Introduction: “In-office” bleaching techniques are popular methods of tooth whitening. The purpose of this study was to compare the alteration of tooth color after Plasma arc and Laser bleaching.Materials and Methods: Thirthy freshly extracted human mandibular central incisors were selected, embedded in Rose wax and polished with pamis powder; samples were then randomly divided into 2 groups of 15 each including Plasma arc bleaching group and Laser bleaching group. Color of all specimens was evaluated by Spectrophotometer 7000A. The specimens were evaluated for color before treatment as a control group.The Plasma arc bleaching group was bleached with Ever Brite gel which was activated by Plasma arc machine according to the company introduction, then stored in normal saline. The Laser bleaching group were bleached with Laser smile (35% H2O2), which was twice activated by 810nm Diode Laser in one visit for 7 and 4 minutes. Samples were then stored in normal saline. All of the specimens reevaluated for color alteration after treatment.Results: Both techniques can change and vary tooth color into white and reduced yellowness ratio; i.e. Delta E decreased 1.73 in Laser bleaching and 2.86 in Plasma arc, so Plasma arc bleaching change tooth color 1.65 times more than Laser Bleaching.Conclusion: Although both Laser and Plasma arc bleaching can vary tooth colors, after Plasma arc bleaching the alteration of tooth color is more than Laser bleaching. According to this study, the Plasma arc bleaching is more effective than Laser bleaching with Diode laser for in-office bleaching.
