"The chief problem, then, is transferring the food from the plate to the digestive tract. When one has braces, it tends to make a stopover on the front teeth.

Any cleaning up that can be done by the tongue with the mouth closed is legitimate. A quick scrape with the thumbnail in the mouth isn't legitimate, but if Miss Manners doesn't see you do it (the napkin goes up to the mouth with four fingers visibly holding it, so that it appears the lips are merely being wiped), it doesn't count against you. Serious picking with tools must be conducted away from the table. This is a nuisance, but it does give one the pleasure of having a second helping when everybody else's meal is over."