Mouth bacteria degrade protein meals into nitrate which decreases oxygen availability (metheglobulinemia). This should improve after you clear the protein from the mouth. If you're not sure note whether a stuff nose clear after mouth cleaning.
I had severe problems with nasal congestion, which improved a lot after turbinate reduction surgery. However, I didn't notice that that my nasal congestion has anything to do with my dental hygiene. Maybe I should have brushed my teeth more LOL