Effect of mixing methods on the bonding strength of GIC

Objectives: The aim of this study was to evaluate the effect of the different mixing methods on tensile bond strength (TBS) of glass-ionomer-cement (GIC). This study evaluated TBS of GIC to bovine enamel (BE), bovine dentin (BD), and gold alloy (CASTWELL M.C. 12%GOLD:CW12 and CASTING GOLDM.C.TYPE III:CG3, GC) for prosthetic restoration.

Methods: The trial material FL-901 paste type GIC(GC) by hand-mix(FL-HM) and that by auto-mix(FL-AM) were evaluated. The latter were mixed by using the mixing tip. RelyX™ Luting Plus Cement(RXLP) paste type GIC(3M ESPE) in the clicker dispenser and RelyX™ Luting Cement(RXL) powder/liquid type GIC(3M ESPE), both were evaluated by hand-mix. All were mixed according to manufacturer's instructions. TBS test was carried out according to ISO/TS11405 (n=5). For the before thermocycled(TC0) specimens, TBS was measured (1mm/min) by an Autograph (SIMADZU) after 24hour at 37°C-100%RH. The other specimens were thermocycled (TC2000, 5/55°C) and followed by the measurement. The results were analyzed by three-way ANOVA and Turkey test.

Results: The mean values and S.D. were shown in the following table. There were no significant difference of TBS in the mixing methods and in among the different materials (p<0.01). However, there were significant difference in the factor of the substrate (p<0.01) and the thermocycle (p<0.05).

TBS:MPa	FL-HM(S.D.)		FL-HM(S.D.)		RXLP(S.D.)		RXL(S.D.)
	TC0	TC2000	TC0	TC2000	TC0	TC2000	TC0	TC2000
BE	10.0(±2.3)	8.2(±2.3)	9.2(±0.5)	10.2(±2.4)	11.9(±5.6)	12.7(±3.1)	9.8(±2.5)	8.9(±1.2)
BD	7.2(±1.4)	5.3(±1.4)	7.0(±0.8)	6.2(±1.6)	7.9(±1.4)	8.6(±3.2)	8.4(±2.3)	5.9(±1.5)
CW12	11.2(±2.7)	11.2(±5.0)	9.2(±2.9)	8.1(±0.8)	7.9(±2.0)	5.7(±0.7)	8.0(±1.4)	6.4(±1.7)
CG3	11.4(±2.0)	11.8(±2.5)	10.0(±2.6)	10.1(±1.5)	8.7(±1.2)	7.4(±2.0)	12.1(±2.3)	10.6(±1.2)

Conclusions: In this study, there was no significant difference of TBS in the mixing methods. Therefore, it is thought that auto-mix system demonstrates bonding stability like hand-mixing in clinical.