High Resolution TEM Characterisation of Hydrogen Peroxide Treated Tooth Structures

Abstract

Objective: Previous studies reported that bleaching agents are capable of altering the outer enamel or exposed dentine surfaces. In this study, transmission electron microscopy (TEM) characterisation in combination with energy dispersive x-ray spectroscopy (EDS) elemental mapping was performed to investigate the effect of hydrogen peroxide (HP) on the sub-surface of tooth structures. Materials and Methods: Bovine incisors (n=6) were assigned to three groups for treatments: 30% H2O2 pH 3, 30% H2O2 pH 7 and 1M sodium hydroxide (NaOH) for 16 hours. Samples were exposed to direct treatment with agents to allow easy access of the agents and uniform treatment across the entire sample sub-surfaces. Specimens were immersed in Karnovsky’s fixative for three days, embedded in epoxy and polished. Using focussed ion beam (FIB), samples were milled ~50-100 μm below the treated polished surface to feature the ultra-fine structures for TEM analysis.