogeneity and high resolution human bone sample.

Abstract To calculate root canal volume and surface area in microCT images, an image segmentation by selecting threshold values is required, which can be determined by visual or automatic methods. Visual determination is influenced by the operator's visual acuity, while the automatic method is done entirely by computer algorithms. Objective: To compare between visual and automatic segmentation, and to determine the influence of the operator's visual acuity on the reproducibility of root canal volume and area measurements. Material and methods: Images from 31 extracted human anterior teeth were scanned with a μCT scanner. Three experienced examiners performed visual image segmentation, and threshold values were recorded. Automatic segmentation was done using the “Automatic Threshold Tool” available in the dedicated software provided by the scanner's manufacturer. Volume and area measurements were performed using the threshold values determined both visually and automatically. Results: The paired Student's t-test showed no significant difference between visual and automatic segmentation methods regarding root canal volume measurements (p=0.93) and root canal surface (p=0.79). Conclusion: Although visual and automatic segmentation methods can be used to determine the threshold and calculate root canal volume and surface, the automatic method may be the most suitable for ensuring the reproducibility of threshold determination.

Resumo O objetivo deste estudo foi estimar a dose absorvida em exames de tomografia computorizada de feixe cônico (TCFC) de acordo com diferentes parâmetros de exposição, tamanho e posição do campo de visão (FOV, do inglês field of view). Além disso, comparou-se a dose absorvida em uma única aquisição com FOV grande com aquela em duas aquisições com FOVs menores para avaliação de estruturas bilaterais como a articulação temporomandibular (ATM). As aquisições de TCFC foram obtidas no aparelho OP300 Maxio, variando o modo de aquisição (standard, high e endo), bem como o tamanho (5x5, 6x8 e 8x15 cm) e o posicionamento do FOV. Com o FOV pequeno, foram escaneadas diferentes áreas (maxila ou mandíbula, anterior ou posterior e ATM). As doses absorvidas foram determinadas por meio da utilização de dosímetros termoluminescentes na superfície da pele em órgãos sensíveis de um phantom antropomórfico. O modo endo mostrou a dose mais alta, seguido pelos modos high e standard em todas as posições dos FOVs. Com um FOV pequeno, as doses foram maiores na região posterior, especialmente na mandíbula. A redução da dose ocorreu quando foram utilizados pequenos FOVs; contudo, essa redução não foi proporcional à redução do tamanho do FOV. Para a ATM, a dose em uma única aquisição com FOV grande foi maior que duas aquisições com FOV pequeno, porém inferior à dose de duas aquisições com FOV médio (6x8 cm). Em conclusão, o modo de aquisição, o tamanho e a posição do FOV têm grande influência na dose absorvida. FOVs pequenos apresentaram doses mais baixas em relação aos FOVs grandes, entretanto não há uma relação linear entre o tamanho do FOV e a dose absorvida. Para estruturas bilaterais como a ATM, a dupla aquisição com FOV pequeno representa uma diminuição na dose absorvida em relação a uma aquisição com FOV grande.

Abstract This study aimed to estimate the absorbed dose in cone beam computed tomography (CBCT) exams according to different exposure parameters and size and position of the field of view (FOV). In addition was compared the absorbed dose of two smaller FOV scans with that of a larger FOV scan for evaluation of temporomandibular joint (TMJ), as it is a bilateral structure. CBCT scans were obtained on OP300 Maxio unit varying scanning mode (standard, high and endo) as well as size (5x5, 6x8 and 8x15 cm) and positioning of FOV. With a small FOV, different areas were scanned (maxilla or mandible, anterior or posterior and TMJ). Absorbed doses were determined using thermoluminescent dosimeters on the skin surface of sensitive organs of an anthropomorphic phantom. Endo mode showed the highest dose, followed by the high and standard modes in all FOV positions. With small FOV, doses were higher in the posterior region, especially in the mandible. Dose reduction occurred when small FOVs were used, but it was not proportional to FOV size reduction. For TMJ, the dose in a single acquisition with large FOV was greater than two acquisitions with small FOV, but lower than two acquisitions with medium FOV (6x8 cm). In conclusion, scanning mode, size and FOV position have great influence on the absorbed dose. Small FOV decreases the dose, but there is no linear relation between FOV size and dose. For bilateral exams of TMJ, double acquisition with small FOVs produces decrease in absorbed dose relative to a large FOV.