Development of a graphene oxide/hydroxyapatite-containing orthodontic primer: An in-vitro study

Abstract

Fixed orthodontic appliances increase the risk of enamel demineralization and the development of white spot lesions (WSLs). This study aimed to develop a novel orthodontic primer that incorporates graphene oxide (GO) and hydroxyapatite (HA), investigate their cell viability, bonding strength, and enamel damage, and evaluate their antibacterial and remineralization properties. Nine groups were prepared by adding different concentrations of GO (0.1, 0.25, and 0.5 wt%) and HA (2, 5, and 7 wt%) to Transbond™ XT orthodontic primer. After observing the surface morphology of the material by a Field Emission Scanning Electron Microscope (FESEM), the phase of the materials by X-ray diffraction (XRD), and their chemical compositions by Energy Dispersive X-ray spectroscopy (EDX). The prepared primers were compared to the control primer group in terms of cell viability, shear bond strength (SBS), adhesive remnant index (ARI), enamel damage index (EDI), and antibacterial test. Then the groups with higher antibacterial properties (GOHA 0.1–2, GOHA 0.1–5, GOHA 0.25–2) were selected to evaluate their remineralization properties. Primers with all the prepared concentrations of GO/HA revealed acceptable cell viability levels within the limit of the ISO standards with comparable SBS and ARI values with the control primer (p > 0.05). Simultaneously, the EDI significantly reduced, and the antibacterial properties enhanced when compared to the control group (p < 0.05). The result of remineralization properties revealed that the selected groups had significantly higher remineralization ability than the control group which was more pronounced in GOHA 0.25–2 group. All the prepared orthodontic primers with different concentrations of GO/HA are safe biologically with adequate SBS, ARI, and EDI values for clinical application with enhanced antibacterial properties. The GOHA 0.25–2 experimental primer reveals the best antibacterial and remineralization properties which require further in-vitro and in-vivo investigation as a preventive measure of WSL.