no it can not
Decay is a word for dead things/rot.
it will get its tooth in to a smelly discovery. it will lose some af its "SKIN".it will rot the tooth.
All acidic liquids can rot tooth enamel.
It doesnt rot teeth but disolves the enamel, enabling food sugars to rot the tooth much faster.
If it's sitting there in your mouth, then get it taken out because that can cause infection, bad breath, etc. Not to mention if it starts to noticeably rot, you're going to have a rotten tooth in you're mouth and that's pretty much disgusting.
It is a tooth that the root has been damaged and is "dead"
I'm thinking tooth paste will dry out. I don't think it can rot, I think you would be hard pressed to find a bacteria that can live in the base(opposite of acid) that tooth paste is.
Yes, a dead tooth can cause or trigger a headache.
Yes. It is caused by eating sweet/sticky foood and NOT BRUSHING TEETH PROPERLY.
Bury it
Yes, most dead bodies float for a period of time
for meh the plants