Is prolonged bleaching more harmful to dental enamel than daily dietary and hygienic oral habits?

Abstract The ultrastructural and mechanical properties of enamel surface were evaluated after prolonged bleaching treatments with 10% carbamide peroxide in the presence or absence of orange juice (erosive challenge) and toothbrushing (abrasive challenge). In total, 145 incisor bovine teeth were used in this study. Twenty-five samples were prepared for the ultrastructural evaluations, and 120 samples were prepared for microhardness and roughness tests. These 120 samples were divided into eight experimental groups (n = 15): G1- artificial saliva; G2- abrasion; G3- erosion; G4- dental bleaching; G5- erosion + abrasion; G6- bleaching + abrasion; G7- bleaching + erosion; and G8- bleaching + erosion + abrasion. All groups were tested at T0 (before treatment), T1 (14 days), T2 (21 days), and T3 (28 days). Two-way analysis of variance for repeated measures and the post hoc Sidak tests (p ≤ 0.05) were used. The roughness evaluation demonstrated an increase in damage for all experimental groups with an increase in the time period. For microhardness, the groups exposed to artificial saliva (AS) and abrasive challenge did not show any differences at any time points, while the other groups showed a decrease in microhardness from T0 to T3. Ultrastructural evaluation showed different surface alterations in response to the treatments. Despite prolonged bleaching periods, the procedure caused lesser enamel surface alterations than exposure to orange juice alone or in combination with brushing.

摘要 本研究评估了在存在或不存在橙汁（侵蚀性刺激）以及刷牙（磨耗性刺激）的条件下，经10%过氧化脲（carbamide peroxide）长期漂白处理后，牙釉质表面的超微结构与力学性能。本研究共使用145颗牛切牙。其中25份样本用于超微结构评估，120份样本用于显微硬度与粗糙度测试。该120份样本被分为8个实验组（每组n=15）：G1-人工唾液（artificial saliva, AS）；G2-磨耗组；G3-侵蚀组；G4-牙齿漂白组；G5-侵蚀+磨耗组；G6-漂白+磨耗组；G7-漂白+侵蚀组；G8-漂白+侵蚀+磨耗组。所有组别均在T0（处理前）、T1（第14天）、T2（第21天）以及T3（第28天）四个时间点开展检测。本研究采用重复测量双因素方差分析结合事后Sidak检验（p≤0.05）进行统计分析。粗糙度评估结果显示，随着观测时间延长，所有实验组的釉质损伤程度均呈加重趋势。在显微硬度方面，接触人工唾液（AS）以及仅接受磨耗性刺激的组别在各时间点均无显著差异，而其余组别从T0至T3的显微硬度均出现下降。超微结构评估结果显示，不同处理方式可引发不同的牙釉质表面改变。尽管漂白周期较长，但相较于单独接触橙汁或橙汁联合刷牙处理，该漂白操作引发的牙釉质表面改变程度更低。