Expanding the applications of photodynamic therapy-tooth bleaching

Abstract

Objectives: The current tooth bleaching materials are associated with adverse effect. Photodynamic method based on a novel photosensitizer alone, without combining with peroxides, is evaluated for tooth bleaching application.

Materials and methods: Teeth samples were randomly divided into 3 groups with different treatment schemes, including negative control group (group A, physiological saline), experimental group (group B, ZnPc(Lys)₅), and the positive control group (group C, hydrogen peroxide). Tooth color, surface microhardness, and roughness were determined at baseline, right after the first and second phase of bleaching, as well as 1 week and 1 month post-bleaching. Four samples in each group was randomly selected to evaluate the changes in surface morphology using the scanning electron microscope.

Results: The color change values (ΔE) in group B (7.10 ± 1.03) and C (12.22 ± 2.35) were significantly higher than that in group A (0.93 ± 0.30, P < 0.05). Additionally, surface microhardness and roughness were significantly affected in group C, but not in the group A and B. Furthermore, the scanning electron microscope images showed no adverse effect of enamel in the group A and B while the group C demonstrated corrosive changes.

Conclusions: ZnPc(Lys)₅ had a satisfactory bleaching effect and is promising to be a new type of tooth bleaching agent.

Clinical relevance: The current tooth bleaching materials give a satisfactory clinical outcome and long-term stability, but associated with some adverse reactions. Photosenstizer ZnPc(Lys)₅ eliminated the main side effects observed in hydrogen peroxide-based agents on the enamel, and also had a satisfactory bleaching effect and provide a novel selective bleaching scheme for clinical use.

Keywords: Photosensitizer; Scanning electron microscope; Surface microhardness; Surface roughness; Tooth bleaching.