The effect of voxel and field of view size on the volumetric alteration artifact of high-density materials with 2 cone beam computed tomography devices.

OBJECTIVE: We investigated the influence of voxel and field of view (FOV) sizes on expression of the volumetric alteration artifact (VAA) of 5 high-density materials in 2 cone beam computed tomography (CBCT) devices. STUDY DESIGN: Cylinders of amalgam, cobalt-chromium, gutta-percha, titanium, and zirconium were individually positioned in a polymethyl methacrylate phantom. OP300 Maxio and ProMax 3D Classic CBCT devices were used to acquire images with varying voxel and FOV sizes, totaling 585 scans. Two evaluators segmented the high-density cylinder images to obtain the tomographic volumes. The difference between the tomographic and physical volume of each cylinder (i.e., volumetric alteration) was calculated. Statistical analysis was conducted with multiway ANOVA and the Tukey post hoc test (α = 5%). Evaluator reliability was measured with the intraclass correlation coefficient (ICC). RESULTS: All studied parameters and nearly all interactions influenced the VAA (P < .05). The post hoc test demonstrated less volumetric alteration for the smallest voxel sizes, 61 × 78 mm FOV, and gutta-percha for OP300, and for the smallest voxel sizes, 80 × 80 mm FOV, and gutta-percha and titanium for ProMax 3D (P < .05). The ICC demonstrated perfect reliability (1.00). CONCLUSIONS: Voxel and FOV sizes influenced VAA expression. Using smaller voxel sizes, the 61 × 78 mm FOV for OP300 and the 80 × 80 mm FOV for ProMax 3D, and materials with lower density and lower atomic number reduced VAA expression.

Convex triangular vs. cylindrical field of view: how does the shape of the FOV affect radiation dose?

OBJECTIVE: To compare the dosimetry between convex triangular fields of view (FOV) and similar dimension cylindrical FOVs of two cone-beam computed tomography (CBCT) models. METHODS: Optically stimulated luminescence dosimeters (OSLDs) were placed in fiducial anatomical locations in an anthropomorphic phantom representing an adult head male for dosimetry scans. Convex triangular FOVs (100 × 80 mm/maxilla-mandible; 100 × 50 mm mandible; 100 × 50 mm/maxilla) from Veraviewepocs 3D R100 (J. Morita, Kyoto, Japan) (R100) and Veraview® X800 (J. Morita, Kyoto, Japan) (X800) and cylindrical FOVs from R100 and X800 (80 × 80 mm/maxilla-mandible; 80 × 50 mm/mandible; 80 × 50 mm/maxilla) were obtained, resulting in 12 different scan protocols. Equivalent doses for each relevant organ/tissue and the effective dose for each protocol were calculated. Mean effective doses were compared by the two-way analysis of variance (ANOVA) with Tukey's post hoc test to evaluate the effect of the FOV and device (α = 0.05). RESULTS: The effective doses ranged between 69 and 324 µSv for the convex triangular FOVs and 76 and 332 µSv for the cylindrical FOVs. Convex triangular FOVs from the R100 device had effective doses 2.3 to 15.3% lower than their corresponding cylindrical FOVs with similar height (p < 0.05), and that difference ranged between 8.8 and 11.8% for the X800 device (p < 0.05). CONCLUSION: Convex triangular fields of view delivered slightly lower effective doses than the cylindrical fields of view of similar dimensions in the R100 and X800 CBCT devices. CLINICAL RELEVANCE: Understanding the influence of the image geometry formation in effective dose allows optimization to reduce patient dose.

DICOM file format has better radiographic image quality than other file formats: an objective study

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.

Monitoring cone-beam CT radiation dose levels in a University Hospital.

OBJECTIVE: To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age. METHODS: An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes. RESULTS: A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction. CONCLUSIONS: Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

Could the radiographic image quality be affected by the excessive use of the photostimulable phosphor plate?

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.

Influence of extensive use of a photostimulable phosphor receptor on the diagnosis of proximal carious lesions: An in vitro study.

