舌の清掃が舌苔および歯垢中の細菌叢に及ぼす影響：クロスオーバー試験

Effects of tongue cleaning on bacterial flora in tongue coating and dental plaque: a crossover study.

抄録

背景:

舌の清掃が歯垢や舌苔の細菌叢の再構築に及ぼす影響は不明である。我々は、舌清掃の有無による舌苔と歯垢の総菌量およびFusobacterium nucleatumの量の変化を評価した。

BACKGROUND: The effects of tongue cleaning on reconstruction of bacterial flora in dental plaque and tongue coating itself are obscure. We assessed changes in the amounts of total bacteria as well as Fusobacterium nucleatum in tongue coating and dental plaque specimens obtained with and without tongue cleaning.

方法:

歯周炎を持たないボランティア 30 名（平均 23.7 ± 3.2 歳）を対象に、無作為化試験官盲検クロスオーバー試験を実施した。無作為に2群に分け、1群には舌の洗浄を指示し、もう1群には舌の洗浄を指示しなかった。1日目（ベースライン），3日目，10日目に，舌苔と歯垢を採取し，舌苔スコア（Winkel tongue coating index：WTCI）を記録した．3週間のウォッシュアウト期間の後，代替群に割り当てられた被験者で同様の検査を行った．検体からゲノムDNAを精製し、SYBR® Green-based real-time PCRを用いて、総菌量およびF. nucleatumの量を定量した。

METHODS: We conducted a randomized examiner-blind crossover study using 30 volunteers (average 23.7 ± 3.2 years old) without periodontitis. After dividing randomly into 2 groups, 1 group was instructed to clean the tongue, while the other did not. On days 1 (baseline), 3, and 10, tongue coating and dental plaque samples were collected after recording tongue coating score (Winkel tongue coating index: WTCI). After a washout period of 3 weeks, the same examinations were performed with the subjects allocated to the alternate group. Genomic DNA was purified from the samples and applied to SYBR® Green-based real-time PCR to quantify the amounts of total bacteria and F. nucleatum.

結果:

3日後、WTCIスコアはベースラインまで回復したが、舌苔の総菌量はベースラインと比較して有意に少なかった。歯垢では、3日目および10日目の菌量は、舌の清掃の有無にかかわらず、ベースラインより有意に少なかった。主成分分析の結果、舌苔と歯垢の菌量の変動は互いに独立したものであった。さらに、総菌量とF. nucleatumの菌量には強い相関が見られた。

RESULTS: After 3 days, the WTCI score recovered to baseline, though the amount of total bacteria in tongue coating was significantly lower as compared to the baseline. In plaque samples, the bacterial amounts on day 3 and 10 were significantly lower than the baseline with and without tongue cleaning. Principal component analysis showed that variations of bacterial amounts in the tongue coating and dental plaque samples were independent from each other. Furthermore, we found a strong association between amounts of total bacteria and F. nucleatum in specimens both.

結論:

舌の清掃は舌苔の細菌量を減少させた。しかし，舌清掃は歯垢形成の抑制には寄与していなかった．また，総菌量の回復により，舌苔と歯垢の両方でF. nucleatumの増加が認められた．したがって，口腔内の健康増進のためには，舌の清掃と歯磨きの両方を行うことが推奨される．

CONCLUSIONS: Tongue cleaning reduced the amount of bacteria in tongue coating. However, the cleaning had no obvious contribution to inhibit dental plaque formation. Furthermore, recovery of the total bacterial amount induced an increase in F. nucleatum in both tongue coating and dental plaque. Thus, it is recommended that tongue cleaning and tooth brushing should both be performed for promoting oral health.