Methods: Three GIC's 1-3 and two composites4,5 were fabricated into 1 x 10 mm diameter discs. These were exposed to either 10% carbamide peroxide (pH 7), 16.6% carbamide peroxide (pH 5.5) or 6% hydrogen peroxide (pH 5.5) in 0.1M phosphate buffer solutions (10 ml) for 1 hour at 25oC, in duplicate. For comparison disks were also exposed to solutions of water, phosphate buffer (pH 5.5 and 7.0), diet coke and 38% orthophosphoric acid (OPA). Concentration of the ions Al, Ba, Ca, Na, Si and Zn were measured in the various solutions by Inductively Coupled Optical Emission Spectroscopy (IC-OES). The increase in eluted ions as a result of exposure to the dental materials was calculated.
Results: For the GIC's, the 38% OPA solution showed a significant increase (t-test p< 0.05) in the release of Al (61-110 ppm) and Na ions (7-42 ppm) together with non-significant traces of Si (4-9ppm). All other test and comparison solutions showed no significant release of the ions measured. For the composite materials, there was no significant release of any ions for the test and comparison solutions. Conclusion: The carbamide peroxide and hydrogen peroxide solutions did not cause any significant ionic dissolution of the dental materials tested.
1ChemFlex, Dentsply, UK. 2Fuji II, GC Europe, Belgium; 3Ketac-Fil, 3M ESPE, Germany; 4Spectrum, Dentsply, UK; 5Z250, 3M ESPE, Germany