Intrinsic Staining and Whitening Assessment using QLF

Objectives: The aim of this study was to detect and quantify intrinsic stain uptake and its removal on the labial surfaces of teeth using Quantitative Light induced Fluorescence (QLF). Methods: Fourteen bovine teeth devoid of stains were selected, the roots removed and enamel gently pumiced. Access cavities were created via the lingual surface and root canals of these teeth. The labial surfaces of the teeth were coated with acid resistant clear nail varnish and left to air dry for 24 hours. The teeth were attached to lengths of cotton and suspended in pots containing 30 ml of tea solution. The teeth were left in the tea solution and gently stirred for six days with the solution changed daily. Stain uptake was recorded with QLF™ (Inspektor Research systems BV, NL) on the sixth day. The stain values (delta F) from QLF were obtained using the inner patch technique. Prior to taking the readings, the varnished surfaces of the teeth were wiped clean of any extrinsic stains using a wet cotton swab stick and left to bench dry for ten minutes. After the sixth day, the teeth were removed from the tea solution and immersed in pots containing 30ml solutions of 33% hydrogen peroxide. QLF readings were taken after 150 minutes post-immersion. Results: The uptake of stain was detected in all the teeth by QLF. Using paired t- tests, there was a significant difference in stain uptake between the baseline and final stain cycle (p<0.01). Removal of the intrinsic stain was also detected by QLF. There was a significant difference between the beginning of bleaching and the final bleaching cycle (p<0.01) Conclusion: QLF was able to detect and quantify the uptake and removal of intrinsic stains on teeth surfaces