ホワイトニング歯磨き粉の象牙質表面に対する長期的な研磨・侵食効果

Longterm abrasive and erosive effect of whitening toothpaste on dentin surface.

抄録

目的:

過酸化水素(HP)とクエン酸(CA)を含むホワイトニング歯磨き粉(WT)に浸漬した後、または歯磨きした後の象牙質の損失量を評価すること。さらに、WT単独または従来の歯磨剤との併用によるブラッシング後の象牙質喪失量を評価し、HPおよびCA溶液の象牙質表面への影響を調べた。

PURPOSE: To evaluate the amount of dentin loss following immersion in or toothbrushing with whitening toothpaste (WT) containing hydrogen peroxide (HP) and citric acid (CA). Additionally, the amount of dentin loss after brushing with a WT alone or in combination with a conventional toothpaste was assessed, and the effects of HP and CA solutions on the dentin surface were investigated.

方法:

牛歯象牙質標本（n= 350）を歯磨剤として様々な組成の7種類の溶液に無作為に割り付けた：各溶液に割り当てられた標本は、さらに5つの処理群（n=10ずつ）に分けられた：グループA＝各溶液に1時間浸漬（ES）；グループB＝ESで10,000回ブラッシング；グループC＝ESに1時間浸漬＋ESで10,000回ブラッシング；グループD＝ESに1時間浸漬＋参照用スラリーで10,000回ブラッシング（RS）；グループE＝ESで10,000回ブラッシング＋RSで10,000回ブラッシング。象牙質喪失の量とパターンを決定し、非接触式プロフィロメトリーで表面を観察した。

METHODS: Bovine dentin specimens (n= 350) were randomly assigned to seven solutions of various compositions as toothpaste: The specimens assigned to each solution were then further divided into five treatment groups (n=10 each) : Group A = 1-hour immersion in each solution (ES); Group B = 10,000 brushing in ES; Group C = 1-hour immersion in ES + 10,000 brushing in ES; Group D = 1-hour immersion in ES + 10,000 brushing in reference slurry (RS); Group E = 10,000 brushing in ES + 10,000 brushing in RS. The amount and pattern of dentin loss were determined, and the surfaces were observed using noncontact profilometry.

結果:

WT（pH5.0）は1回のブラッシングでRSより象牙質の喪失が少なかったが，1時間浸漬後の象牙質の喪失はRSより有意に大きかった．CAS1，CAPBおよびWTを塗布した試料では，ブラッシングまたは浸漬後の象牙質喪失パターンがU字型であったのに対し，RSを塗布した試料ではくさび型であった．

RESULTS: The WT (pH 5.0) caused lower dentin loss than RS after a single brushing cycle; however, the extent of dentin loss after 1 hour of immersion in the WT was significantly greater than that in the RS. Among the specimens treated with WT, a significant difference in dentin loss was observed between Group C and Groups D and E (P< 0.05) but not between Groups D and E. The surfaces exposed to CAS1, CAPB, and WT exhibited U-shaped patterns of dentin loss after brushing or immersion, whereas a wedge-shaped pattern was observed in those that underwent brushing with the RS.

臨床的意義:

過酸化水素とクエン酸を含むホワイトニング歯磨剤を従来の歯磨剤と併用した場合の効果（象牙質磨耗）は、従来の歯磨剤を単独で継続使用した場合と同様であった。

CLINICAL SIGNIFICANCE: The effects (dentin abrasion) of a whitening toothpaste containing hydrogen peroxide and citric acid when used in combination with a conventional toothpaste were similar to those seen with the continuous use of a conventional toothpaste alone.