OBJECTIVE: The aim of this study was to evaluate the influence of the extensive use of a photostimulable phosphor (PSP) receptor on the diagnosis of proximal carious lesions. STUDY DESIGN: Forty posterior teeth were paired and mounted in 20 phantoms. Using a PSP receptor of the Express intraoral system, 1 radiograph of each phantom was acquired, totaling 20 radiographs (group 1). After 400 acquisitions, another radiograph of each phantom was obtained, totaling 20 new radiographs (group 2). This procedure was also done after 800 (group 3), 1,200 (group 4), and 1,600 (group 5) acquisitions, resulting in 100 radiographs. Another 40 radiographs (20 phantoms × 2 groups) were obtained with a second PSP sensor to evaluate the diagnostic replicability of the receptors. All 140 radiographs were assessed independently by 5 examiners for the presence of proximal caries. Area under the receiver operating characteristic curve, sensitivity, and specificity were calculated and compared among the groups by analysis of variance. The Student t test evaluated the diagnostic replicability of the receptors. The significance level was set at 5% (P < .05). RESULTS: The diagnostic outcomes for proximal caries did not differ among the groups (P ≥ .37). The diagnostic values did not differ among the radiographs acquired with the 2 PSP receptors (P ≥ .75). CONCLUSIONS: The diagnosis of proximal carious lesions was not affected by extensive use of the PSP receptor.

Human Identification by Comparative Analysis of Frontal Sinuses: Study on Computed Tomography

ABSTRACT: Generally, primary methods of identification as the fingerprint analysis, dental analysis or DNA examination are indicated for the establishment of the identity of a corpse. In situations with poor body conservation, such as in advanced stage of putrefaction or skeletonization, imaging exams like medical and dental computed tomography can assist in the process of identification. The frontal sinuses present anatomical characteristics that allow the establishment of the identity of an in dividual. In this case report we used the technique of three-dimensional construction of the frontal sinuses through the generation of solid figures representative of the sinus morphology. After the comparative analysis of the antemortem and postmortem tomography of the alleged victim, we could establish similarities in both the variations in size, shape, symmetry and contour of borders, and the presence and number of septa, allowing us to infer that the two images described belong to the same individual, thus establishing the identity of the corpse found.

RESUMEN: Generalmente, los métodos primarios de identificación como el análisis dactiloscópico, el análisis dental o el examen de ADN están indicados para el establecimiento de la identidad de un cadáver. En situaciones de mala conservación del cuerpo, como en etapa avanzada de putrefacción o esqueletización, los exámenes de imagen como la tomografía computarizada médica y dental pueden ayudar en el proceso de identificación. Los senos frontales presentan características anatómicas que permiten establecer la identidad de un individuo. En este reporte de caso utilizamos la técnica de construcción tridimensional de los senos frontales a través de la generación de figuras sólidas representativas de la morfología sinusal. Tras el análisis comparativo de la tomografía antemortem y postmortem de la presunta víctima, pudimos establecer similitudes tanto en las variaciones de tamaño, forma, simetría y contorno de márgenes, como en la presencia y número de septos, lo que nos permite inferir que las dos imágenes descritas pertenecen al mismo individuo, estableciéndose así la identidad del cadáver encontrado.

Interexaminer agreement between two dental specialties for the detection of bifid mandibular canal and accessory mental foramen in cone-beam computed tomography / Concordancia inter-examinador entre dos especialidades odontológicas para la detección del canal mandibular bífido y foramen mental accesorio en tomografía computarizada de haz cónico

Introduction: The aim of this study was to assess the agreement between oral and maxillofacial radiologists (OMFR) and oral and maxillofacial surgeons (OMFS) for the detection of bifid mandibular canal (BMC) and accessory mental foramen (AMF) using cone-beam computed tomography (CBCT). Material and Methods: This retrospective study involved 22 examiners (11 OMFR and 11 OMFS) who independently assessed 30 CBCT volumes from patients (n = 60 hemi-mandibles) under preoperative radiographic evaluation for implant placement. The examiners scored the presence of BMC and AMF in each hemimandible. The interexaminer agreements were assessed using Fleiss' kappa statistics. Results: For intra-examiner agreement, 40% of the sample was reevaluated. The interexaminer agreement between OMFR and OMFS was slight (0.12) for the detection of BMC and fair (0.24) for AMF. The agreement among OMFR for detection of BMC was fair (0.22), and it was slight among OMFS (0.15). The agreement among OMFR for detection of AMF was substantial (0.61), and among OMFS it was fair (0.22). Agreements between OMFR and OMFS were slight for BMC and fair for AMF, independently of the years of experience. Intraexaminer agreement ranged from 60% to 90% among OMFR and from 55% to 90% among OMFS. Conclusion: A slight and a fair agreement between OMFR and OMFS was found for the detection of BMC and AMF, respectively. In general, OMFR obtained higher agreement among themselves, mainly for detection of AMF.

