Quote Originally Posted by jkingrph View Post
I have not reserached the dental application/reason for not using cyanoacyrlate vs metylacyrlate. Possibly inside a crown the cyanide group would be contained and cause dental nerve problems. The metyl group apparently lacks the toxicity.
In as many words, yes the methyl group lacks the toxicity. The main reason methacrylate is not going to be toxic is similar to cyanoacrylates. The monomers polymerize so quickly they don't have a chance to really do anything.

The LD50 for cyanide, determined from KCN which is readily dissociated into K+ and CN-, is about 5mg/kg or about .4g/180lb person. Of course the toxicity of superglue will depend on the ability for the CN group to break off of the actual molecule.