4種類の歯列矯正用アライナー材料のATR-FTIR分析と1週間の応力緩和

ATR-FTIR Analysis and One-Week Stress Relaxation of Four Orthodontic Aligner Materials.

抄録

本研究の目的は、歯列矯正用アライナー材料の化学組成と応力緩和の違いを推定することであった。この研究では、CAM（Scheu-Dental, Iserlohn, Germany）、COP（Essix, Dentsply Raintree Essix Sarasota,FL, USA）、DUR（Great Lakes Dental Technologies, Tonawanda, NY）、ERK（Erkodent Erich Kopp, Pfalzgrafenweiler Germany）の4つの市販されている熱可塑性材料を使用しました。各材料の長方形のストリップをメーカーの指示に従って作成し，減衰全反射-フーリエ変換赤外（ATR-FTIR）分光法と応力緩和特性を調べた。1週間後の印加応力の減少（RAS）を推定し，有意水準0.05の一元配置分散分析によって統計的に分析した。すべての試料は，応力緩和試験の前後に，透過型偏光照明下で光学顕微鏡検査を行った。ATR-FTIR顕微鏡により，すべての材料がポリエチレンテレフタレートグリコール（PETG）でできていることが明らかになった。また，試験を行った材料間のRAS値には，6％～10％の範囲で有意な差は認められなかった（p≧0.05）。光学顕微鏡による観察結果では，すべてのサンプルで緩和試験中にせん断帯が発生していた。試験した材料は化学組成と弛緩挙動が類似しており，臨床的有効性に違いはないと考えられる。

The aim of this study was to estimate possible differences in the chemical composition and relaxation of orthodontic aligner materials. Four commercially available thermoplastic materials CAM (Scheu-Dental, Iserlohn, Germany), COP (Essix, Dentsply Raintree Essix Sarasota,FL, USA), DUR (Great Lakes Dental Technologies, Tonawanda, NY) and ERK (Erkodent Erich Kopp, Pfalzgrafenweiler Germany) were included in this study. Rectangular strips from each material were prepared according to the manufacturer's instructions and subjected to attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and stress relaxation characterization. The reduction in applied stress (RAS) after one week was estimated and statistically analyzed by one-way ANOVA at the 0.05 level of significance. All specimens were subjected to optical microscopy before and after stress relaxation testing under transmittance polarized illumination. ATR-FTIR microscopy revealed that all materials are made of polyethylene terephthalate glycol (PETG) while no significant differences were identified in RAS values among materials tested, which ranged from 6%-10% (p ≥ 0.05). All samples illustrated the developments of shear bands during relaxation testing according to optical microscopy findings. The tested materials illustrated similar chemical composition and relaxation behavior and thus no differences in their clinical efficacy are anticipated.