PEDRO ARTHUR AUGUSTO DE CASTRO
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Resumo IPEN-doc 29575 Q-switched Nd:YAG laser on dental enamel with photoabsorber2022 - CASTRO, PEDRO; PEREIRA, DAISA; ANA, PATRICIA; MATOS, CHRISTIANO; ZEZELL, DENISENd:YAG lasers emitting λ=1064 nm at microsecond and nanosecond pulses are alternatives to prevent dental caries and erosion in clinics.This wavelength allows most of photons to penetrate deep in the hard tissue due to low absorption of hydroxyapatite in the region. It is necessary to use photoabsorbers so most of photons are absorbed in the surface of the tissue preventing dental pulp necrosis. Currently the coal paste is used as a photoabsorber but the irradiated tissue turns darker what implies in the patients low adherence to the treatment due to aesthetic reasons. [1,2]. Confocal Raman spectroscopy is a non-destructive optical method to obtain detailed information about molecular composition of biological structures in depth. The most prominent feature of Confocal Raman spectroscopy is the reliable capability to provide the biomolecular data with no use of ionizing radiation to penetrate in the sample. This work aims to characterize the dental enamel irradiated with Nd:YAG laser with nanoseconds pulses, in order to describe the depth related changes promoted in the enamel, by the heat generated due to laser irradiation. For these measurements, 30bovine enamel blocks of 8 mm2, were randomized into 3 groups: G1 – enamel untreated; G2 – enamel irradiated with Nd:YAG nanopulsed laser (1064 nm, 4 W; 1,05 J/cm2; 5 ns 20 Hz, Brilliant, Quantel Laser) using a coal paste as photoabsorber; G3 -enamel irradiated with Nd:YAG nanopulsed laser ( same parameters as G2) using squid ink as photoabsorber. The assessments of three different depth regions of the cubic shaped samples were: region A- left corner above of the sample, region B- middle of the sample and Region C- right corner below of the sample. The intensity map of phosphate (950 cm-1)regarding the position, were calculated [3,4] as shown in the Figure 01. The comparative results in the Fig.1 demonstrated that application of coal paste associated with Nd:YAG (G2) can preserve the inorganic content better than the squid ink group (G3). These findings have crucial clinical implications in the laser protocol development and itwas possible to correlate the heat penetration depth of the laser irradiation with photoabsorber using the images obtained bythe confocal Raman.Resumo IPEN-doc 28959 Q-switched Nd:YAG laser on dental enamel with photoabsorber2020 - CASTRO, P.; PEREIRA, D.; ANA, P.; MATOS, C.; ZEZELL, D.Nd:YAG lasers emitting λ = 1064 nm at microsecond and nanosecond pulses are alternatives to prevent dental caries and erosion in clinics. This wavelength allows most of photons to penetrate deep in the hard tissue due to low absorption of hydroxyapatite in the region. It is necessary to use photoabsorbers so most of photons are absorbed in the surface of the tissue preventing dental pulp necrosis. Currently the coal paste is used as a photoabsorber but the irradiated tissue turns darker what implies in the patients low adherence to the treatment due to aesthetic reasons. [1,2]. Confocal Raman spectroscopy is a non-destructive optical method to obtain detailed information about molecular composition of biological structures in depth. The most prominent feature of Confocal Raman spectroscopy is the reliable capability to provide the biomolecular data with no use of ionizing radiation to penetrate in the sample. This work aims to characterize the dental enamel irradiated with Nd:YAG laser with nanoseconds pulses, in order to describe the depth related changes promoted in the enamel, by the heat generated due to laser irradiation. For these measurements, 30 bovine enamel blocks of 8 mm2, were randomized into 3 groups: G1 – enamel untreated; G2 – enamel irradiated with Nd:YAG nanopulsed laser (1064 nm, 4 W; 1,05 J/cm2; 5 ns 20 Hz, Brilliant, Quantel Laser) using a coal paste as photoabsorber; G3 -enamel irradiated with Nd:YAG nanopulsed laser ( same parameters as G2) using squid ink as photoabsorber. The assessments of three different depth regions of the cubic shaped samples were: region A- left corner above of the sample, region B-middle of the sample and Region C- right corner below of the sample. The intensity map of phosphate (950 cm-1) regarding the position, were calculated [3,4] as shown in the Figure 01. The comparative results in the Fig.1 demonstrated that application of coal paste associated with Nd:YAG (G2) can preserve the inorganic content better than the squid ink group (G3). These findings have crucial clinical implications in the laser protocol development and it was possible to correlate the heat