Peter Elbe, Monisha J, Sylas V P, George Suja Ani
Department of Orthodontics and Dentofacial Orthopedics, Government Dental College, Thrissur, Kerala, India.
Department of Orthodontics and Dentofacial Orthopedics, St. Gregorios Dental College, Ernakulam, Kerala, India.
Am J Orthod Dentofacial Orthop. 2025 Jan;167(1):39-46. doi: 10.1016/j.ajodo.2024.08.011. Epub 2024 Oct 2.
Used clear aligner trays are often indiscriminately disposed of with general plastic waste and incinerated. This study aimed to analyze the smoke composition from incinerating 2 common aligner materials: glycol-modified polyethylene terephthalate (PET-G) and polyurethane.
Each of the 2 materials in triplets was thermoformed. The thermoformed trays were shredded and subjected individually to open-fire combustion, ignited using a methane torch, in a specially designed combustion chamber. The resultant smoke was collected and analyzed using gas chromatography-mass spectrometry to study its in-depth composition.
A total of 20 peaks, corresponding to 20 compounds, were identified from each of the 2 material samples. O-xylene (21.06%) showed the maximum concentration in the PET-G sample, whereas 1,4-dimethyl-1,3-cyclohexadiene in polyurethane (18.88%). The first peak in the PET-G sample corresponded to benzene with a relative concentration of 5.18%. Four compounds were common to both samples: 1,4-dimethyl-1,3-cyclohexadiene; 1,3-cyclohexadiene, 2,3-dimethyl-; 1-hydroxymethly-4-methylenecyclohexane; and cyclohexanemethanol, 4-methylene-.
Benzene, a group 1 carcinogen, was identified in the PET-G smoke sample, whereas tetrahydrofuran, a suspected carcinogen, was found in the polyurethane sample. Some compounds were hazardous, whereas most were skin, eye, and respiratory irritants. Possible mitigation strategies include proper case selection, efficient manufacturing, direct 3-dimensional printing, and developing biodegradable materials. Clinicians can set up 'used aligner collection points' to ensure responsible disposal. Proper disposal guidelines and stringent regulations are the need of the hour.
使用过的透明矫治器托盘常常被随意当作普通塑料垃圾丢弃并焚烧。本研究旨在分析焚烧两种常见矫治器材料——二醇改性聚对苯二甲酸乙二酯（PET-G）和聚氨酯——所产生烟雾的成分。
将两种材料各制成三个样本进行热成型。把热成型后的托盘切碎，分别在一个专门设计的燃烧室中用甲烷喷枪点燃进行明火燃烧。收集产生的烟雾，并用气相色谱-质谱联用仪进行分析，以研究其详细成分。
从两种材料样本中各鉴定出总共20个峰，对应20种化合物。邻二甲苯（21.06%）在PET-G样本中浓度最高，而1,4-二甲基-1,3-环己二烯在聚氨酯样本中浓度最高（18.88%）。PET-G样本中的第一个峰对应苯，相对浓度为5.18%。两个样本中有四种化合物相同：1,4-二甲基-1,3-环己二烯；1,3-环己二烯，2,3-二甲基-；1-羟甲基-4-亚甲基环己烷；以及环己烷甲醇，4-亚甲基-。
在PET-G烟雾样本中鉴定出了1类致癌物苯，而在聚氨酯样本中发现了疑似致癌物四氢呋喃。一些化合物具有危险性，而大多数是皮肤、眼睛和呼吸道刺激物。可能的缓解策略包括合理选择病例、高效制造、直接3D打印以及开发可生物降解材料。临床医生可以设立“用过的矫治器收集点”以确保妥善处置。当下需要适当的处置指南和严格的规定。