Introducción: El objetivo de este estudio fue evaluar la con-cordancia entre los radiólogos orales y maxilofaciales (ROMF) y los cirujanos orales y maxilofaciales (COMF) para la detección del canal mandibular bífido (CMB) y el foramen mentoniano accesorio (FMA) mediante tomografía computarizada de haz cónico. CBCT). Material y Métodos: Este estudio retrospectivo involucró a 22 examinadores (11 ROMF y 11 COMF) que evaluaron de forma independiente 30 volúmenes CBCT de pacientes (n = 60 hemimandíbulas) bajo evaluación radiográfica preoperatoria para la colocación de implantes. Los examinadores puntu-aron la presencia de CMB y FMA en cada hemimandíbula. Los acuerdos entre examinadores se evaluaron utilizando las estadísticas kappa de Fleiss. Resultados: Por concordancia intraexaminador se reeva-luó el 40% de la muestra. El acuerdo entre examinadores entre ROMF y COMF fue ligero (0,12) para la detección de CMB y regular (0,24) para FMA. La concordancia entre ROMF para la detección de CMB fue regular (0,22) y leve entre COMF (0,15). El acuerdo entre ROMF para la detección de FMA fue sustancial (0,61), y entre COMF fue justo (0,22). Los acuerdos entre ROMF y COMF fueron leves para CMB y justos para FMA, independientemente de los años de experiencia. La concordancia entre examinadores varió del 60 % al 90 % entre ROMF y del 55 % al 90 % entre COMF. Conclusión: Se encontró un acuerdo leve y justo entre ROMF y COMF para la detección de CMB y FMA, respec-tivamente. En general, se obtuvo mayor acuerdo entre ROMF, principalmente para la detección de FMA.

Evaluation of the microstructure, chemical composition, and image quality of different PSP receptors

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.

Artificial intelligence for detection of periapical lesions on intraoral radiographs: Comparison between convolutional neural networks and human observers.

OBJECTIVE: The aim of this study was to compare the diagnostic performance of convolutional neural networks (CNNs) with the performance of human observers for the detection of simulated periapical lesions on periapical radiographs. STUDY DESIGN: Ten sockets were prepared in bovine ribs. Periapical defects of 3 sizes were sequentially created. Periapical radiographs were acquired of each socket with no lesion and with each lesion size with a photostimulable storage phosphor system. Radiographs were evaluated with no filter and with 6 image filter settings. A CNN architecture was set up using Keras-TensorFlow. Separate CNNs were evaluated for randomly sampled training/validation data and for data split up by socket (5-fold cross-validation) and filter (7-fold cross-validation). CNN performance on validation data was compared with that of 3 oral radiologists for sensitivity, specificity, and area under the receiver operating characteristic curve (ROC-AUC). RESULTS: Using random sampling, the CNN showed perfect accuracy for the validation data. When data were split up by socket, the mean sensitivity, specificity, and ROC-AUC values were 0.79, 0.88, and 0.86, respectively; when split up by filter, they were 0.87, 0.98, and 0.93, respectively. For radiologists, the values were 0.58, 0.83, and 0.75, respectively. CONCLUSIONS: CNNs show promise in periapical lesion detection. The pretrained CNN model yielded in this study can be used for further training on larger samples and/or clinical radiographs.

Influence of voxel size on cone beam computed tomography artifacts arising from the exomass.

