Effect of hydrogen peroxide concentration on plasma arc-activated tooth bleaching: An in vitro study.

Background/purpose: Tooth bleaching was a conservative treatment compared with veneer and crown restorations that causes damage of teeth structure. This study evaluated the effectiveness of different concentrations of hydrogen peroxide combined with plasma arc activation for tooth whitening, focusing on tooth shade, microhardness, and surface roughness. Materials and methods: The extracted teeth were standardized to ensure consistent surface conditions. They were bleached using various concentrations of 20 %-35 % hydrogen peroxide, with or without plasma arc activation. After the bleaching process, the shade, microhardness, and surface roughness of the teeth were measured before, during, and after the first and fourth bleaching cycles. Results: The concentration of hydrogen peroxide significantly affected tooth color changes following a single plasma arc bleaching cycle. After the fourth cycle, all concentrations except for the 23 % hydrogen peroxide showed effects on tooth color and microhardness due to plasma arc activation, with roughness being the most notably impacted indicator. Therefore, while plasma arc treatment enhanced the efficacy of tooth whitening, it also significantly reduced microhardness, especially within the hydrogen peroxide concentration range of 26 %-35 %. Conclusion: We suggest using a 26 % peroxide solution instead of high-concentration hydrogen peroxide, activated by a plasma arc, to achieve the same teeth whitening results while minimizing damage to the tooth surface.