Analysis of the effect of addition of Rhodamine B marker on mechanical properties of no-simplified dentin bonding systems

Abstract

Rhodamine B is a fluorescent dye that has been used in dentistry for assessing several aspects of adhesive restorations via confocal laser mainly associated with scanning microscopy. By adding rhodamine in adhesive systems, it is possible to appraise micromorphological characteristics of resin components distribution throughout previously demineralized dentin, as well as detecting potential defects or changes in adhesive interface. However, there is poor data of how this modification can influence bonding. The current study aims to evaluate the effect of addition of rhodamine B in two different concentrations: C1 (0.10 mg/ml) and C2 (lower concentration will be determined in a pilot study) in non-simplified bonding systems regarded as gold standard in their categories: Adper" Scotchbond" Multi-Purpose (MP) - etch-and-rinse three steps - and Clearfil" SE Bond (SE) - a self-etching two steps, considering the null hypotheses that there is no significant difference in tensile bond strength after addition of rhodamine B in two different concentrations and differente time, according to each adhesive system evaluated and difference in surface microhardness. For theses studies, the experiment will be divided into different stages: Stage A - Determination of the new proportion between rhodamine B mass and adhesive volume, according to each adhesive system under evaluation, since it provide adequate visualization of the dye in specimens via confocal microscopic, taking 0.10 mg/ml as reference value . Stage B - From two concentrations of rhodamine, the bond strength will be evaluated for each adhesive to dentin in specimens prepared for micro-tensile bond test after 7 days, 6 months and 12 months. The mode failure of fractured specimens will be qualitatively analyzed under optical microscopes (x40). Stage C - Surface microhardness analysis after application of pure bonding systems and respective mixed with predetermined concentration of rhodamine on dentin will be evaluated. Data from different tests will be statistically analyzed, with a significance level of 5%.