A novel tooth bleaching gel based on peroxymonosulfate/polyphosphates advanced oxidation process: Effective whitening avoiding pulp damage and sensitivity

Pulp damage and bleaching sensitivity caused by existing hydrogen peroxide (HP) bleaching gel is a major challenge that needs to be solved urgently in the field of vital bleaching, mainly due to HP’s intrinsic high penetrability and strong oxidative property. The present study has successfully developed a novel non-hydrogen peroxide bleaching system based on peroxymonosulfate (PMS)/polyphosphates advanced oxidation process, with suitable penetration depth in dental structure. In addition to oxidizing active ingredients similar to HP gel, the new PMS gel also contains its characteristic free radical---•SO4−. Benefitting from excellent oxidative performance, novel bleaching gel exhibits a favorable tooth whitening effect. And tooth color stability after bleaching is better because it only induces a minor change on the enamel surface. Furthermore, cytological studies demonstrate that the new gel has less damage to human dental pulp fibroblasts (cell viability reaches 87.5% after 2 h’ exposure), which is mainly due to the relatively low content of oxidant (15.4%) and limited penetration depth (middle dentin). More excitingly, histological results show PMS gel applied on the molars of rats induce no inflammation of pulp tissues and no activation of pain-related receptors or peptides, consistent with the performance of blank control. These findings suggest that the new PMS/polyphosphates bleaching system has the advantages of good bleaching effectiveness, minor enamel alterations and non-damaged pulp tissue. It is expected to provide a new strategy for clinical vital bleaching treatment.