Effect of a buffered fluoridated solution on activation of dental enamel remineralization

• Grant number: 14/23783-3
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2015
• Effective date (End): February 29, 2016
• Field of knowledge: Health Sciences - Dentistry
• Principal researcher: Cinthia Pereira Machado Tabchoury
• Grantee: Larissa Daniela Orlando
• Home Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

The role of fluoride (F) in the prevention and control of dental caries is well described, as well as being the most relevant method, inhibiting demineralization and remineralization activating. Regarding the reactivity of F with the dental substrate, studies show that there are factors and substances that can interfere with this process. One of the main factors is the pH decrease, which leads to an increased reactivity of F. However, during the reaction of a solution with dental enamel a change in pH can occur, because as there is a reaction of phosphate and hydroxyl ions with protons of the solution, which would increase the pH of the solution, influencing the reactivity of F with dental enamel, decreasing it. The objective of this project is to evaluate, in a pH-cycling model, the reactivity of F present in a buffer solution at acid pH with dental enamel with artificial caries lesions. Enamel blocks (4x4x2 mm), obtained from bovine incisors and pre-selected from their surface hardness, will be used. The dental blocks will be randomized and subjected to the following test pH-cycling, which will last eight days. The blocks remain in the demineralizing solution (0.1 M acetate buffer pH 5.0, containing 1.28 mM Ca, 0.74 mM Pi and 0.03 M / ml) for 2 h and in the remineralization solution (Tris buffer solution 0.1 M pH 7.0 containing 1.5 mM Ca, 0.9 mM Pi, 150 mM KCl and 0.05 mg F / mL) for 22 h at 37°C (Queiroz et al. 2008). The dental blocks will be subjected to three treatment groups (n = 20): I - histidine solution containing 0.1 M pH 5.0 (negative control); II - solution containing 226 mg F / ml pH 5.0; III - solution containing 226 mg F / mL and histidine 0.1 M pH 5.0. The enamel blocks will react with the treatment solution 3 times a day (9, 14 and 17 h) in a 2 ml solution / mm² enamel surface exposed on a table shaker at 100 rpm at room temperature. The surface hardness will be determined again in the enamel blocks at the end of the pH-cycling, the percentage recovery of surface hardness (RDS%) will be calculated. Then, in half of the dental blocks the hardness of tooth enamel sectioned longitudinally will be determined. In the other half of the dental blocks, two successive layers of enamel will be removed by etching and firmly bound fluoride present in the acid extract will be determined by specific ion electrode to F. The study will be blinded for the operator. The data will be statistically analyzed.