µTBS of New Resin-Modified Glass-Ionomer Cements: Effect of Dentin Pretreatment

Objective: to investigate whether the use of novel non-rinse conditioners (i.e., Ketac Nano Primer-3M ESPE and GC Self-Conditioner-GC America) as substrate pre-treatment and new paste/paste resin-modified glass-ionomer cement (RMGIC) (Ketac™ Nano 3M ESPE and Fuji Filling™ LC GC America) would affect microtensile dentin bond strength (µTBS) of the material compared to traditional RMGIC with polyacrylic acid as a surface substrate pre-treatment.

Method: Extracted non-restored human molars were sectioned to expose occlusal dentin. Dentin surface was finished to standardize the smear layer. Eight experimental groups were tested: G1-KetacNanoPrimer+KetacNano, G2-KetacConditioner+KetacNano, G3-KetacNanoPrimer+Photac Fil, G4-KetacConditioner+Photac Fil, G5-GCSelfConditioner+Fuji FillingLC, G6-GCCavityConditioner+FujiFillingLC, G7-GC Self Conditioner+FujiIILC and G8-GCCavityConditioner+FujiIILC. Specimens were stored at 37°C for 24h in 100% humidity before cutting non-trimmed beams (0.8×0.8mm²) for µTBS testing. Nine beams from each tooth were tested in a universal testing machine (1mm/min). Debonded specimens were examined under a stereomicroscope to evaluate failure mode. Weibull-distribution survival analysis was used to compare the differences in microtensile peak stress among the groups.

Result: Microtensile data is provided below (G6-pre-test failure). G5 demonstrated a cohesive failure mode, while failure for other groups was predominantly adhesive.

Groups	Teeth(N)	N Beams	Min	Max	Mean(SE)	Weibull Characteristic Strength	Weibull Modulus
1	10	84	0.2	33.8	9.5(1.0)	16.4	1.9
2	10	89	2.0	26.0	11.0(1.0)	19.3	2.3
3	12	106	1.4	42.1	20.0(1.0)	34.7	3.1
4	11	107	4.9	34.9	16.8(0.9)	29.3	3.0
5	12	98	1.7	28.7	15.1(1.0)	26.3	3.1
7	12	107	2.1	44.7	20.0(1.0)	34.7	3.5
8	12	99	0.8	36.0	14.1(0.9)	24.4	2.6

Conclusion: Within the limitations of this study, the use of the novel non-rinse conditioners did not improve the µTBS of new RMGIC to dentin. By contrast, the novel non-rinse conditioners enhanced µTBS of traditional RMGIC.

 Study partially supported by GC America.