THAIS FREITAS RABELO
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Resumo IPEN-doc 27990 Er,Cr:YSGG laser irradiation associated to fluoride for in situ model using gamma sterilized dentin and enamel2019 - ZAMATARO, CLAUDIA B.; RABELO, THAIS F.; ZANINI, NATHALIA; JUVINO, AMANDA C.; KUCHAR, NIELSEN G.; CASTRO, PEDRO A.L.; ANA, PATRICIA A. da; ZEZELL, DENISE M.The in situ intraoral model uses human dental enamel samples (HDE) in order to analyse the de-remineralization processes using the buccal environment without interfering into the patients’ natural dentition. The main ethical concern from this model is the biosafety. Gamma radiation is a very efficient sterilization method that is not expected to alter the mineral content of the hard tissues, avoiding biases in the results. Thus 40 HDE samples were irradiated through a source of 60Co multipurpose irradiator aiming complete sterilization (25 KGy/h) with the purpose of accumulating the native plaque on them at an in situ study. An Er,Cr:YSGG laser was used alone and in combination with the topical applications of: 1-dentifrice (1,100 lg F-/g) or 2-APF (12,300 lg F-/g). Morphological analyses were performed by scanning electron microscopy (SEM), determination of alkali-soluble fluoride concentration by specific ion electrode and microhardness determination. Then, the 15 volunteers used palatal devices containing previously treated HDE samples and remained using F dentifrice. The FTIR findings established that gamma radiation could be used aiming HDE sterilization. The Knoop hardness number was within the range of that of natural dentin of human origin. X-ray fluorescence shows that irradiated dentin has great similarity with natural dentin from the point of view of chemical composition. SEM analyses showed that there was no thermal damage or interprismatic morphological changes in the hydroxyapatite structure of human dental dentin outside the buccal environment when using doses of gamma irradiation up to 25 kGy.Resumo IPEN-doc 27989 In vitro determination of the critical pH demineralization of human dental enamel irradiated with Nd:YAG laser associated with fluoridated product2019 - JUVINO, AMANDA C.; ZAMATARO, CLAUDIA B.; RABELO, THAIS F.; KUCHAR, NIELSEN G.; ZANINI, NATHALIA; CASTRO, PEDRO; ZEZELL, DENISEThe use of fluoride products associated with high intensity laser irradiation are beneficial for dental caries prevention because it increases the surface area, improving the formation of fluorapatite (FA), which gives greater acid-resistance of enamel against bacterial acids. The objective of this study is to determine the critical pH of dental enamel treated with acid fluoride phosphate 12,300 lF-/g (APF) and Nd:YAG laser 84 J/cm2, as there is no precedent to determine this pH. The study consisted of 4 groups (n = 15): G1: Negative Control; G2: APF; G3: Nd:YAG; G4: APF + Nd:YAG. Each group was randomized into three subgroups (n = 5) for pH cycling. The cycling was designed to simulate three conditions: below critical pH of enamel hydroxyapatite (pH 5.0); pH below critical for hydroxyapatite and fluorapatite (pH 4.5); condition further below the critical situation to investigate extent of acid resistance of the enamel (pH 4.0). The samples were analyzed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR) and solutions were quantified fluoride (specific ion electrode) and phosphate (colorimetric method). In SEM and FTIR (phosphate band) at pH 5, only the APF and APF + Nd:YAG groups did not present demineralization. At pH 4.5, only the APF + Nd:YAG group was integrated. At pH 4, APF + Nd:YAG showed signs of mild demineralization while the other groups showed aggressive signals. It is concluded that the irradiated fluorapatite has critical dissolution pH different from fluorapatite formed only with the application of fluorine.Artigo IPEN-doc 27710 Morphological, optical, and elemental analysis of dental enamel after debonding laminate veneer with Er,Cr:YSGG laser2021 - ZANINI, NATHALIA A.; RABELO, THAIS F.; ZAMATARO, CLAUDIA B.; CARAMEL-JUVINO, AMANDA; ANA, PATRICIA A.; ZEZELL, DENISE M.Laminate veneer removal is becoming a routine procedure at the dental clinic and the use of laser can facilitate its removal. This work aimed to evaluate the morphological, elemental, and optical changes in the remaining enamel after veneer removal using Er,Cr:YSGG laser. Forty‐four enamel slabs were prepared and randomly distributed into nine experimental groups, for bonding using lithium disilicate laminates with three different luting agents (Variolink Veneer, RelyX U200, and RelyX Veneer). Then each agent was debonded using Er,Cr:YSGG laser (2.78 μm) using two different protocols:3.5 W, 48.14 J/cm2, 20 Hz non‐contact and 3.0 W, 48.14 J/cm2, 20 Hz non‐contact. The morphological, optical, and elemental analysis of enamel was performed before cementation and after laser debonding, using scanning electron microscopy (SEM), optical coherence tomography (OCT), and energy‐dispersive X‐ray spectroscopy (EDS). The level of statistical significance adopted was 5%. The EDS analysis of enamel after debonding revealed a significant increase in silane and carbon, as well as a decrease in calcium and phosphate contents. Analysis showed the presence of residual cement in most experimental groups but the morphological analysis showed alteration of the enamel's prisms only in the groups that used RelyX Veneer and Variolink Veneer cements. There was no evidence of deleterious morphological changes resulting from