If it is a puppy tooth that has been retain, the chances of it being abscessed are zero..they have almost no root and decay is not that common in young Yorkies...I have never had one with true decay...tartar causes most dental problems...under the tartar is usually a healthy tooth, but the tartar goes beneath the gums and causes infections, abcesses and tooth loss..
I would brush the tooth with baking soda and try to remove the food that is no doubt caught between the two teeth...if you see any inflamation or infection, I would see the vet..if not I would wait for a regular dental..I would not put one of mine under to remove one puppy tooth...I got some great minty, white chewable bones at Petmarts that really helps wih tartar...best wishes |