Repair Bond Strength of High-viscosity Glass-ionomer Cements Using Resin Composite Bonded with Light- and Self-cured Adhesive Systems

Objectives: Despite the success rate of highviscosity glass-ionomer cements (HVGICs) used in atraumatic restorative treatment (ART) restorations, partial or bulk fracture of the proximal portion has been recorded to be one of the main causes of proximal restoration failures. Repair of these restorative materials requires a practical solution, especially in cases where there is a lack of electricity. Thus, the purpose of this study was to evaluate the repair microshear bond strength (mu SBS) of three HVGICs using a resin composite in association with adhesive systems having different curing modes (ie, light- vs self-curing mode). Methods and Materials: A total of 105 discs (12 mm in diameter and 2 mm thick) of three HVGICs: GC Fuji IX GP Fast (GC Corporation, Tokyo, Japan); Fuji IX GP glass-ionomer cement containing chlorhexidine (GC Corporation, Tokyo, Japan); and ChemFil Rock zinc-reinforced HVGIC (Dentsply De-Trey GmbH, Konstanz, Germany) were prepared. Each specimen was divided into three horizontal sections, according to the tested adhesive system or curing mode: Clearfil SE Bond 2 (two-step, self-etch adhesive); (Kuraray Noritake Dental Inc., Tokyo, Japan) in light-cure mode; Clearfil Universal Bond (one-step, self-etch adhesive); (Kuraray Noritake Dental Inc., Tokyo, Japan) in light-cure mode; or Clearfil Universal Bond (one-step, self-etch adhesive); (Kuraray Noritake Dental Inc., Tokyo, Japan) in selfcure mode, mixing it with Clearfil DC Activator (Kuraray Noritake Dental Inc., Tokyo, Japan). A resin composite microcylinder was bonded to each horizontal section of each specimen using starch tubes. The bonded discs were stored in artificial saliva at 37oC for 24 hours. A mu SBS test was conducted using a universal testing machine, while failure modes were determined using scanning electron microscopy. Data were statistically analyzed using two-way analysis of variance (ANOVA), one-way ANOVA, and Bonferroni post hoc tests (alpha=0.05). Results: Two-way ANOVA revealed a statistically significant effect for the adhesive systems (p<0.01) and not for the HVGICs (p=0.05) nor their interactions (p=0.99). When using Clearfil SE Bond 2 and Clearfil Universal in a light-cure mode, significantly higher mu SBS values were found when compared with Clearfil Universal in a self-cure mode. Conclusions: The three tested HVGICs can be successfully repaired using two-step or one-step self-etch adhesive systems. The one-step self-etch adhesive system in light-cure mode is preferred when compared with the self-cure mode.