Hi, L.!
I was a daycare teacher and have worked with children at various developmental stages. There is the typical advise, keeping a teething ring that she likes there at the daycare center that is hers and leaving a tube of orajel with a signed permission slip for application. It could be that her mouth is just annoying her but not enough for her to cry out in pain.
We had a girl that was between 18 to 20 months and just the cutest thing. When she was happy and content. However, she did have that nasty biting thing. We also had this little boy, right around 16 to 18 months, that was the same way. Eventually, this lead to a couple more of the kids biting back to defend themselves.
We, as teachers, kept a log of the biting activity. It consisted of Name of Biter, Activity that was going on, What the child was doing at the time of bite, day and time of bite and how the situation was handled and the teacher that handled the situation. We couldn't write it down on the log and we couldn't disclose it to the biting child's parents(privacy issues), but we also kept track of which child it was in our heads. It helped us learn what the triggers of this behavior was, what actions we as teachers needed to take as well.
As for Disciplinary actions being used, it is hard to say. We used a firm NO! Showed them that it hurt the child that they bit and the child was crying, showed them the red mark that was left behind from the bite and then re-directed the child to something else. And as we started learning the patterns and triggers, we were able to redirect before it would happen. This generally worked for most of the children after a period of time. Then they grew out of it.
Personally, I would ask your daughter's daycare teacher &/or director of the center to do something similar if they are not already and have a meeting to go over it with you. You may want to keep a log at home as well. I would definitely find out how they are disciplining her, maybe you know of a better way that works for her. Together you will be able to develop a plan.
Good Luck!