Comparison Of Cleaning Methods for Temporary Cement on Ni-Cr Alloy

Calcium hydroxide cement(Dycal) has used as one of temporary cement in Bridgework for short time before permanent cementation. Objective: To evaluate the effect of 5 methods (air abrasion with 1.Aluminum oxide, 2.glass bead, immersing in cement removal solution 3.RemovalonI, 4.L&R and 5.liquid of autopolymerized acrylic resin) for removing temporary cement(Dycal) on Ni-Cr alloy's surface to resin cement's bond strength. Methods: Casting Ni-Cr alloy cylinders (7 and 9 mm diameter, 3 mm height, 120 pairs each) were divided to 6 groups. The 20 pairs of each group of 5 methods were bonded with temporary cement excluding control group. After temporary cement were removed ,all pairs of casting were cemented with resin cement(Superbond C&B) and stored in water bath at 37°C for 24 hours. Shear bond strength were determined with a universal testing machine using a cross-head speed of 0.5 mm/minute. A 1-way ANOVA was performed, and multiple pairwise comparisons were completed with post hoc Tamhane test (alpha = 0.05). Results: Like a control group,The shear bond strength after using air abrasion with Aluminum oxide, Glass bead and immersing in cement removal solution L&R were significantly higher than after using RemovalonI and liquid of autopolymerized acrylic resin. Conclusion: In applications, air abrasion with 50 microns Aluminum oxide, Glass bead and using cement removal solution L&R offer simple, consistant, and effective methods to clean Dycal from Ni-Cr alloy, not effect to resin cement ‘s bond strength.