The Effect of Thermo-cycling on Macro Shear Bond Strength of Bulk Fill and Incremental Resin Composite Using Two Different Bonding Systems

Objective: This study was carried out to assess the effect of self-etch vs etch & rinse dental adhesives and thermocycling on the shear bond strength (SBS) of bulk and incremental resin composite. Materials and Methods: A total of forty sound extracted human molars were used in current study and were equally divided into two main groups (20 each) according to filling technique; bulk and incremental technique. Each group was subdivided into 2 subgroups (10 each) according to bonding systems. Each subgroup was divided into two divisions (5 each) according to thermo-cycling. Results: There was no statistically significant difference between shear bond strength of the two resin composite technique with etch and rinse bonding system as regards non-thermo-cycled specimens. Similarly, with thermo-cycled specimens; there was no statistically significant difference between shear bond strength of the two resin composite technique. The bulk fill resin composite showed statistically significantly higher shear bond strength than incremental resin composite with self-etch bonding system and non-thermocycled specimens. While with thermocycled specimens; there was no statistically significant difference between shear bond strength of the two resin composite technique. Conclusion Thermocycling has no significant effect on shear bond strength values for the two adhesive systems tested. In bulk filled composite, thermocyling decreased the bond strength of the etch & rinse adhesive. Higher bond strength values were observed in two step self etch adhesives in comparison to non-thermocycled etch & rinse adhesives.