Objectives

First, to analyse the in vitro release of BPA and Bis-GMA from an orthodontic resin composite (Transbond XT, 3M Unitek), stored in various conditions, by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS); then to extrapolate the data to the clinical situation. Secondly, to explore the thermal stability of Bis-GMA.

Methods

Cylinders of resin composite were prepared and stored according to 3 different protocols: (1) they were light-cured 20 s, then placed in artificial saliva; (2) they were light-cured 2 s, then placed in acetonitrile; (3) they were light-cured 2 s, then placed in methanol. For each group, BPA and Bis-GMA release were determined with GC/MS and/or LC/MS at least after one week. Besides, 120 brackets (10 of each type) were bonded over metal teeth, then debonded, and the weight and the surface of resin composite residues were measured. BPA and Bis-GMA release of adhesive residues were extrapolated from the data obtained with the cylinders. Besides, BPA release from a heated Bis-GMA solution was measured.

Results

With GC/MC, BPA was detected in all samples. With LC/MS, BPA was detected only from samples immersed in MeOH; Bis-GMA was detected, in varying amount according to the extraction media and the light-curing time. BPA was found after heating of the Bis-GMA solution.

Significance

Contamination risk and the heat applied in GC/MS may overestimate the BPA release from resin composite. Based on the LC/MS results, the risk of BPA release after orthodontic bonding would be more than 42 000 times lower than the TDI for a 30-kg child.

中文翻译：

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正畸树脂复合材料中双酚A的释放：GC / MS和LC / MS研究

目标

首先，通过气相色谱/质谱（GC / MS）和液相色谱/质谱法分析储存在各种条件下的正畸树脂复合材料（Transbond XT，3M Unitek）中BPA和Bis-GMA的体外释放（ LC / MS）；然后将数据外推到临床情况。其次，探讨Bis-GMA的热稳定性。

方法

根据3种不同的方案制备和存储树脂复合材料的气瓶：（1）将其光固化20 s，然后放入人工唾液中；（2）将它们光固化2秒，然后置于乙腈中；（3）将它们光固化2秒，然后置于甲醇中。对于每组，至少在一周后用GC / MS和/或LC / MS测定BPA和Bis-GMA的释放。此外，将120个托槽（每种类型的10个托槽）粘结在金属齿上，然后脱粘结，并测量树脂复合材料残余物的重量和表面。BPA和Bis-GMA释放的胶粘剂残留物是通过使用圆柱体获得的数据推断得出的。此外，还测量了从加热的Bis-GMA溶液中释放出的BPA。

结果

使用GC / MC，可在所有样品中检测到BPA。使用LC / MS，仅从浸入MeOH的样品中检测到BPA；检测到Bis-GMA的量不同，具体取决于提取介质和光固化时间。加热Bis-GMA溶液后发现BPA。

意义

污染风险和GC / MS中施加的热量可能会高估树脂复合物中BPA的释放。根据LC / MS结果，对于30公斤的儿童，正畸粘接后释放BPA的风险将比TDI低42 000倍以上。