Effect of addition of fluorescent agent (Rodhamine B) to no-simplified dentin bonding agents: analisys of physical-mechanical properties

Abstract

Rhodamine B is a fluorescent dye commonly used in dentistry for assessing several aspects of adhesive restorations via confocal laser scanning microscopy. By adding rhodamine in adhesive systems, it is possible to appraise characteristics of resin components distribution throughout previously demineralized dentin (the hybrid layer micromorphology, extent and amount of resin tags and adhesive layer thickness) as well as detecting potential defects or changes in adhesive interface. However, dental field literature reveals lack of methodological agreement on dye preparations in bonding systems. The current study intends to estimate the serviceable rhodamine B concentration in simplified bonding systems regarded as gold standard in their categories: Adper" Scotchbond" Multi-Purpose (MP) - a three-step etch-and-rinse - and Clearfil" SE Bond (SE) - a two-step self-etching, in order to not interfere in their properties. Thus, the validation of this method will be measured by means of different physical-mechanical properties: bonding strength up to 1 year, sorption and solubility, degree of conversion and surface microhardness after application to dentin. This study will be divided in stages. Stage A - Determination of the proportion between rhodamine B mass and adhesive volume, according to each adhesive system under evaluation, since it is enough for full viewing the dye in specimens via confocal microscopic. Stage B - According to the predetermined concentration in the previous stage, the bond strength will be evaluated for each adhesive to dentin in specimens prepared for micro-tensile bond test up to 1 year. The mode failure of fractured specimens will be qualitatively analyzed uneder optical microscopes (x40). Stage C -Sorption and solubility of the pure and mixed bonding systems, subjecting them to cycling and desiccation. Stage D- Degree of conversion of the pure bonding systems and respectives mixed with predetermined concentration of rodhamine. Stage E- Surface microhardness analysis after application of pure bonding systems and respectives mixed with predetermined concentration of rodhamine on dentin. Data from different tests will be assessed according to a normal distribution. If this condition will be satisfied, the control groups (without rodhamine) and respective experimental grous will be compared by t-test and analysis of variance (ANOVA). Significance level of 5% will be considered. (AU)