Effect of diphenyliodonium hexafluorphosphate on resin cements containing different concentrations of ethyl 4-(dimethylamino)benzoate and 2-(dimethylamino)ethyl methacrylate as co-initiators

• Both amines (EDAB and DMAEMA) can be used combined with DPI in resin formulations.
• Resin cements using DMAEMA as co-initiator has the properties improved by use of DPI.
• EDAB seems to be the best amine to be used in resin cements with or without DPI.

ObjectiveThe present study evaluated the influence of diphenyliodonium hexafluorphosphate (DPI) combined with two different amines [ethyl 4-(dimethylamino)benzoate (EDAB) and 2-(dimethylamino)ethyl methacrylate (DMAEMA)] on the properties of model resin cements.MethodsA comonomer base containing a 1:1 mass ratio of 2.2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) was obtained, after which 1 mol% of camphorquinone and 0.1 mol% of hydroxyl butyl toluene were added to the comonomer blend. Concentrations of co-initiators varied at 0, 0.5 or 1 mol% for DPI and in 1 or 2 mol% for amines (DMAEMA or EDAB). Silanated Ba-Al-Si glass (60 wt%) was added as filler. The combination of each amine and DPI concentration resulted in 12 formulations, which had the following properties analyzed: degree of conversion (DC), water sorption (Wsp) and solubility (Wsl), flexural strength (FS) and flexural modulus (Ef). Data for DC, FS and Ef were analyzed by two-way ANOVA and Tukey's test (α = 0.05) and Wsp and Wsl by Kruskal–Wallis and Dunn tests (α = 0.05).ResultsEDAB promoted a higher DC than did DMAEMA; however, DPI increased DC for all materials with DMAEMA. The physical properties of resin formulations containing EDAB were significantly better than those of groups with DMAEMA; however, DPI had a positive influence on the chemical and physical properties of the model resin cement containing DMAEMA, especially with higher concentrations of amine.SignificanceEDAB proved to be more reactive than DMAEMA, being less influenced by DPI. Resins containing a 1:2 CQ/amine ratio had better properties than those with 1:1.