My Mom with dementia seems to have food left in her mouth long after she has finished a meal or snack. Any suggestions?

Patrice said that her mother eats better if Patrice just concentrates on the feeding.

Studies have shown that "attentive feeding" generally results in better eating. Of course, the fact that the caregiver will always have no other distractions is unrealistic, but still attention matters and this attention while feeding counts as close interaction which likely explains Patrice's mother's response.

The genuine support you give each other always makes me smile.
Carol

my 81 year old seems to be functioning ok but when she eats there is a lot of food left in her mouth hours after. It is all caked around her teeth, in front of her bottom lip and in her cheeks. It I say anything she gets quite nasty but then I will see her putting the chewed food into her hand and then on the table hours later. I really don't know to do about it .... or just leave her be... she is not the most pleasant with me at all.

It's not a problem unless the food sitting there causes tooth decay. It might be a symptom of dry mouth, which is a side effect of many medications. Encourage her to drink lots of water, and swish around water & spit it put to clean her mouth after eating (or brush teeth). Otherwise just ignore it, only Hollywood folks need to look perfect.