Three-dimensional imaging modalities have been reported to be more accurate than panoramic radiographs (PR) for the assessment of bone components of the temporomandibular joint (TMJ). No exact prior information is available that demonstrates which specific limitations occur in terms of TMJ diagnosis when using PR for this purpose. This study aimed to assess the clinical validity of digital panoramic radiography (DPR) when diagnosing morphological disorders of the TMJ using cone-beam computed tomography (CBCT) images as the gold standard. A sample composed of TMJ images (N = 848), including 212 DPR and 212 CBCT images obtained from the same patient, was used to assess any morphological changes in the TMJ. Four appraisers diagnosed all of the DPR images, whereas the CBCT images were used to establish the gold standard. The reliability of each appraiser’s response pattern was analyzed using the Kappa test (κ), and diagnostic tests were performed to assess each appraiser’s performance using a significance level setting of 5% (α = 0.05). Reliability of each appraiser’s response pattern compared to the gold standard ranged from a slight-to-moderate agreement (0.18 ≤ κ ≤ 0.45); and among the different appraisers, the response pattern showed a fair agreement (0.22 ≤ κ ≤ 0.39). Diagnostic tests showed a wide range among the different possible morphological changes diagnosed. DPR does not have validity when diagnosing morphological changes in the TMJ; it underestimates the radiological findings with higher prevalence, and thus, it cannot be used effectively as a diagnostic tool for bone components within this region.

The aim of this study was to use cone-beam computed tomography (CBCT) images to evaluate the prevalence and configurations of C-shaped canals in permanent mandibular second molars among members of a Brazilian subpopulation. CBCT exams of 214 patients (406 teeth) were evaluated for: presence of C-shaped root canals, number of canals and direction of the root grooves (buccal or lingual). Of the 214 CBCT images examined, 192 showed intact bilateral molars, which were used to analyze the distribution of unilateral and bilateral occurrences of C-shaped canals. The prevalence of these canals was correlated with gender and age, and the number of canals was correlated with the direction of the root grooves using the chi-squared test (α = 0.05). The prevalence of C-shaped canals was 15.3%. This prevalence did not differ with gender or age. Most of the C-shaped molars had three (43.5%) or two (37.1%) canals; 69.4% of the C-shaped canals were grooved in the buccal direction; 68.3% of the C-shaped cases were unilateral. In conclusion, there was a significant prevalence of C-shaped canals in the mandibular second molars of the population studied; the C-shaped canal system varied in configuration, with a higher prevalence of three and two canals and unilateral occurrence; CBCT is a useful tool for endodontic diagnosis and treatment.

O objetivo na presente pesquisa foi determinar o tamanho, forma e posição da camada de imagem por meio da avaliação da formação da imagem radiográfica em diferentes posições anatômicas. Foi construído um phantom constituído por uma placa acrílica de 14 cm² e 0,3 cm de espessura, com sua superfície contendo perfurações a cada 0,5 cm dispostas em linhas e colunas. O phantom foi posicionado no local do apoio de mento do aparelho panorâmico, com sua superfície paralela ao plano horizontal. Esferas metálicas de 0,315 cm foram inseridas nas perfurações, e executadas radiografias panorâmicas. Cada coluna de cada quadrante foi individualmente preenchida pelas esferas para a execução das radiografias, em três planos horizontais diferentes: alturas orbital, oclusal e mentual. As imagens das esferas foram medidas com o uso de um paquímetro digital e a camada de imagem localizada. Os dados foram analisados estatisticamente utilizando-se o teste T Student, ANOVA e teste de Tukey (?=0,05). Quando o tamanho das esferas nos eixos horizontal e vertical foi comparado, diferenças estatisticamente significativas (p<0,05) foram observadas em todas as áreas da camada de imagem, porções e alturas do plano horizontal avaliado. Na porção central da camada de imagem diferenças no tamanho das esferas foram observadas somente no eixo horizontal (p<0,05), enquanto que no eixo vertical nenhuma diferença foi observada (p>0,05). A metodologia utilizada determinou com precisão o tamanho, forma e posição da camada de imagem, e diferenças de ampliação foram observadas tanto no eixo horizontal quanto vertical.

The aim of this study was to determine size, shape and position of the image layer by evaluation of the radiographic image formation in different anatomic positions. A customized phantom was made of a rectangular acrylic plate measuring 14 cm² and 0.3 cm thick, with holes spaced 0.5 cm away and arranged in rows and columns. Each column was separately filled with 0.315 cm diameter metal spheres to acquire panoramic radiographs using the Orthopantomograph OP 100 unit. The customized phantom was placed on the mental support of the device, with its top surface kept parallel to the horizontal plane, and was radiographed at three different heights from the horizontal plane, i.e., the orbital, occlusal and mandibular symphysis levels. The images of the spheres were measured using a digital caliper to locate the image layer. The recorded data were analyzed statistically by the Student'-t test, ANOVA and Tukey' test (?=0.05). When the image size of spheres in horizontal and vertical axes were compared, statistically significant differences (p<0.05) were observed in all areas, portions of the image layer and heights of horizontal plane evaluated. In the middle portion of the image layer, differences in the image size of spheres were observed only along the horizontal axis (p<0.05), whereas no differences were observed along the vertical axis (p>0.05). The methodology used in this determined the precise size, shape and position of the image layer and differences in magnification were observed in both the horizontal and vertical axes.