I did a lot of research on r-Alpha lipoic acid before I started taking it. I do not recall seeing anything like what you are talking about. I ended up taking 1200 units (600 units morning and night) for just over two years. It had no impact on my fillings, and I have several.
The main thing if you are going to take this supplement is to make sure that you are taking R-ALA and not the product called alpha lipoic acid that is not preceded by the letter R. I do not recall all the differences, but they are significant. If you are not taking the R-ALA there may be some issues like you are talking about. I have no idea since I did not use that product.
What I do know is that this supplement did help in reversing my neuropathy. I could see some small relief from the beginning. That is a very good antioxidant. And, all of my doctors were quite supportive of me taking it. Including my retinologist.