Ação do trimetafosfato de sódio sobre a hidroxiapatita durante ciclagem de pH: análise bioquímica, por espectrometria de infravermelho e difração de raios-x

• Autor(a) principal: Souza, José Antonio Santos [UNESP]
• Data de Publicação: 2011
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155144; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-02-24/000879415.pdf
• topic: Durapatita; Desmineralização do dente; Fluoretos; Durapatite

Studies have shown that sodium trimetaphosphate (TMP) has a preventive effect in dental enamel demineralization when associated with low fluoride (F) concentrations, but the mechanisms by which TMP acts in enamel is still uncertain. The aim of this study was to analyze the effect of TMP and/or F in hydroxyapatite (HA). HA was prepared by precipitation (calcium nitrate and ammonium phosphate) and matured during 7 days (37 ºC). The precipitate was separated by filtration, dried (70 ºC) and ground to obtain particles between 75 and 53 μm in diameter. Synthetic HA (n=5) was suspended in TMP solutions (100 mL) and divided into the following groups: placebo (deionizer water), 500 (500 μg F/mL), 1,100 (1,100 μg F/mL), TMP 1%, TMP 3%, 500 TMP 1% and 500 TMP 3%. The pH-cycling regimen was repeated 3 times, by lowering the solution's pH to 4.0 and, after 30 minutes, rising to pH 7.0 (37 ºC). After 24 of maturation, the precipitate was dried at 70 ºC for 24 hours, ground into a fine powder (53 μm in diameter) and characterized by Fourier Transformed Infrared Spectroscopy (FTIR) and X-ray Diffraction (DRX), as well as F, calcium (Ca) and phosphorous (P) analyses. Data was submitted to ANOVA, followed by Bonferroni's test (p<0,05). Results of DRX showed more defined peaks for the group 1,100, when compared to the others. The association of F (500 μg F/mL) with TMP at 1 or 3% resulted in more defined peaks when compared to HA prepared (HAp), TMP 1% and TMP 3%. FTIR analysis showed phosphate bands with higher intensity for the fluoridated groups when compared with the placebo. Peaks were less pronounced in the groups 1,100 and 500 TMP 1%. The association of TMP 1% or 3% to 500 μg F/mL solution increased CaF2 formation 4 and 2-fold, respectively when compared to groups 500 and 1,100 (p<0,05). Groups 1,100, 500 TMP 1% and 500 TMP 3% presented Ca/P molar ratios closer to pure HA. It was concluded that...