Dental Bleaching with Phthalocyanine Photosensitizers: Effects on Dentin Color and Collagen Content

Abstract

With the increasing demand for tooth bleaching in esthetic dentistry, its safety has been the focus of a comprehensive body of literature. In this context, the aim of the present study was to evaluate the application effects of pentalysine β-carbonylphthalocyanine zinc (ZnPc(Lys)5)-mediated photodynamic therapy in dentin bleaching and its effects on dentin collagen. We first established a new and reproducible tooth staining model using dentin blocks stained by Orange II and then bleached with ZnPc(Lys)5 (25 μM) and hydrogen peroxide (10% or 30%). Data were analyzed with one- and two-way ANOVA and a significance level of p < 0.05. ZnPc(Lys)5 effectively bleached the dentin samples to an extent comparable to hydrogen peroxide at either 10% or 30% concentrations. Further studies on the dentin morphology, chemical element distribution, and protein constituents, using an electron microscope, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and SDS-PAGE, demonstrated that treatment with the photosensitizer preserved the dentin structure and, at the same time, the major organic component, collagen type I. For comparison, hydrogen peroxide (10% or 30%) treatment significantly degraded the collagen protein. This work indicated that the photosensitizer exerts potent bleaching effects on dentin staining; importantly, does not damage dentin and its collagen content; and opens up a new strategy to further explore various photosensitizers for the bleaching of both tooth enamel and dentin.

Evaluation of the effects of different photosensitizers used in antimicrobial photodynamic therapy on tooth discoloration: spectrophotometric analysis

“…The fact that there was more tooth discoloration in the TM-ZnPc group than in the Pc group compared to the baseline may be due to the greater binding of the substituted Zn to collagen [ 54 ]. In the present study, the increased tooth discoloration in TB MB and TM-ZnPc compared to baseline may be due to their higher binding to organic tissues [ 55 – 57 ].…”