. The baking soda absolutely. I can think of nothing that would prevent you from using the Dakin's 20 to 1 dilute bleach solution for two minutes , swishing it around your mounted prosthetic in your mouth that could harm it.
2 Would using bleach change the color of the ceramic teeth and the plastic? material the teeth are set in?
For the teeth, no. For the plastic, also no. Not at the concentration we are discussing.
3 I use a nightguard. It is made of hard plastic, but has plaque build up in places. What would your office recommend in so far as keeping it disinfected? Should I keep it in a bleach or baking soda solution?
Hmmmm.... Well, the only known chemical that will fairly safely dissolve plaque, without destroying the teeth or endangering the patient too much, is the Sodium Hypochlorite in bleach, and until you get under the plaque where the bugs like to hide, you really can't kill them all, I'd say you need to use the bleach judiciously on your nightguard until you've cleaned out the existing plaque. I'd do that with some slightly stronger dilution of bleach, maybe ten caps of water to one of bleach, with an old toothbrush and a toothpick and work at it by hand until I had it clean. Wear gloves with the stronger bleach because it does dissolve skin!
Once you've done that, store it in a baking soda bath. It'll be fresher to put in and you can stay ahead of the plaque build up on it by rinsing it once a week in the 20 to 1 solution. Remember that solution HAS to be made fresh every time. You can't keep it!