The self-etch concept has been increasingly adopted for bonding procedures, mainly as an attempt to reduce technique sensitivity. The reported lower bonding effectiveness for resin composites may be overcome by an additional conditioning step, particularly in enamel. Objectives: To evaluate an experimental self-etch adhesive (SEA) for resin-modified glass ionomers (RMGI's) and investigate the effect of a previous conditioning step. Methods: The micro-tensile bond strength (µTBS) to enamel and dentin of a RMGI restorative material (Fuji II LC, GC), and a RMGI adhesive (Fujibond LC, GC) bonded to a resin composite (Gradia Direct CV, GC), was determined for 4 different surface pre-treatments: no conditioning (NC); 25% polyalkenoic acid (Cavity C, GC) for 10 s (CC); an experimental SEA (OP7, GC) for 10 s (OP7); and 37.5% phosphoric acid (Kerr Etchant, Kerr) for 15 s followed by OP7 (H₃PO₄/OP7). Additional enamel and dentin interfaces were prepared for ultrastructural analysis with TEM. Results:

µTBS (MPa)	NC	CC	OP7	H3PO4/OP7
Enamel Fuji II LC	20.6(12.4)a# n=12	39.6(13.6)b,c n=12	34.8(12.3)b n=12	57.3(16.2)c n=11
Enamel Fujibond LC	9.8(7.1)A* n=11	35.7(4.0)B n=11	35.8(9.8)B n=12	42.4(11.9)B n=12
Dentin Fuji II LC	33.2(7.8)x n=12	35.1(10.7)x,y n=12	39.4(9.6)x,y n=12	46.2(8.6)y n=11
Dentin Fujibond LC	11.1(9.3)X+ n=11	27.7(10.1)Y n=15	29.6(7.8)Y n=12	36.2(10.2)Y n=12

^*: 1 pre-testing failure (ptf); ^#: 2 ptf's; ⁺: 4 ptf's; ptf's were considered as 0 MPa; different superscript letters indicate significant difference (Kruskal-Wallis test, p<0.05).

Interfacial analysis showed the formation of a thin hydroxyapatite-containing hybrid layer when the SEA was used. Conclusions: The use of a SEA increased the bond strength of RMGI's, especially in dentin. After an additional conditioning step, there was a further increase in bond strength, especially in enamel. This study was partially supported by CAPES Foundation.

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