In Vitro Study Compared The Shear Bond Strength of HEMA-free and HEMA-containing Bonding Agents To Different Dentin Surface Treatments

This research was designed to investigate the effect of two dentin surface treatments on the shear bond strength of HEMA-free and HEMA containing bonding agent. A total of 90 freshly extracted, sound human molars, free from caries, extracted for pathological reasons was used in this study. The molars were randomly divided into two main equal groups (45 teeth each) according to the type of adhesive system; Group (A1) used HEMA-free adhesive (G-bond). Group (A2) used HEMA containing adhesive (One-up Bond F Plus). Each group was further subdivided into 3 equal subgroups
(15teeth each) according to the type of dentin surface treatments applied as follows: Subgroup (I) used the bonding agent only without surface treatment as a control [AB], Subgroup (II) used 10% Sodium hypochlorite followed by the bonding agent [AB1], Subgroup (III) used 10% Sodium hypochlorite then 10% Sodium ascorbate followed by the bonding agent [AB2]. Each subgroup was further divided into three groups of (5 teeth each) according to the storage times; 24 hours, three months, and six months. A Flat dentin surface was prepared, different surface treatments and adhesive systems were applied then Composite was bonded to the treated surfaces according to the manufacturer’s instructions and the shear bond strength testing was done using universal testing machine. The recorded values were tabulated and statistically analysed. The result of this study revealed that; the highest mean shear bond strength (18.39 +/- 2 MPa) was
recorded for those dentin specimens bonded to composite resin with HEMA-containing adhesive (One-up Bond F Plus) without surface treatment after 1 day storage time. While the lowest mean shear bond strength (10.7 +/- 1.6 MPa) was recorded for those dentin specimens bonded to composite resin with HEMA-free adhesive (G-bond) with sodium hypochlorite only after 6 months storage time. The results of this study revealed that 1- Sodium hypochlorite only has a significant adverse effect on the shear bond strength of both adhesives. 2- sodium hypochlorite followed by sodium ascorbate can render the adverse effect of sodium hypochlorite only on the shear bond strength of both adhesives.3- HEMA-containing adhesive (One-up Bond F Plus) without surface treatment showed better shear bond strength than HEMA-free adhesive (G-bond). 4-Storage in water for long periods has a highly significant adverse effect on the bond
strength especially of HEMA-containing adhesive.