There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: 1) axial, coronal and sagittal multiplanar reconstruction (MPR); and 2) sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill # 1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis.

Computed tomography (CT) is used in several clinical dentistry applications even by axial slices and two and three-dimensional reconstructed images (2D-CT and 3D-CT). The purpose of the current study is to assess the precision of linear measurements made in 3D-CT using craniometric patterns for individual identification in Forensic Dentistry. Five cadaver heads were submitted to a spiral computed tomography using axial slices, and 3D-CT reconstructions were obtained by volume rendering technique with computer graphics tools. Ten (10) craniometric measurements were determined in 3D-CT images by two examiners independently, twice each, and the standard error of intra- and inter-examiner measurements was assessed. The results demonstrated a low standard error of those measurements, from 0.85% to 3.09%. In conclusion, the linear measurements obtained in osseous and soft tissue structures were considered to be precise in 3D-CT with high imaging quality and resolution.

The objective of this study was to evaluate spiral-computed tomography (3D-CT) images of 20 patients presenting with cysts and tumors in the maxillofacial complex, in order to compare the surface and volume techniques of image rendering. The qualitative and quantitative appraisal indicated that the volume technique allowed a more precise and accurate observation than the surface method. On the average, the measurements obtained by means of the 3D volume-rendering technique were 6.28% higher than those obtained by means of the surface method. The sensitivity of the 3D surface technique was lower than that of the 3D volume technique for all conditions stipulated in the diagnosis and evaluation of lesions. We concluded that the 3D-CT volume rendering technique was more reproducible and sensitive than the 3D-CT surface method, in the diagnosis, treatment planning and evaluation of maxillofacial lesions, especially those with intra-osseous involvement.

The aim of this study was to evaluate the precision and accuracy of linear measurements of maxillary sinus made in tomographic films, by comparing with 3D reconstructed images. Linear measurements of both maxillary sinus in computed tomography CT of 17 patients, with or without lesion by two calibrated examiners independently, on two occasions, with a single manual caliper. A third examiner has done the same measurements electronically in 3D-CT reconstruction. The statistical analysis was performed using ANOVA (analyses of variance). Intra-observer percentage error was little in both cases, with and without lesion; it ranged from 1.14% to 1.82%. The inter-observer error was a little higher reaching a 2.08% value. The accuracy presented a higher value. The perceptual accuracy error was higher in samples, which had lesion compared to that which had not. CT had provided adequate precision and accuracy for maxillary sinus analyses. The precision in cases with lesion was considered inferior when compared to that without lesion, but it can't affect the method efficacy.

CAVALCANTI, M. de G. P.; TOSSATO, P. dos S.; GUIDA, F. J.; DUAIK, M. C. A.; KUROISHI, M. Análise de carcinomas epidermóides por meio de radiografia panorâmica e tomografia computadorizada. Pesqui Odontol Bras, v. 15, n. 4, p. 320-326, out./dez. 2001. Este trabalho teve como objetivo correlacionar aspectos radiográficos como, localização e extensão do tumor, infiltração óssea e de tecidos moles e destruição das corticais, obtidos nas radiografias panorâmicas com os encontrados nas tomografias computadorizadas (TCs). Os aspectos radiográficos de 48 pacientes com diagnóstico histopatológico de carcinomas epidermóides, localizados em várias regiões do complexo buco-maxilo-facial, foram analisados por 4 radiologistas. As radiografias panorâmicas e as tomografias computadorizadas foram realizadas nos hospitais e clínicas da Universidade de Iowa (EUA), FUNDECTO -USP e Hospital Universitário da Universidade de São Paulo (SP, Brasil). Como resultados, obtivemos a grande limitação da radiografia panorâmica em determinar a localização e extensão do tumor, com delimitações bastante imprecisas da lesão. Já as TCs ofereceram resultados mais direcionados como: invasão do tumor em direção a estruturas moles adjacentes, extensão da destruição óssea, bem como a profundidade da lesão, que foram confirmados com os achados cirúrgicos. Concluímos que a tomografia computadorizada demonstrou ser uma técnica bastante sensível na detecção do comprometimento ósseo e do envolvimento de tecidos moles, proporcionando, assim, o auxílio no diagnóstico e no planejamento do tratamento. No entanto, a radiografia panorâmica foi muito pouco sensível e eficaz, por mostrar apenas margens imprecisas e pouco nítidas da lesão, não avaliando o envolvimento de tecidos moles. UNITERMOS: Carcinoma de células escamosas; Radiografia panorâmica; Tomografia computadorizada por raios X. INTRODUÇÃOCarcinomas epidermóides são os tumores com maior prevalência na cavidade oral, perfazendo 91% de todas as neoplasias malignas encontradas nesta região 17 . A incidência desta neoplasia na mandíbula é de 12% a 56% de acordo com vários estudos 2,3,14,22,25,26,27,26 . Os carcinomas epidermóides são mais freqüentes na mandíbu-la, ocorrendo duas ou três vezes mais do que na maxila 4,11,30 , podendo atingir várias áreas da cavidade bucal, como: glândulas parótidas e submandibulares, língua, assoalho bucal, palato, seios maxilares, orofaringe, região retromolar e processo alveolar.Vários métodos radiográficos são utilizados para determinar a invasão e extensão do carcinoma epidermóide. No estágio inicial da doença, esta pode ser identificada através de um exame rotineiro 20,21 , porém em estágios mais avançados é muito difícil a determinação da lesão em radiografias panorâmicas. O diagnóstico deve ser feito com base em radiografias conjugadas. A tomografia computadorizada (TC) apresenta inúmeros cortes, o que possibilita a interpretação com imagens conjugadas 10,12,13,18,23 . 320 Radiologia

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In this paper we present the aspect of a mandibular giant cell granuloma in spiral computed tomography-based three-dimensional (3D-CT) reconstructed images using computer graphics, and demonstrate the importance of the vascular protocol in permitting better diagnosis, visualization and determination of the dimensions of the lesion. We analyzed 21 patients with maxillofacial lesions of neoplastic and proliferative origins. Two oral and maxillofacial radiologists analyzed the images. The usefulness of interactive 3D images reconstructed by means of computer graphics, especially using a vascular setting protocol for qualitative and quantitative analyses for the diagnosis, determination of the extent of lesions, treatment planning and follow-up, was demonstrated. The technique is an important adjunct to the evaluation of lesions in relation to axial CT slices and 3D-CT bone images.

Metallic objects, such as intracanal posts and restorations, may produce severe interference, thus diminishing the quality of CBCT imaging. Objective: The purpose of this study was to analyze the influence of conventional and bioceramic gutta-percha points on the production of artifacts in CBCT images. Methods: Extracted single- -rooted premolar teeth (n=20) were instrumented and scanned with a CBCT device to create three groups: the Control group, the Gutta-Percha group and the Bioceramic Gutta-Percha group. Two types of analysis were executed: an objective one, using the Region of Interest (ROI) to measure the pixel density of each tooth, and a subjective one, to compare the groups’ images. For the statistical analysis, Student’s t-test, descriptive statistics and the frequency distribution analysis were used for both objective and subjective analyses. Results: The agreement between the observers ranged from moderate to excellent. Similar grayscale values were obtained in both the GP and BCGP groups. These results were endorsed by the p-values obtained with Student’s t test. For the subjective analysis, the observers indicated the BCGP group as the one that developed the highest number of artifacts. Conclusions: Both materials produced artifacts in the CBCT images. However, in the subjective analysis, the BCGP group showed higher levels of artifact production than the GP group, which could result in the misdiagnosis of root fracture and in a worse prognosis for that tooth.