According to the Royal Society of Chemistry, superglue is not recommended for use on or in the body, including for denture repair. Cyanoacrylate, the active ingredient in standard superglue, releases formaldehyde and acetic acid when it dries. These ingredients can cause chemical burns and should not be consumed.
A great alternative to superglue is a denture repair kit. It can be purchased for $7 to $12 at major retailers, and it contains an adhesive that is safe for the human mouth. While it is not meant to be a long-term solution for broken dentures, it can provide denture wearers with an economical temporary fix.
Dermabond is a medical adhesive used to seal cuts in place of stitches. It would also be appropriate for denture repair because it contains octyl cyanoacrylate, which is a nontoxic version of cyanoacrylate.