New method of assessing the relationship between buccal bone thickness and gingival thickness

PURPOSE: The aim of this study was to determine the relationship between buccal bone thickness and gingival thickness by means of a noninvasive and relatively accurate digital registration method. METHODS: In 20 periodontally healthy subjects, cone-beam computed tomographic images and intraoral scanned files were obtained. Measurements of buccal bone thickness and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0–5 mm from the alveolar crest on the superimposed images. The Friedman test was used to compare buccal bone and gingival thickness for each depth between the 3 tooth types. Spearman's correlation coefficient was calculated to assess the correlation between buccal bone thickness and gingival thickness. RESULTS: Of the central incisors, 77% of all sites had a buccal thickness of 0.5–1.0 mm, and 23% had a thickness of 1.0–1.5 mm. Of the lateral incisors, 71% of sites demonstrated a buccal bone thickness <1.0 mm, as did 63% of the canine sites. For gingival thickness, the proportion of sites <1.0 mm was 88%, 82%, and 91% for the central incisors, lateral incisors, and canines, respectively. Significant differences were observed in gingival thickness at the alveolar crest level (G0) between the central incisors and canines (P=0.032) and between the central incisors and lateral incisors (P=0.013). At 1 mm inferior to the alveolar crest, a difference was found between the central incisors and canines (P=0.025). The lateral incisors and canines showed a significant difference for buccal bone thickness 5 mm under the alveolar crest (P=0.025). CONCLUSIONS: The gingiva and buccal bone of the anterior maxillary teeth were found to be relatively thin (<1 mm) overall. A tendency was found for gingival thickness to increase and bone thickness to decrease toward the root apex. Differences were found between teeth at some positions, although the correlation between buccal bone thickness and soft tissue thickness was generally not significant.

Distance learning in dental radiology: immediate impact of the implementation / Educação à distância em radiologia odontológica: Impacto imediato da implantação

Objective: This study assessed the immediate impact in terms of learning dento-maxillomandibular radiographic anatomy in intraoral periapical radiographs after entire replacement of the method of classroom learning by the distance learning using the Moodle platform. Material and Methods: Teaching of this subject by traditional educational setting in classroom was made until the first semester of 2011, “A class” (AC), using radiographic slabs from duplicated films with imprints indicating anatomical structures in images that is accompanied by textbook with its description and support teacher, who works closely with the classroom to support student learning. In the second semester of 2011, “B class” (BC), these same radiographic slabs were digitalized, including description of textbook, creating the Moodle e-course about dentomaxillomandibular anatomy in intraoral radiographs for distance learning. The impact was assessed by comparison of scores of students from two distinct classes, AC (N = 60) and BC (N = 62), after application of a similar test with all content of the topic of dento-maxillomandibular anatomy, using T-Student unpaired test (α = 0.05). A voluntary and unidentified questionnaire with 12 questions, developed in Google Docs spreadsheets, was used to evaluate the acceptance of students for this e-course. Results: No significant differences (p > 0.05) were observed in scores of the students from two classes. Among other questions, all students of BC who completed the questionnaire had interest in content of the available material in e-course, and their satisfaction level on a scale from 0 to 10 had a mean of 8.47 (SD = 1.69). Conclusion: The method of distance learning of this subject using the Moodle platform can be utilized with same educational results as of those obtained from a traditional educational setting...

