Can fillers on your nasolabial folds affect your lips and smile?

Well-placed filler will not negatively impact the smile, but improve support and symmetry. For nasolabial folds, I recommend a combination approach to get the most improvement. I recommend fillers for the folds themselves but also lifting around the mouth and cheeks to build underlying anatomical support. In our practice we combine sculptra with other fillers "layered" on top and lasers, rf treatments, J Plasma and peels to get the most conservative natural look. Please see a facial sculpting expert. Best, Dr. Emer

Yes, fillers placed in the nasolabial folds and piriform can certainly have an subtle effect on your smile, however, this tends to be a positive effect. The filler adds perioral support and can help evert the lip. 

This is a great question - there certainly are some subtle effects that fillers can have on the way muscles work, but this generally works to our advantage, in that if we treat an area where support/volume is lacking the effect on musculature is positive, and produces more normal muscle activity.
So to answer your question there is a possibility that the mouth corners may lift a little at rest, and lift less than you are used to on smiling.
Treating the naso-labial folds shouldn't project the lips - of course lip treatments themselves can do so.
If treatment is done sensitively and in keeping with your features you shouldn't need to worry about these concerns.
Best wishes,