Department of Orthodontics and Dentofacial Orthopedics, Bapuji Dental College and Hospital, Davangere, Karnataka, India, 577004.
Clin Oral Investig. 2024 Apr 3;28(4):240. doi: 10.1007/s00784-024-05640-3.
Thermoplastic polymers show alteration in their mechanical properties after thermoforming on a dental model. The purpose of this in-vitro study was to evaluate the tensile strength of different thermoplastic polymer sheets thermoformed on a pre-treatment (moderate crowding) and post-treatment (well-aligned) maxillary model of a patient.
Forty maxillary models (Twenty Pre-treatment & twenty Post-treatment of uniform dimension) were made by duplicating them using alginate Hydrogum 5 (Zhermack). Samples were then divided into eight groups of 5 samples each. The thermoplastic sheets Imprelon® (Scheu-Dent), AVAC R® (Jaypee), Placa Crystal® (BioART), EZ-VAC® (3A Medes)-1.0 mm thick were thermoformed on these models respectively. The sample was retrieved using ceramic bur mounted on a straight hand-piece and subjected for testing using TINIUS Olsen 10ST micro universal testing machine and recorded.
There was no statistically significant difference (P > .05) in tensile strength of thermoformed thermoplastic polymer sheets between pre-treatment and post-treatment maxillary model. Tensile strength of EZ-VAC (3A Medes) showed higher variation between pre-treatment and post-treatment maxillary model though it was found to be statistically insignificant (P > .05). Significant difference (P < .05) was seen between groups when they were compared separately among pre-treatment and post-treatment models.
Placa Crystal (BioART) among the pre-treatment group, EZ - VAC (3A Medes) among the post-treatment group, showed highest tensile strength.
Results of the study highlights the necessity to test materials in conditions which stands in accordance with the clinical scenario to a considerable extent and also emphasizes the need for further study in aligner.
热成型在牙模上后，热塑性聚合物的机械性能会发生变化。本体外研究的目的是评估在患者上颌模型的预处理（中度拥挤）和后处理（排列整齐）条件下热成型的不同热塑性聚合物片的拉伸强度。
使用藻酸氢凝胶 5（Zhermack）复制 40 个上颌模型（20 个预处理和 20 个后处理的均匀尺寸）。然后将样本分为 8 组，每组 5 个样本。分别将 Imprelon®（Scheu-Dent）、AVAC R®（Jaypee）、Placa Crystal®（BioART）、EZ-VAC®（3A Medes）-1.0 毫米厚的热塑性片热成型在这些模型上。使用安装在直手机上的陶瓷钻头检索样品，并使用 TINIUS Olsen 10ST 微万能试验机进行测试并记录。
预处理和后处理上颌模型之间热成型热塑性聚合物片的拉伸强度没有统计学上的显著差异（P>.05）。EZ-VAC（3A Medes）的拉伸强度在预处理和后处理上颌模型之间表现出更高的变化，但统计学上无显著性差异（P>.05）。当单独比较预处理和后处理模型中的组时，发现组之间存在显著差异（P<.05）。
在预处理组中，Placa Crystal（BioART），在后处理组中，EZ-VAC（3A Medes）表现出最高的拉伸强度。
研究结果强调了在与临床情况相当程度上相符的条件下测试材料的必要性，并强调了在矫正器中进一步研究的必要性。
