Orthodontic Research Center, School of Dentistry, Shiraz University of Medical Sciences, Qom Abad Blv, Ghasrodasht AV, Shiraz, Iran.
J Orofac Orthop. 2022 Sep;83(5):332-338. doi: 10.1007/s00056-021-00312-3. Epub 2021 Jun 25.
To investigate the effect of a tooth whitening agent on surface roughness, surface hardness, and force delivery properties of polyethylene terephthalate glycol (PETG) thermoplastic retainer materials of two different thicknesses.
PETG sheets (1 mm and 1.5 mm) were thermoformed over a 30 × 60 × 10 mm rectangular stone model. Surface hardness, surface roughness, and results of a three-point bending test were evaluated before and after treatment (5 h daily for 14 days) with a 15% carbamide peroxide home bleaching agent. Data were analyzed using an independent sample t‑test.
Exposure of PETG specimens to the bleaching agent for 14 days significantly reduced surface hardness and increased surface roughness of samples of both thicknesses. The magnitude of force at different deflection points decreased significantly in the 1.5 mm thickness specimens treated with the bleaching agent, but no significant change was observed in the specimens with 1 mm thickness.
Use of a home bleaching agent could have adverse effects on surface roughness and hardness of PETG materials leading to reduced survival time of thermoplastic orthodontic retainers.
研究一种牙齿美白剂对两种不同厚度的聚对苯二甲酸乙二醇酯（PETG）热塑保持器材料的表面粗糙度、表面硬度和施力传递性能的影响。
将 PETG 片（1mm 和 1.5mm）热成型在一个 30×60×10mm 的矩形石模型上。在使用 15%过氧化脲家用美白剂处理前后（每天 5 小时，共 14 天），评估表面硬度、表面粗糙度和三点弯曲试验结果。使用独立样本 t 检验对数据进行分析。
暴露于美白剂 14 天后，两种厚度的 PETG 标本的表面硬度显著降低，表面粗糙度显著增加。在经漂白剂处理的 1.5mm 厚样本中，在不同挠度点的力值显著降低，但在 1mm 厚样本中未观察到显著变化。
家用漂白剂的使用可能对 PETG 材料的表面粗糙度和硬度产生不利影响，从而缩短热塑正畸保持器的使用寿命。
