thanks for posting your question on Just Answer
The reason for the foul odour may be
1)either related to the infected tooth
2)food stuck in between the tooth (where the bacteria ferment the food particles and produce sulfur like smell)
the smell from an infected tooth that needs a root canal is totally is different from the smell that is produced by food.
Tooth decay usually does not produce any smell,
I would suggest you to try this product
this is now available at walmart but at a lower concentration than the link i have posted below
I would strongly recommend using this product, if it is problems
with your gums this will surely take it awayhttp://www.therabreath.com/productdetail.asp?cat=1&pid=73
also remember that the smell in the mouth is related to the bacteria present in the mouth.
70 percent of those 750 million or so reside on your tongue so clean your tongue 2 or three times a day
and follow the instructions on therabreath
I am certain it will give you the much needed relief