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Validation of pH cycling model to estimate the potential of fluoridated products in reducing deciduous enamel demineralization

Grant number: 12/03105-5
Support type:Scholarships in Brazil - Master
Effective date (Start): July 01, 2012
Effective date (End): February 28, 2014
Field of knowledge:Health Sciences - Dentistry - Social and Preventive Dentistry
Principal Investigator:Cinthia Pereira Machado Tabchoury
Grantee:Marilia Mattar de Amoêdo Campos Velo
Home Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

The enamel of deciduous tooth has more carbonate in its composition and a thinner layer, so the carious lesion progression is faster than in the enamel of the permanent teeth. Thus, it is important that an in vitro model of pH cycling consider these differences and be validated against the dose-response effect of fluoride on tooth demineralization. The objective of this project is to validate an in vitro model of pH cycling for the study of the demineralization of the enamel of deciduous tooth, evaluating the dose-response effect to fluoride. Exfoliated healthy deciduous tooth (molars and incisors) will be used, which will be held in 2% formalin pH 7.0 for at least 30 days. Then, enamel blocks (3 x 3 x 2 mm), flat and polished only in the central area, will be obtained. The initial surface hardness of the specimens is determined for their selection and for calculating the surface hardness loss after pH cycling and treatments. For this, three indentations will be made in dental blocks and the selection criteria will be based on the average and standard deviation of the hardness of each block. This study will last for 10 days and, during the pH cycling, the dental blocks will be daily exposed to a demineralizing solution (2.0 mM calcium, 2.0 mM phosphate, 0.030 ppm F in 75 mM acetate buffer, pH 4.3) for 4 hours (6.25 mL/mm²) and the remineralizing solution (1.5 mM calcium, 0.9 mM phosphate, 150 mM KCl, 0.050 ppm F in 20 mM cacodylate buffer, pH 7.4) for 20 hours (3.12 mL/ mm²). Immersion of the dental blocks in the de and remineralizing solutions will be at 37ºC. In addition, the dental blocks will be submitted to the following treatments before and after immersion in the demineralizing solution: distilled deionized water (negative control); solutions containing 35, 70, 140, 280 and 560 ug F/ ml. At the end of the experiment, the surface hardness of all the blocks will be reassessed. The determination of the cross-sectional hardness of the enamel will also be done to assess the progression of carious lesions. De and remineralizing solutions will be assessed for the concentration of F. In addition, the firmly-bound fluoride (fluorapatite, FA) will be determined in the dental enamel blocks after acid extraction. This in vitro model of pH cycling will also be evaluated using commercially available toothpastes and the same tests previously described will also be conducted. The response variables will be submitted to exploratory statistical analysis, from which an appropriate test will be applied, considering the experimental model used. These analyzes will be a threshold of significance of 5%. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DE AMOEDO CAMPOS VELO, MARILIA MATTAR; MACHADO TABCHOURY, CINTHIA PEREIRA; ROMAO, DAYSE ANDRADE; CURY, JAIME APARECIDO. Evaluation of low fluoride toothpaste using primary enamel and a validated pH-cycling model. International Journal of Paediatric Dentistry, v. 26, n. 6, p. 439-447, NOV 2016. Web of Science Citations: 2.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.