Objetivo: Este estudo avaliou o impacto imediato em termos de aprendizagem da anatomia radiográfica dento-maxilo-mandibular em radiografias periapicais intrabucais, após toda a substituição do método de ensino em sala de aula pela educação a distância com a plataforma Moodle. Material e Métodos: O ensino desta disciplina no ambiente educacional tradicional em sala de aula foi feito até o primeiro semestre de 2011, classe A (AC), utilizando pranchas de filmes radiográficos duplicados com marcações que indicavam estruturas anatômicas nas imagens eum livro texto com a descrição da referida estrutura, além de professor de apoio, que trabalhava na sala de aula junto com os alunos como apoio de aprendizagem. No segundo semestre de 2011, para a “classe B” (BC), essas mesmas pranchas radiográficas foram digitalizadas, incluindo a descrição do livro texto, para criar o curso digital Moodle sobre anatomia dentomaxilo- mandibular em radiografias intra-orais para educação a distância. O impacto dessa substituição foi avaliado pela comparação das notas dos alunos dessas duas classes distintas, AC (N= 60) e BC (N = 62), após a aplicação de uma prova semelhante com todo o conteúdo do tema da anatomia dentomaxilo- mandibular, utilizando teste T-Student não pareado (α = 0,05). Um questionário voluntário e não identificado com 12 questões, desenvolvido em planilhas do Google Docs, foi utilizado para avaliar a aceitação dos alunos em relação ao curso digital. Resultados: Não houve diferença significativa (p > 0,05) entre as notas dos alunos das duas classes. Em relação às respostas do questionário, todos os alunos da BC que responderam ao questionário tinham interesse no conteúdo do material disponível no curso digital e o nível de satisfação medido em uma escala de 0 a 10 obteve média de 8,47 (DP = 1,69)...

Computer-aided detection system for masses in automated whole breast ultrasonography: development and evaluation of the effectiveness

PURPOSE: The aim of this study was to evaluate the performance of a proposed computer-aided detection (CAD) system in automated breast ultrasonography (ABUS). METHODS: Eighty-nine two-dimensional images (20 cysts, 42 benign lesions, and 27 malignant lesions) were obtained from 47 patients who underwent ABUS (ACUSON S2000). After boundary detection and removal, we detected mass candidates by using the proposed adjusted Otsu's threshold; the threshold was adaptive to the variations of pixel intensities in an image. Then, the detected candidates were segmented. Features of the segmented objects were extracted and used for training/testing in the classification. In our study, a support vector machine classifier was adopted. Eighteen features were used to determine whether the candidates were true lesions or not. A five-fold cross validation was repeated 20 times for the performance evaluation. The sensitivity and the false positive rate per image were calculated, and the classification accuracy was evaluated for each feature. RESULTS: In the classification step, the sensitivity of the proposed CAD system was 82.67% (SD, 0.02%). The false positive rate was 0.26 per image. In the detection/segmentation step, the sensitivities for benign and malignant mass detection were 90.47% (38/42) and 92.59% (25/27), respectively. In the five-fold cross-validation, the standard deviation of pixel intensities for the mass candidates was the most frequently selected feature, followed by the vertical position of the centroids. In the univariate analysis, each feature had 50% or higher accuracy. CONCLUSION: The proposed CAD system can be used for lesion detection in ABUS and may be useful in improving the screening efficiency.

Radiopacity of restorative composites by conventional radiograph and digital images with different resolutions

PURPOSE: This study was performed to evaluate and compare the radiopacity of dentin, enamel, and 8 restorative composites on conventional radiograph and digital images with different resolutions. MATERIALS AND METHODS: Specimens were fabricated from 8 materials and human molars were longitudinally sectioned 1.0 mm thick to include both enamel and dentin. The specimens and tooth sections were imaged by conventional radiograph using #4 sized intraoral film and digital images were taken in high speed and high resolution modes using a phosphor storage plate. Densitometric evaluation of the enamel, dentin, restorative materials, a lead sheet, and an aluminum step wedge was performed on the radiographic images. For the evaluation, the Al equivalent (mm) for each material was calculated. The data were analyzed using one-way ANOVA and Tukey's test (p<0.05), considering the material factor and then the radiographic method factor, individually. RESULTS: The high speed mode allowed the highest radiopacity, while the high resolution mode generated the lowest values. Furthermore, the high resolution mode was the most efficient method for radiographic differentiation between restorative composites and dentin. The conventional radiograph was the most effective in enabling differentiation between enamel and composites. The high speed mode was the least effective in enabling radiographic differentiation between the dental tissues and restorative composites. CONCLUSION: The high speed mode of digital imaging was not effective for differentiation between enamel and composites. This made it less effective than the high resolution mode and conventional radiographs. All of the composites evaluated showed radiopacity values that fit the ISO 4049 recommendations.