Detecting demineralisation adjacent to veneer restorations using QLF

Method: Thirteen bovine teeth devoid of stains and cracks were selected, the roots removed and enamel gently pumiced. Porcelain veneers measuring approximately 3 x 3 mm were made in the laboratory. These were treated with silane primer (Kerr corporation, U.S.A) and bonded to etched teeth surfaces according to the manufacturer instructions using the Optibond and Nexus 2 universal luting systems (Kerr corporation, U.S.A).The margins were examined for excess bonding material and cleaned using soflex discs. The teeth were rinsed in deionised water, air-dried and examined under QLF for stains.Windows were created superior and inferior to the veneer margins using acid resistant varnish. After leaving to dry for 24 hours, the teeth were mounted on glass rods attached to pot lids using green stick. Baseline QLF images were taken and the teeth were immersed into universal pots containing demineralising solution. QLF images were captured at 3, 6, 9, 12, 24, 36, 48 and 60 hours.

Results: A total of 117 images were analysed and the degree of mineral loss (Delta F values at 5% threshold) obtained. Demineralisation adjacent to the restorations was detected in all the teeth by QLF. Using paired t-tests there was a significant treatment effect between the baseline images and the 60-hour demineralised images (p<0.05). There was a significant correlation between the time of exposure and the degree of demineralisation as measured by Delta F (Pearson coefficient =0.89, r2 =0.79)

Conclusion: QLF was able to detect longitudinally demineralisation around porcelain veneer restorations in vitro.