penetration depth of the laser irradiation with photoabsorber using the images obtained by the confocal Raman.Resumo IPEN-doc 28459 Confocal Raman spectroscopy characterization of Nd:YAG laser irradiation on dental enamel for erosion prevention2021 - CASTRO, PEDRO A.A.; PEREIRA, DAISA L.; ZEZELL, DENISE M.; RIBEIRO, HENRIQUE B.; MATOS, CHRISTIANO J.S.; ANA, PATRICIA A.Confocal Raman spectroscopy is a non-destructive and non-invasive method used to obtain spectral features of biological structure and depth images without coming into contact with the sample. Biochemical content obtained by Raman microscopy is related to the characteristics of the tissues, allowing experimental use without any side effects to the sample. Complex biomolecular features can be resolved through confocal Raman imaging analysis with subcellular spatial resolution by using a single excitation wavelength laser to identify a large range of biomolecules. This work aims to characterize dental enamel irradiated by Nd:YAG laser and correlate the modified tissue in depth due to the heat propagation caused by laser absorption. For this, 30 blocks of bovine enamel were randomized into 3 groups: G1- enamel untreated; G2- enamel irradiated with Nd:YAG laser (1064 nm; 120s pulsewidth, 10Hz; 84,9 mJ/cm2; Lares Research) using a squid Ink as photoabsorber; G3- enamel irradiated with Nd:YAG laser (1064 nm; 5 ns; 20 Hz; 1,05 J/cm2 Brilliant, Quantel Laser) using a coal paste as photoabsorber. The phosphate intensity band was used as a spectral indicator of the groups characteristics. The Raman spectra of the Nd:YAG irradiated samples detected a phosphate intensity reduction in the G3 group after laser irradiation. There were distinct differences in the chemical activity after the laser irradiation and these findings, associated with the previous studies of our group, were related to the stability of the apatite, accompanied with the increased susceptibility to demineralization. The carbonate free apatite has been characterized as less likely to be affected by acid challenge. Based on our initial results, the thickness of the treated area is a critical variable in determining the resistance of erosion, especially for the type of photoabsorber associated with Nd:YAG. Our findings demonstrate the coal paste as a more resistant material to enamel erosion prevention. Therefore, fiber-optic confocal Raman imaging have shown potential to be an established spectroscopic choice for carie real-time monitoring.Artigo IPEN-doc 28066 Assessment of the preventive effects of Nd:YAG laser associated with fluoride on enamel caries using optical coherence tomography and FTIR spectroscopy2021 - DIAS-MORAES, MARCIA C.; CASTRO, PEDRO A.A.; PEREIRA, DAISA L.; ANA, PATRICIA A.; FREITAS, ANDERSON Z.; ZEZELL, DENISE M.Objective This in vitro study characterized and monitored, by Optical Coherence Tomography (OCT) and Fourier Transformed Infrared Spectroscopy (FTIR), the effects of the association of acidulated phosphate fluoride gel (APF-gel) and Nd:YAG (neodymiun:yttrium-aluminum-garnet) laser, as sequencial treatments, in the prevention of incipient enamel caries lesions. Methods 120 human enamel samples were randomized into 3 groups (n = 40): APF-gel (1.23% F-, 4 min.); Laser+APF (Nd:YAG laser irradiation—0.6W, 84.9J/cm2, 10Hz, followed by APF-gel); and APF+Laser (APF-gel followed by laser irradiation). The samples were subjected to a 15-day pH-cycling, evaluated by OCT (quantification of optical attenuation coefficient–OAC) and FTIR (analysis of carbonate and phosphate content) before treatments, after treatments, and on the 5th, 10th and 15th days of pH-cycling. The statistical analysis was performed (α = 5%). Results The Optical Attenuation Coefficient (OAC) assessed by OCT increases with the progression of demineralization, and the Laser+APF presented the highest values of OAC in 10th and 15th days of pH-cycling. Nd:YAG decreased the carbonate content after treatment regardless of the application order of the APF-gel, while APF-gel did not interfere in the composition of enamel. The carbonate content was also changed in the first 5 days of the pH-cycling in all groups. Conclusion Nd:YAG laser irradiation before or after the application of APF-gel did not influence the appearance of incipient caries lesions, showing no synergistic effect. Regardless of the application order of the APF-gel, laser irradiation reduces the carbonate content of the enamel, which also changes during the demineralization process. However, irradiation before the application of APF-gel increased the speed of progression of the lesions, which positively impacts public health as it can prevent caries disease, even in high risk individuals. OCT and FTIR are suitable for assessing this effect.