I'd go with the "Carbide grit" variety - it doesn't have teeth per se, but it's a metal base with a batch of carbide grains fused around the mouth. Advantage here is that, as the grits break off, they present another sharp edge - while the teeth would just get dull and they're Hell to resharpen.
That, and the carbie grit will hold up better than the teeth - shallower cut. It will take a little longer, but it should also last longer.
Don't forget to keep the cut flooded to clear the kerf and keep the tool cool. Any light machine oil will work (I buy the stuff I use to sharpen knives in job lots.)
Just out of curiousity - are you doing this to add lighting?
5-90