Effect of surface treatment on glass ionomers in sandwich restorations: a systematic review and meta-analysis of laboratory studies.

Objectives: This study aimed to evaluate the effect of different surface treatments on the bond strength between new or aged glass ionomers (GI) and resin composites in sandwich restorations.

Methods: A comprehensive search was conducted in three databases to identify studies focusing on the bond strength of new or aged GIs and resin composites in laboratory settings. The selected studies were assessed for potential biases based on predetermined criteria. Additionally, a meta-analysis was performed using three studies.

Results: A total of 29 studies were included, with 24 investigating the bond strength of new GIs and five focusing on GI repair. Three studies were included in the meta-analysis (with a 95% confidence interval) which revealed no significant difference in the mean MPa values of resin-modified glass ionomer (RMGI) treated with phosphoric acid or Er,Cr:YSGG laser before the application of an etch-and-rinse adhesive. Surface treatment was found to be crucial for achieving optimal bonding between GI and resin composite, regardless of the GI's condition.

Conclusions: The combination of mechanical and chemical surface treatments does not significantly affect the bond strength between new RMGI and composite. However, for GI repair, it is recommended to use both treatments to enhance the bond strength.