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RESUMEN Introducción: Universalmente se acepta que la radiografía postero-anterior de cráneo presenta menor grado de distorsión que otras imágenes radiográficas, por lo que las mediciones en ella son consideradas confiables. Objetivo: Determinar el porcentaje de distorsión que se presenta en las diferentes regiones faciales de la radiografía posteroanterior de cráneo. Métodos: Treinta cráneos humanos con sus mandíbulas fueron divididos por tres planos horizontales y cuatro verticales en quince cuadrantes; resultaron diez en el cráneo y cinco en la mandíbula. En cada uno de ellos se colocó un alambre de acero en posiciones vertical y horizontal y se midió su longitud (medida real). A cada conjunto se le tomó una radiografía en proyección postero-anterior y se midió la longitud de los alambres en la imagen (medida radiográfica). Resultados: No fue posible medir en los cuadrantes laterales del cráneo. La medida horizontal en los cuadrantes intermedios inferiores derecho e izquierdo del cráneo y en los cuadrantes intermedio y lateral de ambos lados de la mandíbula no es confiable; en el cuadrante mediano de la mandíbula se minimiza; en los cuadrantes medianos superior e inferior e intermedios superiores derecho e izquierdo del cráneo se magnifica. Las medidas verticales en todos los cuadrantes son confiables; en los cuadrantes intermedios superiores derecho e izquierdo del cráneo y en los intermedios y laterales derechos e izquierdos de la mandíbula se magnifica; en los cuadrantes intermedios inferiores y medianos superior e inferior del cráneo y mediano de la mandíbula se minimiza. La menor distorsión para ambas medidas se presenta en el cuadrante mediano superior del cráneo. Se reportan los porcentajes de distorsión para cada cuadrante. Conclusiones: Se presenta distorsión en la radiografía postero-anterior de cráneo y esta varía de una región a otra de la cara(AU)

ABSTRACT Introduction: Universally, it has been accepted that the postero-anterior cephalogram presents less distortion than any other x-ray radiograph; for this reason, the measurements taken on it are considered reliable. Objective: To determine for a postero-anterior cephalogram, what percentage of distortion is present in different regions of the skull and mandible. Methods: Thirty human skulls with their mandibles were divided by three horizontal and four vertical planes in fifteen quadrants, resulting ten in the skull and five in the mandible. In each quadrant, one vertical and one horizontal steel wire were fixed and their lengths were measured (real value). To each set, a postero-anterior cephalogram was taken and the wire images were measured (radiograph value). Results: No measurement could be taken in the lateral quadrants of the skull. The horizontal measurement in the right and left intermediate inferior quadrants of the skull and in the right and left intermediate and lateral quadrants of the mandible is not reliable; in the median quadrant of the mandible it is minimized; in the median superior and inferior and intermediate superior right and left quadrants of the skull it is magnified. The vertical measurement in all the quadrants is reliable; in the right and left intermediate superior quadrants of the skull and right and left intermediate and lateral quadrants of the mandible it is magnified; in the right and left intermediate inferior and median superior and inferior quadrants of the skull and median quadrant of the mandible it is minimized. The minimum distortion for both measurements is present in the median superior quadrant of the skull. The percentage of distortion in each quadrant for both measurements is reported. Conclusions: Distortion is present in the postero-anterior cephalogram and it varies from one region to another of the face(AU)

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Dental X-rays are widely used in clinical practice, since the technique is an important approach for diagnosing diseases in dental and periodontal tissues. However, it is widely known that radiation is capable of causing damage to cellular systems, such as genotoxicity or cytotoxicity. Thus, the aim of this review was to present a critical analysis regarding the studies published on genotoxicity and cytotoxicity induced by dental X-rays in oral mucosa cells. Such studies have revealed that some oral cell types are more sensitive than others following exposure to dental X-rays. Certainly, this review will contribute to a better understanding of this matter as well as to highlighting perspectives for further studies. Ultimately, such data will promote better safety for both patients and dental professionals.

