ABSTRACT
Objective: To evaluate the use of nanosilver fluoride in the enamel remineralization process through optical coherence tomography. Material and Methods: All samples were submitted to demineralization process by pH cycling during 14 days and randomly distributed into three groups (n = 11): Nanosilver Fluoride (NSF), Sodium fluoride (NaF), and negative control. Optical coherence tomography images were acquired at three different moments: initial stage (T0), post caries formation (T1), and post pH cycling (T2). The integrity of the enamel surface and the measurement of the volume loss for the tissue after pH cycling in comparison to initial images were obtained from optical coherence tomography images. Results: After analyzing the exponential decay of A-scans from each group, it was possible to identify differences in light propagation among samples. In T1 it is not possible to visualize the dentin-enamel junction, probably due to the higher back scattering of the demineralized enamel, which does not allow light to reach the dentin. The decay curves obtained from NaF and nanosilver fluoride groups showed similar behavior, while the negative group showed lower extinction coefficient. Conclusion: Nanosilver fluoride showed the best effect against caries compared to conventional fluoride treatments.
Subject(s)
Tooth Demineralization/diagnosis , Nanotechnology/methods , Dental Enamel , Tomography, Optical Coherence/methods , Fluorides , In Vitro Techniques/methods , BrazilABSTRACT
O uso de interação da luz com a matéria não é um conceito novo em biologia para a detecção de processos físico-químicos, embora ainda seja utilizado de uma forma rudimentar. Já é sabido que imagens de refletância e fluorescência podem revelar informações importantes sobre tais processos em amostras biológicas. Apesar deste potencial, os sistemas experimentais disponíveis para a obtenção de tais imagens costumam serem complexos e de difícil implementação. Neste trabalho é descrita a construção e a caracterização de uma montagem experimental para produção de imagens hiperespectrais entre 400 e 1.000 nm. O sistema é composto de um espectrômetro, um conjunto de lentes para formação da imagem e uma câmera CCD para capturá-la. São descritos em detalhes o procedimento de calibração do sistema, o qual envolve os parâmetros largura da imagem, campo de visão, resolução espectral e espacial. O sistema de iluminação utiliza diodos emissores de luz de alta potência, tanto de luz branca quanto em 470 e 405 nm. Demonstramos que o sistema construído é capaz de obter imagens de fluorescência e/ou refletância de amostras biológicas. Como exemplos de aplicações, o instrumento aqui desenvolvido foi utilizado em dois campos distintos, a agricultura e a odontologia. Foram obtidas imagens de fluorescência de folhas de citros contaminadas com cancro cítrico, e de processos de desmineralização em dentes. Os resultados demonstram que o sistema construído está operando como projetado.
The use of light-mater interaction for the detection of chemicalphysical processes is not a new concept in biology, though it is still used in a rudimentary form. It is already known that reflectance as well as fluorescence images can reveal important information on such processes in biological samples. In spite of this potential, the experimental available image systems usually are complexes and of difficult implementation. In this work, we describe the construction and characterization of an experimental device to produce hyperspectral images between 400 and 1,000 nm. The system is composed of a spectrometer, a set of lenses for image formation and a CCD camera to capture it. We describe in details also the calibration procedure of the system, which involves parameters as image width, field of view, spectral and space resolution. The illumination system uses high power light emitting diodes, either at white light or at 470 and 405 nm. We demonstrate that our system is able to obtain reflectance as well as fluorescence images of biological samples. As examples of applications, we use it into two different fields, agriculture and dentistry. We obtained fluorescence images of citrus leaves contaminated with citrus canker and demineralization processes in teeth. Our results demonstrate that our system isoperating as designed.