Effect of Erosion / Remineralisation Challenges on Microtensile Bond Strength of two Dentin Adhesives

Objectives: To investigate the effect of erosion / remineralisation challenges on microtensile bond strength (mTBS) of two dentin adhesives (Optibond FL, Futurabond M) in vitro. Material and Methods: 150 extracted third molars were included. The specimens were randomly assigned to one of the five challenges of thirty samples each: G-1: control; groups G-2/-3: 10-minute immersion 4x/day in Sprite Zero for 7 days; G-4/-5: 5-minute immersion 6x/day in citric acid for 10 days. In G-3/G-5 the first and the last erosive challenge was followed by 2-minute remineralisation challenge in elmex EROSION PROTECTION dental rinse. Between the erosive/remineralisation challenges, the specimens were immersed in artificial saliva. Subsequently, the dentin specimens were restored with either Optibond/Grandio (O) or Futurabond/Grandio (F). Results: Following mTBS were evaluated (in MPa): G1-O: 25.46 (±5.02); G2-O: 18.59 (± 4.77), G3-O: 22.94 (± 3.87), G4-O: 11.02 (±2.62); G5-O: 16.00 (±3.53); G1-F: 20.91 (±4.53); G2-F: 15.20 (±3.62); G3-F: 17.04 (± 5.32); G4-F: 5.05 (±1.03); G5-F: 11.71 (±2.24). Statistical analysis showed a significant influence of the used adhesive and the challenge on mTBS (p0.001, ANOVA). Erosive challenges resulted in a significant reduction of mTBS compared to the untreated controls. Remineralisation with elmex dental rinse increased mTBS significantly in G-5 compared to G-4 (p0.05, Tukey's test). Conclusions: Erosion affected the mTBS of both adhesives in vitro. Remineralisation with elmex dental rinse might be a solution to increase mTBS of adhesives on eroded dentin. Clinical relevance: Adhesive fillings are commonly used to restore eroded dentin. Keywords: erosion, remineralisation, microtensile bond strength, dentin adhesives