Novel Orthodontic Cements for Prevention of Enamel Demineralization Around Brackets

Objectives: White spot lesions due to biofilm acid-induced enamel demineralization are prevalent in orthodontic treatments. The aim of this study was to develop a novel bioactive multifunctional cement with protein-repellent, antibacterial and remineralizing capabilities, and investigate the effects on preventing enamel demineralization in vitro for the first time.

Methods: Protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC), antibacterial dimethylaminohexadecyl methacrylate (DMAHDM), and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into a resin-modified glass ionomer (RMGI). Extracted human premolars had brackets bonded via four groups: (1) Transbond XT (TB), (2) GC Fuji Ortho (GC), (3) GC+MPC+DMAHDM, (4) GC+MPC+DMAHDM+NACP. Demineralization was induced via a dental plaque microcosm biofilm model for two weeks. Samples were subsequently evaluated using polarized light microscopy (PLM), cross-sectional hardness and scanning electron microscopy (SEM).

Results: Incorporation of MPC, DMAHDM and NACP did not affect shear bond strength. PLM analysis showed that “GC+MPC+DMAHDM+NACP” had the least lesion depth at all measuring ranges (p < 0.05). Groups with NACP had the highest enamel hardness (p < 0.05). Mineral loss (ΔS) of cement containing NACP was about one third that of GC control. “GC+MPC+DMAHDM” had moderate effect on demineralization-inhibition, compared to GC control. “GC+MPC+DMAHDM+NACP” and “GC+MPC+DMAHDM” were more effective in protecting enamel prisms from dissolving, than commercial controls.
Conclusions: There was a significant preventive effect of “GC+MPC+DMAHDM+NACP” cement in reducing enamel demineralization adjacent to orthodontic brackets from biofilm acids. This novel triple-agent bioactive cement is promising to prevent enamel white spot lesions in orthodontic treatments.