Effect of ethanol-dissolved rhodamine B marker on mechanical properties of non-simplified adhesives

Rhodamine B (RB) is commonly used to evaluate dental polymers, including dental bonding systems (DBS). For reliability assessments, its effect should not only allow visualization of the dentin-polymer interface but also must not interfere with the bonding of the DBS to dentin as measured by the microtensile bond strength and hardness tests.Flat human dentin surfaces were prepared and randomly distributed (n = 10) into six groups: Adper Scotchbond Multi-Purpose (MP) or Clearfil SE Bond (SE) in concentrations of none/control, 0.02 or 0.1 mg/mL. These combinations were prepared through ethanol dissolution to improve their penetration into the dentin. All specimens were fabricated with Filtek Z250 (n = 10) and prepared for a microtensile bond test (μTBS) (0.5 mm/min) after 7 days and 6 months. The failure modes were determined using a stereomicroscope (×40). For the hardness test, flat human dentin blocks were prepared and treated as previously described (n = 6). The specimens were stored at 37 °C/48 h and were tested (Knoop indenter - 25 gF/10 s). Data were analyzed with two-way ANOVA and Tukey tests for multiple comparisons (α = 0.05). The effect of time was evaluated using the Student t-test.For 7-day μTBS, both the DBS and RB concentrations were significant factors (p 0.01). After 6 months, only the RB concentration was significantly different. Adhesive failures were prevalent for all groups. Regarding hardness, the DBS differed only with the use of 0.10 mg/mL of RB.Ethanol-dissolved rhodamine B in concentrations of 0.02 and 0.10 mg/mL in non-simplified adhesives can affect the physical-mechanical properties of functional monomer-based systems rather more than those of BisGMA systems.