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En odontología, para la obtención de imágenes radiográficas intraorales por métodos convencionales, se utilizan paquetes radiográficos que contienen en su interior a la película radiográfica. Luego de la exposición del paquete radiográfico a los rayos X se realiza el procesado, lo cual requiere el uso de líquidos reveladores y fijadores, que son las sustancias químicas que harán posible la visualización de la imagen.Tanto el paquete radiográfico como lo líquidos de procesado presentan en su constitución elementos que, por sus características, pueden ser incluidos enel rubro de “elementos peligrosos” para la salud y para el medio ambiente. En este trabajo de divulgación se pretende realizar un análisis de las características que hacen a la peligrosidad de cada uno de los componentes del paquete radiográfico y de los líquidos —revelador y fijador— usados en el procesado, lo cual es necesario conocer para el manejo seguro y adecuado de este tipo de elementos...

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OBJECTIVES: To evaluate and compare mutagenicity (micronucleus) and cytotoxicity (karyorrhexis, pyknosis, and karyolysis) in exfoliated buccal mucosa cells of children following cone beam computed tomography (CBCT) or conventional radiograph exposure necessary for orthodontic planning. MATERIALS AND METHODS: A total of 49 healthy children were submitted to CBCT or a conventional orthodontic radiographic protocol; they were divided into two groups based on exam: CBCT (n  =  24) and Radiographic Set (n  =  25) groups. The micronucleus test in the exfoliated buccal mucosa cells was applied. RESULTS: There was not a statistically significant difference (P > .05) found between the number of micronucleated buccal mucosa cells (MNC) before and after exposure to radiation in either group, showing that neither group experienced a mutagenic effect. However, radiation did cause other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis, and karyolysis, in both groups (P < .05). The CBCT group presented a greater increase in cell death than was noted in the Radiographic Set group (P < .044). CONCLUSION: According to the micronucleus test, mutagenicity was not induced by the CBCT or the conventional radiographs, but cytotoxicity was verified after these exams, especially after CBCT. That might have happened once the CBCT group received a greater radiation dose than the Radiographic Set group as a result of the protocols used in orthodontic planning for this study.

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OBJECTIVES: In the past decades, X-rays have been used widely for diagnosis in dentistry. However, it is well known that ionizing radiation causes damage (including single- and double-strand breaks) to deoxyribonucleic acid (DNA) and DNA-protein crosslinks, and induces cellular death. Therefore, outlining the cytogenetic effects induced by X-ray is necessary to identify the degree of cancer risk and minimize potential risks to patients and clinicians. To date, a variety of assays have been proposed in cytogenetic biomonitoring studies, including those that assess metaphase chromosomal aberrations and sister chromatid exchanges, and micronucleus and single-cell gel (comet) assay. METHODS: Cytogenetic biomonitoring studies focusing on oral mucosa cells in individuals exposed to dental X-ray were reviewed. RESULTS: Dental X-ray can induce DNA damage and cytotoxicity in oral mucosa cells. CONCLUSION: These results will contribute to a better understanding of X-ray-induced effects upon the cellular system in individuals continually exposed to known genotoxic/cytotoxic agents.

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OBJECTIVES: To evaluate the DNA damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated buccal mucosa cells from children undergoing orthodontic radiographs. MATERIALS AND METHODS: A total of 25 healthy children undergoing orthodontic therapy partook in a complete set of orthodontic radiographs (lateral cephalographic, posteroanterior cephalographic, panoramic, full periapical exam, and bitewing). The micronucleus test in the buccal exfoliated cells was applied. The paired-samples t-test and the Wilcoxon test were used to compare the frequencies of alterations before and after X-ray exposure. RESULTS: We found no statistically significant differences (P > .05) between micronucleated buccal mucosa cells before and after exposure to radiation. However, radiation did cause other nuclear alterations closely related to cytotoxicity (P  =  .007). CONCLUSION: According to the micronucleus test, the complete set of radiographs requested in the orthodontic planning may not be a factor that induces chromosomal damage, but it is able to promote cytotoxicity.

