is dental acrylic dangerous when heated?
What do you mean by acrylic, if it is PMMA. Then be aware that when it is heated that it cracks with unusual ease into the monomer (MMA) which is a strong irritant.

I have (in a fume hood) taken lumps of PMMA and heated them in a test tube with a bunsen, if you distill the product out and then redistill it you can get very pure methyl methacrylate. I have found that if you heat some of this MMA with some AIBN then it will then reform the PMMA.