We've been using the "Medline Treated Suction Toothbrush Kit" that fits on the end of the suction tube to our DeVilbiss suction unit. It has a brush on one side of the head and a sponge on the other--works great for teeth, gums and tongue. They seem kind of expensive because they're disposable, but I use one for 3-4 days before tossing (just check the sponge before each use to make sure it's intact).
Our dentist also gave us a tool I can slip into my PALS's mouth on one side between molars and press on a lever that ratches it open so he doesn't have to hold his mouth open himself (and will keep his mouth from clamping shut if I get the tool in before it does).