OBJECTIVES: The objective of this study was to evaluate the influence of voxel size on artifacts arising from the exomass in cone beam computed tomography (CBCT). STUDY DESIGN: An imaging phantom was scanned using 2 CBCT units, each adjusted to 2 voxel sizes: 0.2 and 0.3 mm. From 1 to 3 metal inserts of titanium, cobalt-chromium, or amalgam were placed in the exomass and additional CBCT scans were acquired. Mean voxel gray values were obtained from 16 homogeneous areas of the phantom and averaged, and the standard deviation was calculated to obtain voxel gray value variability. The data were analyzed using 2-way analysis of variance, Tukey, and Dunnett tests (α =.05). RESULTS: Overall, mean voxel gray values and voxel gray value variability did not differ significantly between CBCT scans obtained with voxel sizes of 0.2 and 0.3 mm for either CBCT model tested (P > .05). Despite some exceptions in which significant differences were observed between the 2 voxel sizes (P < .05), the mean voxel gray values and voxel gray value variability resulting from different metal compositions and, in most situations, for different numbers of metal inserts in the exomass were not affected. CONCLUSION: Voxel size has little influence on exomass-related CBCT artifacts.

Influence of the file format and transmission app on the radiographic diagnosis of caries lesions.

OBJECTIVES: This in vitro study aimed to evaluate the influence of the radiographic image file format and the transmission application (app) on the diagnosis of proximal caries lesions. STUDY DESIGN: Twenty bitewing radiographs of 40 posterior human teeth placed in phantoms were acquired using the Digora Toto digital sensor. All images were exported as TIFF (Tagged Image File Format), BMP (Windows Bitmap), PNG (Portable Network Graphics), and JPEG (Joint Photographic Experts Group) and transmitted online via WhatsApp and Messenger. Five examiners evaluated the radiographs with no online transmission and as transmitted through the 2 apps for the presence of proximal caries lesions using a 5-point scale. The reference standard for caries lesions was established using micro-computed tomography. Two-way analysis of variance compared values of sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (α = .05). The kappa test was used to assess intra- and interexaminer agreement. RESULTS: Sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve values showed no significant differences in the diagnosis of proximal caries lesions between the different image file formats (P ≥ .773) and transmission apps (P ≥ .608). Intraexaminer agreement was substantial (κ = 0.742) and interexaminer agreement was moderate (κ = 0.475). CONCLUSION: The digital file format and transmission app did not influence the radiographic diagnosis of proximal caries lesions.

Development and validation of two new image receptor-holding devices for overlapping reduction of proximal surfaces in bitewing radiography: a preclinical study.

OBJECTIVE: To create and validate two new Image Receptor-Holding devices (IRHDs) to reduce proximal surfaces overlapping in bitewing radiography in comparison to a regular well-established and commercially available IRHD. METHODS: Two IRHDs for bitewing radiographs with a wedge on the biting surface were designed and 3D-printed. These IRHDs, with a large wedge (Pr-Lw) and small wedge (Pr-Sw), were compared with a regular commercially available IRHD (Rinn XCP®) during image acquisition of bitewing radiographs of four posterior regions (one upper region and three lower regions) in two dry skulls and mandibles. A total of 156 interproximal regions on bitewing radiographs were radiographed by 13 oral radiology graduate students and independently assessed by two oral radiologists (10 years of experience). IRHDs were compared by Cochran's Q test regarding the number of overlapped proximal surfaces in the acquired radiographs with a significance level of 5%. RESULTS: The observers were in perfect agreement (κ = 1.0) to classify the proximal surfaces overlapping. The Pr-Lw IRHD presented the lowest number of surfaces overlapping (19.2%) followed by the Pr-Sw IRHD (48.1%) and the XCP®IRHD with the highest surfaces overlapping (71.2%). The Pr-Lw IRHD surfaces overlapping was statistically different from the XCP IRHD (p < 0.001), and the Pr-Sw IRHD (p = 0.014). CONCLUSIONS: The Pr-Lw IRHD demonstrated the most efficient performance in overlapping surfaces reduction, compared with the Pr-Sw IRHD and the XCP® IRHD in adult dry skulls and mandibles.

