OBJECTIVES: The bond strengths of new composite to composite aged in water for 0,1,4 and 12 weeks was investigated (Dent Mater. 2007, 23: 519-25). The present study compared the value for the same materials after aging for 3 years. METHODS: Forty cylinders (dia 5mm x 4mm) of each of the three composites 1-3 were fabricated and stored in water for 3 years. The samples surfaces were treated prior to bonding a second increment. The treatments were: (1) a layer of Prime and Bond4, (2) abrasion on 600 grit SiC paper +Prime & Bond, (3) a layer of Optibond Solo Plus5, (4) abrasion+Optibond SP. One end of the specimen was embedded in PMMA for fixing in the testing machine. The protruding end was loaded to failure with a crosshead speed of 25 mm/min. Ten specimens per treatment were tested. The fracture surface of a number of specimens were sputter coated and examined by high power stereo microscopy. The results at 3 years were included in a MANOVA analysis with the data from 0,1,4 and 12 weeks.
RESULTS:
Prime & Bond | Abrade+P&B | Optibond Solo | Abrade+Optibond | |||||
12W | 3Y | 12W | 3Y | 12W | 3Y | 12W | 3Y | |
Spectrum | 40.4 | 33.1 | 41.2 | 36.5 | 41.3 | 37.7 | 45.3 | 36.4 |
Durafil | 27.6 | 21.9 | 27.3 | 25.6 | 29.1 | 24.6 | 27.4 | 25.1 |
Herculite | 32.3 | 26.3 | 38.06 | 31.8 | 33.5 | 28.3 | 33.6 | 29.7 |
Value = Mean shear stress at failure (MPa). P&B = Prime & Bond. 12W =12 Weeks. 3Y = 3 Years
The values at 3 Years were less than at 12 weeks. The MANOVA test confirmed that the material and treatments were also significant variables. Microscopy indicated that the fracture line deviated back into the aged composite. CONCLUSION: In this study two dentine bonding agents enabled relatively high bond strengths to be achieved to composite that had been aged in water for 3 years. The additional use of abrasion did not improve the bond strengths.
1Spectrum, Dentsply, UK., 2 Durafill, Heraeus Kulzer, 3 Herculite, Kerr Dental 4Prime and Bond, Dentsply, 5 Optibond Solo Plus, Kerr Dental