Abstract
Erosion is a highly prevalent condition known as a non-carious lesion that causes progressive tooth wear due to chemical processes that do not involve the action of bacteria. Speckle images proved sensitive to even minimal mineral loss from the enamel. The aim of the present study was to investigate the use of laser speckle imaging analysis in the spatial domain to quantify shifts in the microstructure of the tooth surface in an erosion model. 32 fragments of the vestibular surface of bovine incisors were divided in for groups (10 min, 20 min. 30 min and 40 min of acid etching) immersed in a cola-based beverage (pH approximately 2.5) twice a day during 7 days to create an artificial erosion. By analyzing the laser speckle contrast map (LASCA) in the eroded region compared to the sound it was observed that the LASCA map shifts, proportionally to the acid each duration, by: 18%; 23%; 39% and 44% for the 10 min; 20 min; 30 min and 40 min groups, respectively. To the best of our knowledge, this is the first study to demonstrate the correlation between speckle patterns and erosion progression.
Highlights
Laser speckle imaging is a diagnostic technique in which the features of scattered coherent light are explored
The standard deviation of each sample was larger in the eroded tissue in comparison to the sound tissue (Fig. 4). Both effects are related to the heterogeneity induced in the microstructure of the enamel by the demineralization process, which increases the interprismatic spaces, exposing the top of the prism, which has greater porosity [21]. This increases the number of scattering centers, thereby increasing the light scattering, but mineral loss reduces the backscattering coefficient
To the best of our knowledge, this is the first study to demonstrate it is possible to analyze information on the microstructure of tooth enamel after an acid etching procedure using patterns and laser speckle contrast map (LASCA) maps
Summary
Laser speckle imaging is a diagnostic technique in which the features of scattered coherent light are explored. The image of the scatter pattern contains information on the microstructure and micro-movements of the surface of a given tissue. By employing statistical analysis of the temporal and spatial fluctuations in the light scattered by microstructure dynamics and heterogeneities, it is possible to extract information on the dynamics of the abdominal wall in rats, pulp vitality in teeth and cerebral blood flow. The ability of laser speckle imaging to allow the evaluation of dynamic features in tissues using a non-invasive, non-destructive cost-effective, real-time method has stimulated the academic community to focus efforts on the study of this method in the time domain (dynamic speckle analysis). The analysis of speckle patterns in the spatial domain contains information on the microstructure and heterogeneities of the surface, which can be explored.
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