Effect of Thermocycling on Bond Strength of Amalgam to Dentin

Objectives:  To evaluate the effect of thermocycling on several of the available amalgam bonding systems to determine which system would provide the best bond to dentin.

Methods: Four bonding agent systems were used. The bonding systems included AllBond 2 Primer A&B with Panavia 21 (Bisco and Kuraray), AllBond 2 Primer A&B with Prebond & D/E Resin (Bisco), Optibond All-in-one and NX3 DC (Kerr), Scotchbond Multi-Purpose Plus (3M ESPE). The Amalgam material used was Valiant PhD-XT (Ivoclar).

Eighty extracted third molars were used. The teeth were sectioned mesial to distal and one half of each tooth was embedded in acrylic. Dentin was exposed, polished with 320-grit SiC sandpaper. All bonding systems were used following manufacturers' directions. Size #1 copper band was used in an Ultradent jig to allow the amalgam condensation on the prepared dentin surface (n=20). Half of the specimens in each group were kept in water at 37⁰C for 24-hour and another half were stored for 24-hour water and 500 thermal cycles between 5°C and 55°C. The shear bond strength was determined using an MTS mechanical tester at a crosshead speed of 1.0 mm/min.

Results:

The test results (in MPa) are listed.

Conclusion:

Thermal cycling for 500 cycles significantly increased the bonding strength between amalgam and dentin.