Oral and Maxillofacial Radiology During the Coronavirus Disease 2019 Pandemic: Recommendations for a Safer Practice / Radiología oral y maxillofacial durante la pandemia por Coronavirus 2019: recomendaciones para una práctica más segura

Abstract The Coronavirus 2019 disease (COVID-19), was declared a pandemic by the World Health Organization on March 11, 2020, and registered the first case in Costa Rica on March 6, 2020, and 105 days later reported 2058 cases, with a wide age range (0-92 years). Its etiologic agent is the beta coronavirus SARS-CoV-2 with confirmed human- to-human transmission, mainly by the respiratory route. The presence of asymptomatic carriers of the virus and its transmission even without the manifestation of symptoms challenges health professionals worldwide. For this reason, assuming all patients who need dental care as possible carriers of the SARS-CoV-2 is mandatory and consequently, applying biosecurity measures with strict criteria. In the present literature review, we aim to recommend biosecurity measures to be applied during imaging examinations of dental patients due to the Coronavirus-2019 pandemic. We found that in the absence of treatment for COVID-19 disease and because of its high transmissibility, the most effective measures to prevent its spread are those allowing its containment. Therefore, the authors recommend: 1) acquiring imaging exams just in case of dental urgencies or emergencies, 2) prioritizing the use of extraoral exams, such as panoramic radiography or CBCT, under the principle of ALADAI and 3) the intraoral exams should be used just in case of a lack of extraoral imaging devices, or because of the need to solve diagnostic tasks in which they have a superior diagnostic value than those of the extraoral examinations.

Resumen La enfermedad Coronavirus 2019, fue declarada pandemia por la Organización Mundial de la Salud el 11 de marzo de 2020; el primer caso registrado en Costa Rica fue el 6 de marzo de 2020, y 105 días después reportó 2058 casos, con un amplio rango de edad (0-92 años). Su agente etiológico es el beta coronavirus SARS- CoV-2. La transmisión de humano a humano está bien confirmada principalmente por la vía respiratoria. La presencia de portadores asintomáticos del virus y su transmisión, incluso sin la manifestación de síntomas, desafía a los profesionales de la salud. Por esta razón, es obligatorio asumir todos los pacientes que necesitan atención dental como posibles portadores del SARS-CoV-2 y, en consecuencia, aplicar medidas de bioseguridad con criterios estrictos. En la presente revisión de la literatura, nuestro objetivo es recomendar las medidas de bioseguridad que se aplicarán durante los exámenes de imágenes de pacientes dentales debido a la pandemia de Coronavirus-2019. Encontramos que en ausencia de tratamiento para la enfermedad de COVID-19 y debido a su alta transmisibilidad, las medidas más efectivas para prevenir su propagación son aquellas que permitan su contención. Por lo tanto, se recomienda: 1) adquirir exámenes por imágenes solo en caso de urgencias o emergencias dentales, 2) priorizar el uso de exámenes extraorales, como la radiografía panorámica o CBCT, bajo el principio de ALADAIP y 3) se deben usar los exámenes intraorales solo en caso de falta de dispositivos de imágenes extraorales, o por la necesidad de resolver tareas de diagnóstico en las que tienen un valor de diagnóstico superior al de los exámenes extraorales.

Effect of resveratrol on the progression of experimental periodontitis in an ovariectomized rat model of osteoporosis: Morphometric, immune-enzymatic, and gene expression analysis.

OBJECTIVE: This study aimed to determine the role of resveratrol (RESV) on the progression of experimental periodontitis (EP) in ovariectomy rats (OVT). BACKGROUND: Estrogen deficiency is the main cause of osteoporosis and is related to higher periodontal attachment loss and reduction of alveolar bone. Zoledronate (ZLD) is an antiresorptive drug used to control osteoporosis but can lead to osteonecrosis of the jaw. RESV, a natural product, can reduce bone loss and control and prevent osteoporosis. Thus, this study aimed at investigating the effect of RESV on the progression of EP in estrogen-deficient rats. MATERIAL AND METHODS: The animals were subjected to the OVT or sham surgery to induce estrogen-deficiency and then were divided into the groups: OVT + RESV (n: 10); OVT + PLAC (n: 10): OVT + placebo; OVT + ZLD +PLA (n: 10); OVT + RESV +ZLD (n: 10): OVT + RESV and ZLD; SHAM (n: 10): non-ovariectomized animals + placebo. To induce estrogen deficiency, the rats were subjected to ovariectomy. Experimental periodontitis was induced by the placement of a ligature at the second maxillary molars. Daily administration of the placebo solution, resveratrol (10 mg/kg), and ZLD (0.1 mg/kg) was carried out for a period 42 days prior to initiation of EP, and then for another 28 days following ligature placement. After euthanasia, the specimens were processed for micro-CT and morphometric analysis of bone loss (linear measurement), and the gingival tissue surrounding the maxillary second molar was collected for the quantification of inflammatory markers using Luminex/MAGPix, of oxidative stress markers using ELISA assay, and gene expression analysis of bone markers, by real-time PCR. RESULTS: Morphometric and micro-CT analysis showed higher bone loss and lower bone density, respectively, in OVT + PLAC when compared to the other groups (P < .05). ZLD treated groups had lower alveolar bone loss, as well as, higher density and percentage of bone volume, when compared to OVT + RESV and SHAM + PLAC groups (P < .05). IL-4 levels were significantly lower in the OVT + PLAC group versus OVT + ZLD +RESV and SHAM + PLAC (P < .05). NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) levels were significantly lower OVT + RESV group when compared to OVT + PLAC (P < .05). OPG mRNA levels were lower in OVT + PLAC compared with the SHAM + PLAC group (P < .05). CONCLUSION: It can be concluded that resveratrol modulated alveolar bone loss during experimental periodontitis progression in estrogen-deficient rats by downregulating NADPH oxidase levels.

