An in vitro and in vivo study of plasma treatment effects on oral biofilms

Qing Hong,Xiaoqing Dong,Meng Chen,Hongmin Sun,Liang Hong,Yong Wang,Hao Li,Qingsong Yu

doi:10.1080/20002297.2019.1603524

Abstract

ABSTRACTManagement of dental plaque/biofilms is critical to maintain oral health. The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on oral biofilm formation and recovery under in vitro and in vivo conditions. Streptococcus mutans biofilms, a significant contributor to tooth decay, were cultured and treated by plasma. It was found that plasma treatment not only significantly reduced the in vitro biofilms, but also increased the metabolic activity of the bacteria in the biofilms. As compared with untreated control group, the cell metabolic activity, as measured by MTT assay, increased by 273%, and the aconitase activity increased by 446% for the plasma-treated group. The increased metabolic activity of the plasma-treated biofilm bacteria enhanced their susceptibility to antibiotic and host defense. An in vivo animal model using a total of 60 female rats (19 days old) were used to evaluate the anti-caries effects on the molars by 2 min of plasma treatment. It was found that, 6 months after the plasma treatment, the decayed surfaces were reduced by 62.5% on the upper molars and by 31.6% on the lower molars as compared with the untreated upper and lower molars, respectively. These in vitro and in vivo data demonstrate that the physiological state change of the biofilm due to plasma treatment provided benefit to caries control and prevention.

Highlights

Dental plaque is the collection of microorganisms adhering to a tooth surface as a biofilm
Biofilm was reduced by 70% on stainless steel wafers after 2 min of plasma treatment characterized by crystal violet (CV) staining measurement (Figure 1(a))
The slime production of biofilm decreased from OD = 1.32 to OD = 0.12 as the plasma treatment time increased from 0 min to 2 min (Figure 1(b))

Summary

Introduction

Dental plaque is the collection of microorganisms adhering to a tooth surface as a biofilm. EPS allow biofilms to develop complex threedimensional, resilient, and attached communities. Numerous studies have shown that dental plaque is one of the significant factors causing dental caries, periodontitis, and other oral infections [4]. Management of dental plaque is critical to maintain oral health. The current therapeutic strategy to control dental plaque usually involves mechanical removal and the use of chemical agents. Scaling (removal of calculus and plaque), root planning (removal of necrotic tooth tissue on the root surface), and surgery (to remove tissue and reduce pocket depth) are the most common removal methods of supra and subgingival plaque in periodontal therapies [5]. The mechanical procedures undoubtedly remove most organisms colonizing the tooth surface

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Discussion

Conclusion