Ceramics are also harmful, but as I said before, proper protocol and rubberdam. I think your wifes dentist was to generous with the adhesive. A dental adhesive is 100% liquid and because of that sensitive for accidents. They are also volatile, so if the apply this with a syringe ( not proper protocol)it can easely clog. Ceramics and composites usely are applied with a syringe but they are a lot thicker then adhesives/sealants. I have hundreds of scientific documents posted at my website. My blog is written in Dutch but al the info is English. I am not sure if I have info there about ceramics but I will have a look.