EVALUATION OF SHEAR BOND STRENGTH OF COMPOSITE RESIN BONDED TO GLASS IONOMER CEMENT AND RESIN MODIFIED GLASS IONOMER CEMENT
The sandwich or laminate technique is recommended method for resin composite restorations. The bond between GIC or RMGIC and dental composite is main factor affecting retention, sealing and durability of the sandwich restorations.
This laboratory based experimental study compared and evaluated shear bond strength of composite resin bonded to conventional GICs and RMGICs using simple etch & rinse technique and with or without total etch adhesive.
The shear strength of conventional GICs (Fuji IX and Chemfil rock) and RMGICs (Fuji Plus and Fuji II LC) bonded to dental composite was investigated at 4 weeks. Thirty discs (10mm diameter x 2mm height) for each conventional GIC and RMGIC were fabricated by using polyvinyl siloxane (PVS) moulds. The discs of Fuji IX, Chemfil Rock and Fuji plus were self-cured (15 minutes) whereas discs of Fuji II LC were light cured (20 sec). These discs were inserted into cold cure acrylic resin in PVS moulds to form acrylic blocks. These blocks were wrapped in moist paper and put in 100 % humidified bags for 4 weeks at 37 °C. Total 120 cylinders of composites having diameter of 7mm and height of 5mm were prepared. The surfaces of GICs and RMGICs discs were initially treated with or without acid etching and acid etching plus adhesive before placement of composite cylinders. Shear bond strength of each sample was measured after 4 weeks via Instron machine (M 30 K) at 0.5mm/ min speed and load of 1 KN was used to fracture the sample. Means and standard deviations were calculated and t-test was used to analyse statistical differences.
Higher shear bond strength values for RMGICs with acid etchant plus bonding agent were observed as compared to GICs whereas GICs showed higher shear bond strength values with acid etchant alone. While RMGIC (Fuji II LC) showed low value with acid etchant alone and highest with the addition of bonding agent. But Fuji Plus showed a high value than both GICs with acid etchant alone.
The conclusion was that RMGICs bonded to composite with the use of both acid etchant and bonding adhesive had greater values of shear strength than GICs. While, GICs had higher bond strength values with acid etching only than Fuji II LC.