Effects of purified ferric oxalate/nitric acid solutions as a pretreatment for the NTG-GMA and PMDM bonding system

Abstract Nitric acid, found to be a contaminant left over from the synthesis of ferric oxalate, has been shown by this in vitro study to be responsible for the cleansing effect previously associated with ferric oxalate pretreatments. When 2.5% (w/w) nitric acid solution was substituted for ferric oxalate solution and then used in conjunction with the experimental dental bonding system of NTG-GMA (the adduct of N(p-totyl)glycine and glycidyl methacrylate) and PMDM (the adduct of pyromellitic acid dianhydride and 2-hydroxyethyl methacrylate), the result was strong adhesion of both dentin and enamel surfaces to Adaptic ® Dental Restorative. When a solution containing 3.4% (w/w) purified ferric oxalate was used with this system, the average bond strengths on both dentin and enamel decreased (p