Abstract
It is reported that methacrylates with both hydrophobic and hydrophilic groups promote the interpenetration of monomers into tooth substrates. 2-Hydroxy-3-phenoxypropyl methacrylate (HPPM) and 2-hydroxy-3-β-naphthoxypropyl methacrylate (HNPM) were only effective for adhesion to etched enamel. The bond strength was 18MPa when 5% 4-methacryloxyethyl trimellitate anhydride (4-META) in MMA, initiated by tri-n-butyl borane (4-META/MMA-TBB resin), was applied to dentin treated with 10% citric acid and 3% ferric chloride (10-3). The 10-3 solution did not have any adverse effects on the higher order structure of dentinal collagen during demineralization. It has been found that the adhesion promoting monomers, HPPM, HNPM and 4-META, are effective at increasing bond strength to dentin and enamel, and that there is a strong relationship between interpenetration and the bond strength. The affinity of HPPM and HNPM for hard tissues was weaker than that of 4-META and they could not promote monomer interpenetration deeply enough into the intact dentin. SEM observations of dentin side tensile fracture specimens showed cohesive failure of the demineralized dentinal region.
