Methods: Eighty cylinders of Ni-Cr were randomly allocated into the following groups: Group I – sandblasting only; Group II – low laser fluence (3.0 J/cm2); Group III – medium laser fluence (4.0 J/cm2); Group IV – high laser fluence (4.9 J/cm2); Group V –sandblasting in combination with medium laser fluence (4.0 J/cm2). Specimens within groups were bonded into pairs with resin cement as per manufacturer’s instructions. They were then de-bonded using a tensile test.
Results: The mean de-bond strengths (s.d.) were: Group I – 13.1 (4.2)MPa; Group II – 17.6 (5.8)MPa; Group III – 25.7 (11.8)MPa; Group IV – 22.6 (6.6)MPa; Group V – 41.8 (13.2)MPa. A statistically significant improvement (Bonferroni, p<0.05) in bond strength was found for the specimens which had been both lased and sandblasted (Group V) compared to all other groups, including those which were only sandblasted.
Conclusions: Laser pre-treatment of Ni-Cr alloy increases bond strength to composite resin compared with sandblasting; laser pre-treatment in combination with sandblasting further increases the de-bond strengths.