A quantitative analysis of metal artifact reduction algorithm performance in volume correction with 3 CBCT devices.

OBJECTIVE: The aim of this study was to quantitatively assess the performance of metal artifact reduction (MAR) algorithms on the volume of metal cylinders, considering the influence of materials, positions, and fields of view (FOVs), by using 3 cone beam computed tomography (CBCT) devices (NewTom VGi evo, Picasso Trio, and ProMax 3-D Max). STUDY DESIGN: Nine phantoms containing cylinders of amalgam, copper-aluminum (CuAl) metal alloy, and titanium, combined in up to 3 positions, were scanned by using 2 different FOVs. MATLAB software was used to evaluate the differences between volumes before and after MAR application, and the possible interference of materials, positions, and FOVs. Wilcoxon's test and the Kruskal-Wallis test were used at a level of significance of 5%. RESULTS: In general, images containing amalgam and CuAl showed a significant difference in volume before and after MAR application. However, no significant difference after MAR was observed (P > .05) relative to positions and FOVs. MAR had an impact on the cylinder volumes only in the NewTom VGi evo and ProMax 3-D Max scanners. CONCLUSIONS: The performance of MAR algorithms in volume correction of metal objects is dependent on the materials and the CBCT unit.

Distribution of metal artifacts arising from the exomass in small field-of-view cone beam computed tomography scans.

OBJECTIVES: To evaluate the distribution of metal artifacts from the exomass in small field-of-view (FOV) cone beam computed tomography (CBCT) scans. STUDY DESIGN: An image phantom was scanned by using 3 CBCT units. Metal objects were positioned in the exomass, and additional CBCT scans were obtained. Mean gray values were obtained from 16 homogeneous areas and the standard deviation was calculated to quantify gray level inhomogeneity according to distinct zones of the FOV: total area and outer, inner, right, left, and mid-zones. The discrepancy between each zone and the total area was calculated to compare different CBCT units. Mean gray, gray level inhomogeneity, and discrepancy values were separately assessed by using analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: Overall, the mean gray values were significantly lower in the inner zone, and the gray level inhomogeneity values were significantly higher in the inner and mid-zones irrespective of the presence of metal objects in the exomass. The 3 CBCT units presented significantly different discrepancy values in most conditions. CONCLUSIONS: The distribution of metal artifacts from the exomass follows the inherent gray value dispersion of CBCT images, with greater inhomogeneity in the inner zone of the FOV. This is exacerbated when metal objects are in the exomass.

