Purpose : The aim of this study was to evaluate the bleaching efficacy and safety of a hydrogen peroxide-based pre-filled tray-type at-home bleaching agent. The color stability after bleaching was also investigated.

  Materials and Methods : The product used for the clinical trial was Opalescence Go (OPG), an at-home bleaching agent manufactured by Ultradent Japan. OPG is applied in trays pre-filled with bleaching gel. The main component of the bleaching gel is 6% hydrogen peroxide. A total of 20 participants performed at-home bleaching with OPG.

  The changes in tooth color before and after bleaching were evaluated using intraoral photographic documentation and a colorimeter. Side effects regarding tooth sensitivity, gingival irritation, and gingival chemical burn during the bleaching period were investigated. Additionally, color reversion 12-18 months after bleaching was evaluated.

  Results : The mean color difference (ΔE) immediately after 10 days of home bleaching for 90 minutes per day was 6.5, and the score difference was 4.0 when evaluated using the VITA Classical Shade Guide. After 12-18 months, the mean ΔE was 5.0 and the score difference was 2.9. There was no significant difference in the mean ΔE before bleaching and 12-18 months later (p>0.05), but a significant difference was observed in the mean value difference (p=0.046).

  Discussion and Conclusion : OPG is a safe bleaching agent, but mild and transient hypersensitivity was frequently observed ; therefore, it is important to explain the risks of tooth bleaching to patients. Slight color changes were observed 12-18 months after bleaching.

  Purpose : This retrospective study examined the effect of home bleaching in five patients concurrently undergoing orthodontic bracket treatment. We also examined whether there was a difference in color tone between the brackets and the surrounding enamel after the brackets were removed. After bracket removal, we performed home bleaching again to examine its effectiveness and usefulness for orthodontic patients with brackets.

  Materials and Methods : The subjects were five patients who underwent home bleaching (HW₁) with Opalescence Go (OPG) during orthodontic treatment with brackets, followed by bracket removal and further home bleaching (HW₂) with OPG. OPG is a bleaching material applied via pre-filled trays. The main component of the bleaching material is 6% hydrogen peroxide. The changes in color tone before and after bleaching were evaluated by spectrophotometric and visual colorimetric methods. We also examined whether there was a difference in color tone between the tooth surface to which the brackets were bonded and the surrounding tooth surface.

  Results : The mean color difference (ΔE) on the incisal or cervical side before and after HW₁ was 4.3 (±1.7), and before and after HW₂ was 5.5 (±1.7). The mean ΔE at the crown center after before and after HW₂ was 4.8 (±1.6). Before HW₂, the mean ΔE between the incisal side (Inc) and the crown center (Bon) was 3.2 (±1.2), and the mean ΔE between Bon and the cervical side (Cer) was 3.0 (±0.9). After HW₂, ΔE_Inc-Bon was 2.9 (±0.3), and ΔE_Bon-Cer was 2.9 (±0.7). The mean difference in score between pre-bleaching and HW₁ was 2.6 (±0.6) and the mean difference between pre-bleaching and HW₂ was 4.7 (±1.5).

  Discussion and Conclusion : Home bleaching with 6% hydrogen peroxide in pre-filled trays was performed on orthodontic patients wearing bracket devices, and a noticeable improvement in color tone was observed. After bleaching, there was a slight difference in color tone between the bracketed area and the surrounding area.

 目的：異なる歯と肌の色を組み合わせた男性モデル顔から受ける印象評価を行い，肌に調和する歯の色を検討した。

 方法：男性モデル顔に，歯（0M1，A1，A3，A4）と肌（青白，美白，標準，小麦）の色を組み合わせた16種の画像を，一般成人男性30名（平均30.3±7.8歳）が評価した。

 結果：歯と肌の色が最も調和したのは，青白肌は0M1，美白，標準，小麦肌はA1であった。すべての肌の色で，見た目年齢は明度の低い歯の色ほど高かった。因子分析の結果，3因子（外面的魅力，職務遂行能力，内面的魅力）が抽出された。3つの因子を満たす肌の色に適した歯の色は，青白肌は0M1とA1，美白，標準，小麦肌は0M1，A1，A3であった。

 結論：肌の色に調和する歯の色は，肌の色と同一，または類似のトーンの調和関係にあり，肌の色よりも明度の高い歯の色であった。職務遂行能力は，明度の低い歯の色ほど低く，男性は明るい歯の色ほど職務遂行能力が高いと考えていることが認められた。