Bond Strength of Silorane and Methacrylate-BasedComposites to Resin-Modified Glass-Ionomers

Objectives: This study evaluated the shear-bond strength of a resin-modified glass-ionomer (RMGI) restorative material (Fuji II LC, GC) to a new silorane-based composite (Filtek LS, 3M/ESPE) and a methacrylate-based composite (Filtek Z250, 3M/ESPE) in a sandwich technique with various combinations of surface treatments and bonding agents. 

 Methods:  The RMGI was bonded to Filtek LS or Z250 using the silorane-based (Filtek LS System Adhesive (LSA), 3M/ESPE) or methacrylate-based (Clearfil SE (CSE), Kuraray) self-etch adhesive systems.  Molds were filled with the RMGI and the surface was prepared in one of four ways: no treatment, etched with phosphoric acid, bur-roughened, or both bur-roughened and etched.  Either the LSA or CSE adhesive system was applied according to the manufacturer’s instructions.  Next, either Filtek LS or Z250 was bonded to the RMGI, creating 16 groups of 10 specimens each.  Specimens were stored for 24 hours in 37°C 100% humidity and tested in shear (Instron).  A mean and standard deviation was determined per group.  A three-way ANOVA was used to evaluate the effect of surface preparation (4 levels) and bonding agent (2 levels) on the shear-bond strength of composite (2 levels) to RMGI (alpha=0.05). 

Results: A significant difference in bond strength was found based on composite (p<0.001) and bonding agent (p<0.001) but not on surface treatment (p=0.699) with no significant interactions (p>0.05). 

Conclusions:  Surface modifications did not affect the shear-bond strength of the silorane or methacrylate composites to the RMGI.  The new silorane composite (Filtek LS) had significantly lower bond strength to the RMGI compared to the methacrylate composite (Filtek Z250).  The new silorane adhesive agent (Filtek LS System Adhesive) had significantly higher bond strength to the RMGI compared to the methacrylate adhesive agent (Clearfil SE). The greatest bond strengths to the RMGI were produced when using the silorane adhesive agent with the methacrylate composite.

 

Resin Composite	Bonding Agent	Mean Shear Bond Strength MPa (st dev)
		No modification	Etch only	Bur only	Bur and etch
Filtek LS	LSA	10.11 (5.68)	8.82 (5.43)	10.23 (4.41)	12.05 (2.46)
	CSE	4.13 (4.15)	6.89 (5.65)	7.23 (5.32)	4.09 (3.17)
Filtek Z250	LSA	18.13 (5.80)	15.56 (5.63)	14.71 (4.40)	15.68 (4.08)
	CSE	15.36 (2.26)	12.84 (2.59)	11.22 (2.93)	12.52 (4.15)