bad breath mouth

Tonight my son was 8 months old bad breath. Can I brush your mouth even though he has no teeth?
He has a tiny knot in a tooth is trying to appear. Apart from that, there's absolutely nothing there except the gums and tongue.
Can I brush your mouth? If so, what I can use?
made by Gerber and sell it at Walmart. your child toothpaste and comes with a rubber toothbrush that you slip on your finger. and you can use even if there arent teeth. its really recommend you do get rid of the formula.