My dentist tells me to make sure to brush the gums, gumline and tongue to get all the bacteria.

Also a side note, I have basically no enamal on my teeth (combo of genetics and drinking lots of soda for years) and my dentist says I have microfissures (sp?) in my teeth. Basically microscopic holes all over my teeth with no enamal to protect them, and it causes me to be very sensitive to hot/cold stuff. So something like that could cause problems also. As well as the above mentioned sinus problems.