My cats mouth

Question
We have a 2 year old rescue cat called Misty who seems to have problems with her mouth.  When we first got her she had sore gums for which the vet treated her for Gingivitis.  This has since cleared up. We have, however, noticed that she has problems picking up small treats and the like, most of the time she just gives up.  Also her mouth hangs slightly open most of the time, as though her jaw doesn't quite meet. Is this likely to have been caused by some kind of previous trauma do you think, or would you have any other suggestions.  When she eats the complete foods such as Iams or Hills, she doesn't pick the biscuits up individually the same as our other cat.  Instead she kind of scoops them up in her mouth by pushing them across the dish.  It doesn't seem to give her any pain, more the fact that she seems to get fed up trying.
Any ideas?  

Answer
She may have feline resorptive (or neck) lesions on her teeth that may be causing her some discomfort in chewing.

I did have a patient with a similar problem and he ended up having Toxoplasmosis.

She may have had some trauma before for which you may want to consider having an x-ray of her jaw taken.