Shear Bond Strength of RMGI Cements Following Four Surface Treatments

Objective: To evaluate the effect of four surface treatments on the shear bond strength of three resin modified glass ionomer (RMGI) cements to dentin. Method: One hundred and twenty caries free third molars were mounted in acrylic resin and their occlusal surfaces reduced to within 2mm of their CEJ. The three RMGIs were: FujiCem (F), Rely-X Plus (R) and Infinity (I). The four surface treatments were: no treatment (N), 20% polyacrylic acid for 10 seconds (P), solution of 10% citric acid and 2% ferric chloride for 10 seconds (C), and Optibond Solo Plus with BondLink (O). Titanium cylinders 3mm in diameter and 5mm in length were air abraded, tin plated and cemented to dentin in 12 different possible combinations of surface treatments and cements (n=10). Specimens were stored in de-ionized water for 72 hours at 37 degrees Celsius prior to shear testing in an Instron Universal Testing Machine at a crosshead speed of 0.02inches/min. Results: mean bond strengths and S.D. recorded in MPa were as follows: FN 4.4(1.3)^b, FC 8.3(5.7)^ab, FP 0.3 (.44)^e, FO 19 (5.1)^ab, RN 8.4 (2.9)^ab, RC 10.3 (4.9)^ab, RP 1.1 (2.1)^d, RO 22.7 (5.2)^a, IN 3.0 (.82)^bc, IC 7.2 (4.6)^ab, IP 2.6 (4.7)^cd, IO 9.7 (3.4)^ab. Conclusion: A two way ANOVA and Tukey's test p<0.05 indicated differences in treatments were not consistent across cements, and differences among cements were not consistent across treatments. Rely-X Plus and FujiCem when used with Optibond Solo and BondLink produced the highest bond strengths. Citric acid and ferric chloride increased bond strengths compared to no treatment, but not significantly. Weakest bond strengths were produce using polyacrylic acid. Groups with same letters are not significantly different p<0.05.