This study examined the bonding abilities to enamel and dentin substrates and the flexural properties of five resin-modified glass-ionomer luting cements [RMGICs: Fuji Luting EX and Fuji Luting S (GC), RelyX Luting Plus Automix and Vitremer Paste (3M ESPE), ResiGlass Paste (Shofu)], as compared to those of one resin cement [SA Luting (Kuraray Noritake Dental)]. The following properties were evaluated: shear bond strength to human enamel and dentin, and flexural properties (flexural strength and flexural modulus) of cements immediately after setting, after one-hour storage, and after one-day storage, together with flexural properties (flexural strength and flexural modulus). The shear bond strengths of RMGICs and the resin cement to tooth substrate (enamel and dentin) after onehour storage were significantly higher than those immediately after setting, and those of RMGICs to tooth substrate after one-day storage were significantly higher than those after one-hour storage. The flexural properties of RMGICs demonstrated similar tendencies to those of the shear bond strength to tooth substrate. However, the flexural properties of resin cement were significantly better than those of RMGICs. There was a highly significant correlation between shear bond strength of RMGICs to tooth substrate and flexural properties of RMGICs.

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This study evaluated the dentin adaptation of resin composite restoration to cavities prepared with an Er,Cr:YSGG laser. Bowl-type cavities (3 mm in diameter, 2 mm deep) were prepared on the buccal and lingual surfaces of extracted human molars using an Er,Cr:YSGG laser (Waterlase MD, Groups 1 to 6) or an air-turbine handpiece (Control). Each cavity was treated with bonding agent (Mega Bond/Bond: MBB, Group 1); self-etching primer (Mega Bond/Primer: MBP) and MBB (Group 2 and Control); phosphoric acid (K-etchant Gel: KEG), MBP and MBB (Group 3); sodium hypochlorite (AD Gel: ADG), KEG, MBP and MBB (Group 4); all-in-one adhesive (tri-S Bond: TSB, Group 5); and ADG, KEG and TSB (Group 6) (n=10). After each bonding procedure, all cavities were restored with a resin composite. The specimens were subjected to thermal stresses consisting of 500 cycles between 5°C and 55°C. Each cavity was sectioned longitudinally using a diamond saw. The cut surfaces were dyed with a caries detector to visualize gap formation in the cavity. The ratio of dye penetration (%, means ± SD) in the dentin was 81.6 ± 13.9 for Group 1, 15.7 ± 11.4 for Group 2, 7.1 ± 9.9* for Group 3, 5.8 ± 8.0* for Group 4, 66.5 ± 18.8 for Group 5, 15.6 ± 16.1* for Group 6 and 1.4 ± 2.2* for the Control (*: p<0.05). Pre-conditioning using phosphoric acid and sodium hypochlorite effectively improved the cavity adaptation of resin composite in cavities prepared using the Er,Cr:YSGG laser.

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