口腔内細菌種に対する歯磨剤の有効性評価のための微生物学的アプローチ。方法の比較

Microbial approaches for the assessment of toothpaste efficacy against oral species: A method comparison.

抄録

歯磨剤の抗菌性により，歯ブラシでは十分に行き届かない歯の限られた部位における化学的プラークコントロールが可能となる．そこで本研究では，歯磨剤の抗菌性を評価するための異なる微生物学的手法を比較し，in vitro環境において，異なる口腔内細菌に対する抗菌効果の観点から異なる歯磨剤の評価を行うことを目的とした．抗菌成分の異なる6種類の歯磨剤懸濁液を，多種のバイオフィルムモデル（Actinomyces oris，Candida albicans，Fusobacterium nucleatum，Streptococcus oralis，Streptococcus mutans）および各微生物に適用し，抗菌効果を評価した．抗バイオフィルム効果の評価には培養法を用い、各微生物に対する抗菌効果の試験には2種類の寒天拡散アッセイを実施した。培養法と拡散法の測定値を統計的に正規化して比較し，歯磨き粉を抗菌効果に応じてランク付けした．両寒天拡散試験の結果は，試験したすべての菌種で高い相関を示した（Spearman相関係数ρ >0.95）．しかし，多菌種バイオフィルムモデルの結果は，両拡散アッセイの結果と比較して，抗菌性の評価に大きな差が認められた（ρは0.22～0.87の範囲）．フッ化アミン（フッ化スタンナスを含む）およびトリクロサンを配合した歯磨剤で最も高い抗菌効果が得られた．歯磨剤に配合した活性炭は，陰性コントロールであるNaClと同等の抗菌作用を示した．歯磨剤および歯磨剤添加物の化学的影響を試験する際には，広範囲の口腔内微生物を適切に選択することが重要であると思われる．

Antibacterial properties of toothpastes enable chemical plaque control in limited-access tooth regions that are mechanically not sufficiently reached by toothbrushes. Therefore, this study aimed to compare different microbial methods to assess antimicrobial toothpaste properties and evaluate different toothpastes in terms of their antibacterial efficacy against different oral microorganisms in an in vitro setting. Six toothpaste suspensions with varying antibacterial supplements were applied to a multispecies biofilm model (Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, and Streptococcus mutans) as well as to each microorganism. A culture method was used to assess the anti-biofilm effects and two different agar diffusion assays were performed for testing the antimicrobial effect on each microorganism. The measurements of the culture and diffusion analyses were statistically normalized and compared and toothpastes were ranked according to their antimicrobial efficacy. The results of both agar diffusion assays showed a high correlation across all tested species (Spearman correlation coefficients ρ  > 0.95). The results of the multispecies biofilm model, however, substantially differed in its assessment of antibacterial properties (ρ ranging from 0.22 to 0.87) compared to the results of both diffusion assays. Toothpastes with amine fluoride (with and without stannous fluoride), and toothpastes with triclosan resulted in the highest antimicrobial efficacy. Activated carbon supplements in toothpastes were comparable in their antimicrobial action to the negative control NaCl. The appropriate selection of a broad range of oral microorganisms seems crucial when testing the chemical impact of toothpaste and toothpaste supplements.