irradiation. However, an increase in the optical attenuation coefficient by the OCT was observed due to the presence of the remaining cement. It can be concluded that the Er,Cr:YSGG laser, in the mean powers used, is efficient for veneer removal without causing deleterious effects for the enamel.Resumo IPEN-doc 27533 Análise in vitro dos efeitos da radiação ionizante sobre o esmalte dental, cimento resinoso e facetas laminadas de porcelana2020 - RABELO, THAIS F.; ZEZELL, DENISE MARIAArtigo IPEN-doc 27155 Human dental enamel evaluation after radiotherapy simulation and laminates debonding with Er,Cr:YSGG using SEM and EDS2019 - RABELO, THAIS F.; ZAMATARO, CLAUDIA B.; KUCHAR, NIELSEN G.; ZANINI, NATHALIA; JUVINO, AMANDA C.; DEL-VALLE, MATHEUS; CASTRO, PEDRO A.A.; SANTOS, MOISES O.; ZEZELL, DENISE M.The pursuit of perfection makes younger people undergo aesthetic procedures without formal indication. However, young patients may be susceptible to a disease such as head and neck cancer which treatment can compromise the adhesion of these indirect mate-rials. Here, we present an analyze, of the gamma radiation effects on crystallographic morphology of human dental enamel after laminate veneer debonding with Er,Cr:YSGG laser. Thus, human dental enamel samples were prepared and randomized into 2 groups (n=10): Laser Irradiation (L) and Gamma + Laser Irradiation (GL) group. Scanning elec-tron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were performed before bonding and after debonding using Er,Cr:YSGG. Only Gamma + Laser Irradia-tion group received a cumulative dose of 70 Gy gamma radiation used in head and neck cancer radiotherapy. SEM images showed that both GL and L groups presented altered morphology. EDS showed an decrease in Ca and P intensities after laser debonding of laminates veneers in both group. Therefore, a proper laser facet removal protocol should be established for healthy patients and patients who have been exposed to radiotherapy for head and neck cancer.Artigo IPEN-doc 26236 Effect of Er,Cr:YSSG laser on dental Veneers removal submitted to gamma radiation2019 - ZANINI, NATHALIA; RABELO, THAIS F.; ZAMATARO, CLAUDIA B.; JUVINO, AMANDA C.; KUCHAR, NIELSEN G.; CASTRO, PEDRO A.A. de; ANA, PATRICIA A. da; ZEZELL, DENISE M.The search for aesthetical rehabilitive treatment such as porcelain veneers is increasing over the past years. After CEP-FOUSP approval, the present study investigated the debonding of 20 ceramic fragments of lithium disilicate(5x5x1 mm) from human dental enamel bond with Variolink ® N. The samples were splitted in two groups: control (without gamma irradiation) and treatment (gamma irradiation: GL). EDS and FTIR was performed on enamel in both groups, before and after treatment. After cementation of the ceramic fragments the control group was only irradiated with Er, Cr: YSGG laser (λ = 2.78 nm) to remove the fragments, whereas the GL was gamma irradiated with 0.07 kGy followed by laser irradiation Er, Cr: YSGG for removal of laminates.The laser parameters were previously determined as follows: 3.5 W. The gamma and laser (GL) group was exposed to gamma radiation and the erbium laser was applied in both groups to remove lithium disilicate laminates from human dental enamel. Thus, the load required to remove the laminates after simulation of the radiotherapy treatment in the human dental enamel was analyzed by mechanical assay. In this assay, the GL group presented higher loads for the removal of the laminates compared to the control group. This indicates that the gamma radiation induces a water radiolysis by modifying the hybrid layer of the adhesive cement and increases the bond between the enamel and the resin cement, which hinders the laser debonding of the laminates.Artigo IPEN-doc 26235 FTIR analysis of human dentin submitted to gamma radiation2019 - KUCHAR, NIELSEN G.; ZAMATARO, CLAUDIA B.; CASTRO, PEDRO A.A. de; RABELO, THAIS F.; JUVINO, AMANDA C.; ZANINI, NATHALIA; ZEZELL, DENISE M.Global data indicate that head and neck cancer express one of the sixth most common types of malignant cancers. In 2030, head and neck cancer predict 1,031,439 new cases per year around the world. Radiation therapy is used as a major therapy step in the treatment protocol for head and neck malignancies. Radiation caries consists in a side effect of xerostomia, ie a considerable reduction in the quantity and quality of saliva in the oral cavity, being defined as a type of cavity that advance severely with fast progression being able to injure the dental pulp. Gamma radiation effects can promote changes associated to modification in the enamel prismatic structure, the reduction in surface microhardness and biochemically alterations in the tooth composition. However, other studies where the human dental enamel using ionizing radiation present no differences found in the integrity of the dental enamel and there was no interference in the surface microhardness. In this study, 20 human dentin samples were evaluated, split randomly into the control group and irradiated group at 25 kGy, in the Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The FTIR shows that no significant changes were found in the Phosphate band representing the inorganic material. On the other hand, the Amide I band -chosen as the representative of the organic matrix composed mainly of collagen- showed a significant difference, suggesting a degradation of the organic content. These findings corroborate with SEM analysis after the gamma irradiation dose at 25 kGy.