
Hi,
It's best if you don't make a big deal of it, and just gently handle her muzzle, not necessarily moving her lips, at all odd times of the day. Just say "teeth", touch her lips, praise and let go. Do this maybe 10 times a day, making sure you let go
before she starts objecting, and she'll relax about it. Fiddle gently with her mouth while you're watching TV and she's sleepy, etc. But as has been said, she is probably teething so her mouth may be sore.
:)