Influence of Light and Laser Activated Tooth Bleaching on Enamel Microhardness and Surface Roughness
Mohd Yusof E1, Abdullah SA1, Mohamed NH2
1. Faculty of Dentistry, University of Malaya, Kuala Lumpur
2. Department of General Dental Practice, Faculty of Dentistry, University of Malaya, Kuala Lumpur
Objectives : To evaluate the effects of tooth bleaching on enamel microhardness and surface roughness upon application of hydrogen peroxide activated by light (BeyondTM) and (LaserSmileTM) at day 2, day 7 and day 28.
Methods : 25 enamel slabs embedded in epoxy resin was prepared. The enamel surface was polished using 1200-grit silicon carbide paper. The specimens were the dividedinto three treatment groups; control (5 slabs), light-activated (10 slabs) and laser –activated (10 slabs) and store in distilled water at 370C. Baseline data was collected for microhardness and surface roughness. For Light-activated bleaching, after application of 25% hydrogen peroxide gel, the specimen surface was activated with light (BeyondTM) for 10 minutes. Reapplication of gel is repeated for another cycle. For laser-activated (LaserSmileTM) bleaching, the hydrogen peroxide was activated with laser; 8 cycle for 10 seconds each cycle. Vickers microhardness testing machine was used to determine changes in enamel microhardness after tooth bleaching. Surface roughness was evaluated using surface texture analyzer. Changes in enamel microhardness and surface roughness were evaluated on day 7 and 28 after the bleaching treatment for both intervals.
Results : The effects of hydrogen peroxide bleaching on enamel surface microhardness were not statistically significant between the specimens groups of different time intervals except for light. Light activated bleaching does cause microhardness reduction.
Conclusion : There were statistically significant differences in surface roughness in laser and light groups. The readings show that bleaching does cause surface roughness alterations of different time intervals.
Keywords: tooth bleaching, enamel hardness, enamel roughness, laser-activated
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