Why don't you ask your vet for Hill's t/d food?  It is made for cats that
have a problem with tarter.  Most vets carry it.  By the way, have you tried
kneeling on the floor, putting your cat between your legs and holding him
firmly with your legs (but of course not too hard)?  Use your left hand to
pull the left side of his lip up and do the top row with your right hand.
Forget opening the mouth to get to the bottom; it's usually too hard to get
too and that's when the cat starts to really squirm.   Then do the right side.
That's how I do it and it works well.  I also use a tiny bit of chicken
flavoured pet toothpaste from the vet's.

Do you feed her a dental dry food??  It helps mine but I still get their dental
appointments.  I mix the dental about 1/2 and 1/2 with their regular dry food.

My furbabies

http://users.ameritech.net/lestark/

I feed my 11 year old Burmese 'Hills Oral Care', has perfect teeth and no
tartar at all. Whiskers Duck n Liver in the morning and a bowl of biscuits
available from 3pm. That's his total diet - perfect weight and healthy.

Hello,

     I started using Hill TD every second day because it is apparently good
for teeth but I don't use it everyday because it makes my cats fat. Also I
give can food everyday because it is good for their health (it has a lot of
water) even though it is less good for teeth. Unfortuantely it seems that
nobody has heard about that thing that is put in the water to keep clean
teeth.

                  Richard