## 4 Discussion  
In this study, we analyzed the qualitative and quantitative changes in oral bacteria of OLP patients. After 4 weeks of corticosteroid gargle use, 75% of the OLP patients had a changed microbial community composition. The amount of change was significant except for _Treponema danticola_ and _Streptococcus sobrinus_. Overall, the total number of microbes appeared to decrease, but there was no consistent result for all patients or bacterial species. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{8}{c}{**Relative Fluorescence Unit (RFU)**} \\ \cline{2-10}
**Patient Number** & \(Pg\)** & \(Tf\)** & \(Td\)** & \(Fn\)** & \(Pi\)** & \(Pnt\)** & \(Sm\)** & \(Smu\)** & \(Ss\) \\  & **(10\({}^{5}\))** & **(10\({}^{5}\))** & **(10\({}^{4}\))** & **(10\({}^{6}\))** & **(10\({}^{6}\))** & **(10\({}^{4}\))** & **(10\({}^{6}\))** & **(10\({}^{5}\))** & **(10\({}^{5}\))** \\ \hline Total & 1.5 (2.1) & 1.5 (1.8) & 0.7 (1.5) & 1.2 (1.7) & 1.1 (2.2) & 1.1 (1.2) & 2.5 (2.8) & 1.2 (1.5) & 0.5 (1.9) \\ \(p\)-value \({}^{\star}\) & 0.001 & 0.002 & 0.068 & 0.000 & 0.018 & 0.001 & 0.000 & 0.008 & 0.180 \\ \hline \hline \end{tabular}  
* Pg, Porphyromonas gingivalis; Tf, Tannerella forysthia; Td, Treponema danticola; Fn, Fusobacterium nucleatum; Pi, Prevotella intermediia; Pn, Prevotella nigrescens; Sm, Streptococcus mitris; Smu, Streptococcus mutans; Ss, Streptococcus sobrinus. *: Wilcoxon signed-rank test.  
\end{table} 
Table 2: Absolute quantitative changes in the oral microbial species of oral lichen plants patients before and after treatment with dexamethasone gargle. Figure 3: Quantitative changes in oral microbial species in OLP patients after 4 weeks of dexamethasone gargle. (Pg: _Porphyromonas gingivalis_, 10\({}^{5}\) RFU; Tf: _Tannerella forysthia_, 10\({}^{5}\) RFU; Td: _Treponema danticola_, 10\({}^{4}\) RFU; Fn: _Fusobacterium nucleatum_, 10\({}^{6}\) RFU; Pi: _Proctella intermedia_, 10\({}^{6}\) RFU; Pn: _Prevotella nigrescens_, 10\({}^{4}\) RFU; Sm: _Streptococcus mutans_, 10\({}^{6}\) RFU; Ss: _Streptococcus subrinus_, 10\({}^{5}\) RFU). In the human oral cavity, about 700 bacterial species of phylogenies are identified as essential for maintaining a healthy condition, but some oral pathogens may exert the ability to differently trigger the activation of local immune responses with an imbalance of pro-inflammatory and anti-inflammatory gene responses [13; 14; 15]. The effect of the oral microbial population has not yet been clarified in the development of OLP, which is considered an oral immune disease. [PERSON] et al. first reported in 1984 that 37-50% of OLP patients had candidiasis [16]. Until 2000, _Helicobacter pylori_ was the only bacterium believed to be attributed to OLP [17; 18]. In 2008, [PERSON] et al. showed high bacterial counts of _Bacteroides ureolyticus_, _Dialister_ species, _Staphylococcus haemolyticus_, _and Streptococcus agalactiae_ in OLP lesions by using a closed-format checkerboard DNA-DNA hybridization method [19]. In this present study, _Fn_ and _Sm_ were detected in all OLP patients, and the other species were observed in the following order: _Pt (75%)_, _Tf (65%)_, _Pg (55%)_, _Smu (40%)_, _Pi (30%)_, _Td (15%)_, and _Ss (10%)_. However, the relationship could not be elucidated between OLP development and microbial species because no comparison was made with healthy patients without OLP. Although OLP is associated with T-lymphocytes without bacterial infection, it can be affected by oral pathogens that secrete endotoxins and stimulate the immune system [2]. In 1990, [PERSON] et al. found that intensive oral hygiene management improved symptoms in patients with atrophic and ulcerative OLP [20]. In 2007, chlorhexidine treatment was shown to significantly relieve the symptoms of OLP [21]. These reports suggested that the oral microbial community may interact with the symptoms or development of OLP. On the other hand, immunomodulatory activity can affect the oral microbial community while suppressing the immunologic system during OLP treatment.