Laboratorial training of examiners for using a visual caries detection system in epidemiological surveys

Background: In epidemiological surveys, a good reliability among the examiners regarding the caries detection method is essential. However, training and calibrating those examiners is an arduous task because it involves several patients who are examined many times. To facilitate this step, we aimed to propose a laboratory methodology to simulate the examinations performed to detect caries lesions using the International Caries Detection and Assessment System (ICDAS) in epidemiological surveys. Methods: A benchmark examiner conducted all training sessions. A total of 67 exfoliated primary teeth, varying from sound to extensive cavitated, were set in seven arch models to simulate complete mouths in primary dentition. Sixteen examiners (graduate students) evaluated all surfaces of the teeth under illumination using buccal mirrors and ball-ended probe in two occasions, using only coronal primary caries scores of the ICDAS. As reference standard, two different examiners assessed the proximal surfaces by direct visual inspection, classifying them in sound, with non-cavitated or with cavitated lesions. After, teeth were sectioned in the bucco-lingual direction, and the examiners assessed the sections in stereomicroscope, classifying the occlusal and smooth surfaces according to lesion depth. Inter-examiner reproducibility was evaluated using weighted kappa. Sensitivities and specificities were calculated at two thresholds: all lesions and advanced lesions (cavitated lesions in proximal surfaces and lesions reaching the dentine in occlusal and smooth surfaces). Conclusion: The methodology purposed for training and calibration of several examiners designated for epidemiological surveys of dental caries in preschool children using the ICDAS is feasible, permitting the assessment of reliability and accuracy of the examiners previously to the survey´s development.

Fast detection of the magnetic easy axis on steel sheet using the continuous rotational Barkhausen method

The magnetic behaviour of most commercial ferromagnetic steels is usually anisotropic presenting a magnetic easy axis. Changes in the direction of this axis can be related to mechanical changes and anomalies that occur in the fabrication process. The present work describes a method that uses a device with permanent magnets to create a precise rotational magnetic field. The device measures continuous Magnetic Barkhausen Noise signals related to the angle of magnetization, in order to determine the direction of the macroscopic magnetic easy axis. It also offers the possibility of obtaining real time parameters that quantify the magnetic anisotropy of the sample. (C) 2011 Elsevier Ltd. All rights reserved.

Development of an enzymeless electroanalytical method for the indirect detection of creatinine in urine samples

The aim of this study is to develop a new enzymeless electroanalytical method for the indirect quantification of creatinine from urine sample. This method is based on the electrochemical monitoring of picrate anion reduction at a glassy carbon electrode in an alkaline medium before and after it has reacted with creatinine (Jaffe's reaction). By using the differential pulse voltammetry technique under the optimum experimental conditions (step potential, amplitude potential, reaction time, and temperature), a linear analytical curve was obtained for concentrations of creatinine ranging from 1 to 80 mu mol L-1, with a detection limit of 380 nmol L-1. This proposed method was used to measure creatinine in human urine without the interference of most common organic species normally present in biological fluids (e.g., uric acid, ascorbic acid, glucose, and phosphocreatinine). The results obtained using urine samples were highly similar to the results obtained using the reference spectrophotometric method (at a 95% confidence level). (C) 2012 Elsevier B.V. All rights reserved.