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Item Enamel erosion prevention and mechanism: effect of 10.6-μm wavelength CO2 laser low power density irradiation studied by X-ray fluorescence and infrared spectroscopy and scanning electron microscopy(Springer Nature Link) Lopes, Francialza Veras Viana; Sanches, Roberto Pizarro; Vasconcelos, Getúlio de; Bhattacharjee, Tanmoy T.; Santo, Ana Maria do Espírito; Soares, Luís Eduardo SilvaPurpose This study assessed the effects of carbon dioxide (CO2) laser (λ = 10.6 μm, 5 W, 70 J/cm2) irradiation alone and after treatment with neutral fluoride gel on enamel and their efficacy in preventing enamel erosion compared to untreated and fluoride gel-treated enamel. Methods Enamel surfaces of the bovine incisor (n = 7/group) were treated with artificial saliva (S, negative control), neutral fluoride (NF, positive control), CO2 laser irradiation (L), and NF + laser (NF + L). Samples were acid demineralized (soft drink, pH ~ 3.2, 10 min), remineralized (saliva, 37 °C, 1 h), and analyzed using micro-energy-dispersive X-ray fluorescence spectrom- etry (μ-EDXRF), attenuated total reflectance–Fourier-transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). Results Results suggest that NF gives the best protection against erosion, followed by NF + L and L. μ- EDXRF showed that changes due to laser treatment in L and NF + L were uneven. SEM images showed morphological changes in L and NF + L such as craters, fissures, and roughness in some regions, again indicating the unevenness of laser-induced enamel changes. ATR-FTIR mean spectra intensity levels and principal component analysis also indicate higher efficacy of fluoride over laser treatments and unevenness of laser treatments. Conclusion Overall, it can be concluded that CO2 laser parameters need to be further investigated to promote adequate protection with minimum surface changes.Item Combined morphological-compositional analysis of the interaction of collagen and chitosan based-materials with demineralized bovine dentin(Brazilian Journals Publicações de Periódicos) Nahórny, Sidnei; Oliveira, Ivone Regina de; Soares, Luís Eduardo SilvaTreatments to promote the biomineralization of dentin are the focus of much research with different materials and processes. Biomineralization is a process mediated by an organic matrix in which organic macromolecules act as models for the nucleation and growth of mineral crystals to form hierarchically ordered hybrid materials, such as bones or teeth. This study describes the application of novel materials based on collagen and chitosan aimed to protect the dentin from erosive conditions. The dentin morphology of the bovine teeth treated with these materials was visualized using scanning electron microscopy (SEM). In additions, it was possible to confirm the data by analyzing the distribution of inorganic content of dentin by micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF). The association of analytical techniques demonstrated greater surface coverage for the chitosan-fluoride followed by the hydrolyzed collagen. Both materials are promising for the application of dentin coverage in dentistry.