Effect of homeopathy in the function and morphology of salivary parotid glands of irradiated rats / Efeito da homeopatia na função e morfologia das glândulas parótidas de ratos irradiados

Objective: To evaluate the radioprotective effect of a homeopathic solution in salivary function and parotid glands morphology of irradiated rats. Materials and Methods: The sample consisted of 150 rats randomly divided into 6 groups. The groups were named based on the substance administered: Control- saline solution; Irradiated Control- saline solution and 15 Gy of X radiation; Alcohol-hydroalcoholic solution dynamized at 15 CH; Irradiated Alcohol- hydroalcoholic solution dynamized at 15 CH and 15 Gy of X radiation; Homeopathy- 0.25 ml (1mL/kg) of the irradiated hydroalcoholic solution and dynamized at 15 CH; Irradiated homeopathy- homeopathic solution and 15 Gy of X radiation. Each group was subdivided into 5 different subgroups, based on the time point of euthanasia: 12 hours, 3, 10, 17, and 24 days. The medication was administered for 7 days before and 7 days after the radiation treatment. On the day of euthanasia, salivation was induced with pilocarpine and collected. The animals were then sacrificed and the parotid glands were removed. Results: Salivary function analysis showed that only group irradiated homeopathy euthanized on day 17 had a statistically significant difference when compared to other irradiated groups, presenting a higher salivation flow rate. The only group that showed a statistically significant difference in the number of acini over time was the irradiated alcohol group, which presented a tendency of reduction. Conclusion: The homeopathic solution presented a late radioprotective effect based on salivary function and morphological analysis of the parotid gland.

Objetivo: Avaliar o efeito radioprotetor de uma solução homeopática na função salivar e na morfologia das glândulas parótidas de ratos irradiados. Materiais e Métodos: A amostra foi composta por 150 ratos divididos aleatoriamente em 6 grupos. Os grupos foram nomeados com base na substância administrada: solução salina controle; Solução salina controle irradiada e 15 Gy de radiação X; Solução álcool-hidroalcoólica dinamizada a 15 CH; Solução hidroalcoólica de álcool irradiado dinamizada a 15 CH e 15 Gy de radiação X; Homeopatia - 0,25 ml (1mL / kg) da solução hidroalcoólica irradiada e dinamizada a 15 CH; Homeopatia irradiada - solução homeopática e 15 Gy de radiação X. Cada grupo foi subdividido em 5 subgrupos diferentes, com base no tempo da eutanásia: 12 horas, 3, 10, 17 e 24 dias. O medicamento foi administrado por 7 dias antes e 7 dias após o tratamento com radiação. No dia da eutanásia, a salivação foi induzida com pilocarpina e coletada. Os animais foram então sacrificados e as glândulas parótidas foram removidas. Resultados: A análise da função salivar mostrou que apenas a homeopatia irradiada por grupo sacrificada no dia 17 apresentou diferença estatisticamente significante quando comparada a outros grupos irradiados, apresentando maior taxa de fluxo de salivação. O único grupo que apresentou diferença estatisticamente significante no número de ácinos ao longo do tempo foi o grupo álcool irradiado, o qual apontou uma tendência de redução. Conclusão: A solução homeopática apresentou efeito radioprotetor tardio baseado na função salivar e na análise morfológica da glândula parótida.

Is the digital radiographic detection of approximal caries lesions influenced by viewing conditions?

OBJECTIVES: The aim of this study was to assess the influence of different viewing conditions (combinations of computer display, horizontal viewing angle, and ambient lighting) on the detection of approximal caries lesions on digital radiographic images. STUDY DESIGN: Forty posterior teeth were mounted in a plaster block and radiographed by using a CMOS sensor-based system. Three oral radiologists assessed the radiographic images under different conditions of computer display (iMac 5K 27", Barco MDRC-2124, and Dell P2314H), horizontal viewing angles (90 degrees, 67.5 degrees, and 45 degrees), and ambient lighting (low, medium, and high) and were asked to detect the presence of approximal caries lesions, which were confirmed by means of micro-computed tomography (micro-CT), using a 5-point scale. The area under the receiver operating characteristic curve, sensitivity, and specificity were calculated and compared by analysis of variance testing (α = 0.05). Intra- and interobserver agreements were assessed with the Kappa test. RESULTS: Computer display, horizontal viewing angle, and ambient lighting did not significantly influence the diagnosis of approximal caries lesions. In general, moderate values of accuracy, low sensitivity, and high specificity were found for all viewing conditions. CONCLUSIONS: The viewing conditions assessed in this study did not influence the detection of approximal caries lesions on digital radiographic images. Dental practitioners are encouraged to find their most comfortable viewing condition for this diagnostic task.

Automatic exposure compensation and subjective image enhancement in the radiographic diagnosis of caries

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.