After doing a little research, since I'm not an expert on teeth...
A pontic is basically an artificial tooth held in place by a, usually, removable brace or fitting. The pontic is the actual tooth substitute, whereas there are many ways that they can be fitted. These can take the form of: Fixed Bridge. (Google source)
I'd much prefer non plural. That is the word that pops up far more, from what I've seen. Googling "pontics" its all "top 5 pontic designs", pontic this and that. The plural is also used, but so be it. For the plural...if you achieve a 4 figure level, hat off to you (hope you do)