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Exames radiográficos para fins de saúde constituem a principal fonte de exposição da população a radiação ionizante artificial, devendo empregar a dose mínima necessária para que se obtenha imagem de qualidade. Colimadores retangulares têm sido propostos em substituição aos circulares para reduzir a exposição de órgãos críticos. Este estudo teve por objetivo verificar se existe diferença na dose de radiação nas regiões de cristalino e tireóide durante a realização de um exame periapical completo, em função da forma e do tamanho do colimador utilizado. Trinta pacientes foram aleatoriamente distribuídos em três grupos: 1 - colimador circular convencional com 60 mm de diâmetro; 2 - colimador retangular com 24 x 32 mm² e 3 - colimador retangular com 30 x 40 mm². As condições de exame foram padronizadas para os três grupos. A dose foi obtida por meio de dosímetros termoluminescentes de LiF:Mg.Cu.P (TLD-100H), que permaneceram, durante a execução das 14 radiografias do exame completo periapical, posicionados sobre os olhos (cristalino) direito e esquerdo e sobre a região da tireóide, abaixo do protetor plumbífero. Os resultados finais foram submetidos aos testes não-paramétricos de Kruskal-Wallis e Friedman, ambos complementados por seus testes de comparações múltiplas, ao nível de significância de 5%. No grupo 2 houve redução significativa na dose de radiação absorvida na região dos olhos em relação aos grupos 1 e 3. Os grupos 2 e 3 apresentaram redução significativa na dose de radiação absorvida na tireóide em relação ao grupo 1. Nos três grupos, a dose absorvida na região dos olhos e significativamente maior do que a dose absorvida pela tireóide. O uso do colimador retangular reduziu significativamente a dose absorvida na tireóide.

X rays examinations are the main source of population's exposure to artificial ionizing radiation. Radiation dose in such examinations should be as low as possible but still ensuring a good image quality. Rectangular collimators have been proposed in substitution to the circular ones in order to minimize the radiation exposure to nearby critical organs. This study aims to compare the radiation doses in the lens of the eyes (right and left) and thyroid gland obtained using different collimators, in a complete periapical examination (14 radiographic exposures). Thirty patients have been randomly allocated to three groups: 1 - using a 60 mm diameter conventional circular collimator; 2 - using a 24 x 32 mm² rectangular collimator; and 3 - using a 30 x 40 mm² rectangular collimator. The doses were measured by LiF:Mg,Cu,P thermoluminescent dosimeters (TLD-100H) positioned over both right and left eyes and under the lead thyroid protector shield, in the thyroid gland position. Final results were submitted to Kruskal-Wallis and Friedman non-parametric statistics analysis, complemented by multiple comparison tests, with 5% significance level. Group 2 presented a significant dose reduction in the eyes region compared to groups 1 and 3. Groups 2 and 3 showed a significant dose reduction in the thyroid gland region compared to group 1.

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O objetivo deste estudo foi avaliar a influência da sensibilidade do filme radiográfico intrabucal e experiência do examinador na detecção de lesão periapical artificialmente produzida. Antes e após a confecção de elsão periapical em mandíbula seca, foram realidas radiografias periapicais com filmes de diferentes sensibilidades: E (Kodak Insight, processado anualmente), D (Kodak Ultra-spedd) e E (Agfa M2 Confort). As radiografias obtidas foram analisadas sobre o negatoscópio, por dois diefrentes examinadores, que utilizaram uma escala de cinco níveis para indicar a presença ou não da lesão óssea. plotadas as curvas ROC, os resultados demonstarram que, para o examinador 1, os três filmes exibiram curvas idênticas valor ROC = 1). Para o examinador 2, as curvas ROC demonstraram um melhor desempenho para o filme Ultra-sped (valor ROC = 0,88), seguido pelo M2 Confort (valor ROC = 0,76) e Insight (valor ROC = 0,50)

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Os autores mediram as doses de radiaçäo recebidas por trinta e três pacientes, divididos em três grupos de onze, utilizando a técnica periapical do paralelismo, com catorze tomadas radiográficas de cada paciente. Em cada grupo, foram utilizados os tempos de exposiçäo de 0,3 0,5 e 0,8s. Foram colocados em cada paciente de dois cristais de fluoreto de lítio TLD-100 na altura dos forames infra-orbitários direito e esquerdo. Após as leituras dos cristais utilizados nos pacientes, foi possível determinar os valores correspondentes da dose de radiaçäo por meio de uma curva de padronizaçäo. Obtendo-se todos os valores, concluiram-se as porcentagens de acréscimos das doses de radiaçäo com os diferentes tempos de exposiçäo utilizados

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