R.,
I am a dental hygienist, so I have a little bit of experience in this area. A child at two is probably a little young to be switched to regular toothpaste, especially if he cannot spit yet. The problem with adult toothpaste is the fluoride, which is great in small amounts, but can actually cause fluorisis (white mottled areas on teeth) if swallowed at a young age while teeth are still developing.
I would also encourage you to keep brusing your child's teeth for him. Let him do it first, but then go back and get the back teeth and the inside of the teeth especially. Children do not have the fine motor skills to effectively brush their teeth. I once heard a dentist say that until a child can write in cursive, they really can't be expected to control a toothbrush in fine detail.
If you are worried about breathe, see if you can brush his tongue. A lot of breathe issues can come from plaque on the tongue, and postnasal drip from sinuses. When you brush his tongue don't tell him to stick it out, leave it in the mouth and just try and gently get back as far as you can without gagging him. Good Luck!
Oh, I have to add one more thing for all parents...please, please, please watch how much juice, candy, and soda your children are having. A soda has about 10 tsp of sugar, and a ph of about 2. Even diet soda has a low ph b.c of the carbonation. Believe it or not, even with the advancements of fluoride and sealants we are seeing little kiddos with mouths full of huge cavities as early as 2 years old. children needing root cananls in baby teeth and chrome steel crowns. It breaks my heart to see these little ones have negative experiences at the dentist from an early age when most of the problems could have been prevented.