Novel Dental Cement to Combat Biofilms and Reduce Acids for Orthodontic Applications to Avoid Enamel Demineralization.

Ning Zhang,Nancy Lin,Mary Melo,Joseph Antonucci,Yuxing Bai,Hockin Xu,Sheng Lin-Gibson

doi:10.3390/ma9060413

Abstract

Orthodontic treatments often lead to biofilm buildup and white spot lesions due to enamel demineralization. The objectives of this study were to develop a novel bioactive orthodontic cement to prevent white spot lesions, and to determine the effects of cement compositions on biofilm growth and acid production. 2-methacryloyloxyethyl phosphorylcholine (MPC), nanoparticles of silver (NAg), and dimethylaminohexadecyl methacrylate (DMAHDM) were incorporated into a resin-modified glass ionomer cement (RMGI). Enamel shear bond strength (SBS) was determined. Protein adsorption was determined using a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU) and lactic acid production. Incorporating 3% of MPC, 1.5% of DMAHDM, and 0.1% of NAg into RMGI, and immersing in distilled water at 37 °C for 30 days, did not decrease the SBS, compared to control (p > 0.1). RMGI with 3% MPC + 1.5% DMAHDM + 0.1% NAg had protein amount that was 1/10 that of control. RMGI with triple agents (MPC + DMAHDM + NAg) had much stronger antibacterial property than using a single agent or double agents (p < 0.05). Biofilm CFU on RMGI with triple agents was reduced by more than 3 orders of magnitude, compared to commercial control. Biofilm metabolic activity and acid production were also greatly reduced. In conclusion, adding MPC + DMAHDM + NAg in RMGI substantially inhibited biofilm viability and acid production, without compromising the orthodontic bracket bond strength to enamel. The novel bioactive cement is promising for orthodontic applications to hinder biofilms and plaque buildup and enamel demineralization.

Highlights

Orthodontic therapies with fixed appliances often lead to biofilm buildup with increased cariogenic bacteria which are difficult to clean around the brackets [1,2]
The The enamel shear bond (SBS)ofoforthodontic orthodontic cements are plotted in Figure enamel shear bondstrengths strengths (SBS)
Testing the various compositions of cements showed that methacryloyloxyethyl phosphorylcholine (MPC) could repel proteins but had no antibacterial effect; dimethylaminohexadecyl methacrylate (DMAHDM) and NAg could kill bacteria but could not repel proteins; and the application of triple agents MPC + DMAHDM + NAg inhibited biofilm viability to a much greater extent than using a single agent or double agents

Summary

Introduction

Orthodontic therapies with fixed appliances often lead to biofilm buildup with increased cariogenic bacteria which are difficult to clean around the brackets [1,2]. The incidence of enamel white spot lesions in orthodontic patients was reported to be as high as 50% [4]. Clinical observations showed that the most common sites for white spot lesions are at the junctions of the orthodontic cement and tooth enamel [3]. Orthodontic cements around the brackets tend to accumulate biofilms due to their relatively rough surfaces [2,5]. With increasing demand for esthetics around the world and growing popularity of orthodontic treatments, it would be meritorious to fabricate a new orthodontic cement with bioactive capability to inhibit biofilm buildup and acid production around orthodontic brackets

Objectives

Methods

Discussion

Conclusion