Immediate and delayed micro shear bond strength evaluation of two glass ionomer cements to composite resin by using different bonding techniques-an in vitro study.

Objective: Evaluating immediate and delayed micro shear bond strength (µSBS) between composite resin and glass ionomer cements using different adhesive systems and mechanical surface treatment.

Materials and methods: A total of 240 specimens of glass ionomer restorative materials were divided into two groups: Resin Modified Glass Ionomer Cement (RMGIC) namely Riva Light Cure and Conventional Glass Ionomer Cement (CGIC) namely Riva Self Cure. These were subdivided into immediate (24 h) and delayed (3 months) storage and further divided into smooth, medium, and rough surface treatment with either total etch (TE) or self-etch (SE) adhesive strategies. Composite resin was applied and µSBS of the sample was determined and failure modes were examined.

Results: Immediate µSBS of RMGIC was superior than CGIC and TE was better than SE. Within RMGIC, smooth surface has significantly higher bond strength than medium and rough stone surface treatment. Delayed µSBS of RMGIC was superior than CGIC. Within RMGIC specimens, TE and smooth and medium grit had significantly better bond strength than SE and rough grit. Within CGIC, statistically higher bond strength values were found with medium grit compared to smooth while no difference was found between TE and SE.

Conclusion: Bonding composite resin to smooth RMGIC using TE yielded higher bond strength values than CGIC regardless of the time. Bonding composite resin immediately to CGIC is best done using a TE technique. However, delayed bonding to CGIC requires roughening of the CGIC surface prior to placement of the composite resin to obtain improved bonding.