Department of Orthodontics, University of Kentucky, Lexington, 40536-0297, USA.
Angle Orthod. 2010 May;80(3):554-61. doi: 10.2319/042809-232.1.
To investigate whether oral cleansing agents affect the essential work of fracture (EWF) and plastic work of fracture (PWF) for two types of orthodontic thermoplastic retainer materials.
Polyethylene-terephthalate-glycol (PETG; Tru-Tain Splint) and polypropylene/ethylene-propylene rubber (PP-EPR) blend (Essix-C+) sheets were compared. For each material, six sets of 25 sheets were thermoformed into double-edge-notched-tension specimens; subsets of five specimens were formed with internotch distances (L) equal to 6, 8, 10, 12, or 14 mm, respectively. Sets were stored (160 hours, 25 degrees C) in air (DRY), distilled water (DW), Original Listerine (LIS), mint Crest ProHealth (CPH), 3% hydrogen peroxide (HP), or Polident solution (POL). Specimens were fractured in tension at 2.54 mm/min. Areas under load-elongation curves were measured to determine total work of fracture (W(f)). Linear regressions (W(f) vs L [n = 25]) yielded intercepts (EWF) and slopes (PWF). Ninety-five percent confidence intervals were used to evaluate differences in EWF and PWF estimates.
PP-EPR blends showed higher EWFs after storage in HP vs storage in DW. PP-EPR blend showed higher EWFs after storage in CPH vs PETG. After HP storage, PP-EPR exhibited lower PWFs than with any other storage conditions. PP-EPR exhibited higher PWFs than PETG after storage in DRY, DW, and LIS.
Compared with DW, none of the cleansers decreased the energy to initiate fracture. With one exception, no cleanser decreased the energy to continue plastic fracture extension. In PP-EPR blend, increased resistance to fracture initiation was observed with CPH and HP, yet, surprisingly, HP decreased resistance to plastic fracture growth.
研究口腔清洁剂是否会影响两种正畸热塑性保持器材料的基本骨折功（EWF）和骨折塑性功（PWF）。
对比聚对苯二甲酸乙二醇酯-乙二醇（PETG；Tru-Tain Splint）和聚丙烯/乙烯-丙烯橡胶（PP-EPR）共混物（Essix-C+）片。对于每种材料，将 6 组 25 片分别热成型为双边切口拉伸试样；其中 5 个试样的亚组的切口间距（L）分别为 6、8、10、12 或 14mm。将各试样组分别在空气（DRY）、蒸馏水（DW）、原始李施德林（LIS）、薄荷味佳洁士 ProHealth（CPH）、3%双氧水（HP）或保丽净溶液（POL）中储存（160 小时，25°C）。将试样以 2.54mm/min 的速度在张力下断裂。测量载荷-伸长曲线下的面积以确定总断裂功（W(f)）。线性回归（W(f)与 L[n=25]）得出截距（EWF）和斜率（PWF）。使用 95%置信区间评估 EWF 和 PWF 估计值的差异。
PP-EPR 共混物在 HP 储存后 EWF 高于 DW 储存。PP-EPR 共混物在 CPH 储存后 EWF 高于 PETG。在 HP 储存后，PP-EPR 的 PWF 低于任何其他储存条件。PP-EPR 在 DRY、DW 和 LIS 储存后 PWF 高于 PETG。
与 DW 相比，清洁剂都不会降低起始断裂所需的能量。除了一个例外，没有清洁剂会降低塑性断裂延伸所需的能量。在 PP-EPR 共混物中，发现 CPH 和 HP 会增加断裂起始的阻力，但令人惊讶的是，HP 会降低塑性断裂生长的阻力。
