Some people with CMT have trouble holding a toothbrush. Look around the WWW. There are many devices that will hold the toothbrush for you and just slip over your hand - no grip is needed. There are also devices to hold dental floss, dispense toothpaste and even squeeze the tube for you.

Flossing is easy of you just wrap a long piece of floss around your index fingers. Make it three feet long if you have to. The lack of pinch between index finger and thumb can be made up by simply wrapping the floss on your index fingers and then flossing. Floss can be rinsed and reused of you really don't like throwing out three feet of it every day. The idea with flossing is to simply disturb any plaque between your teeth. When you disturb it, it doesn't harden. Sure, it is good to get rid of as much of it as you can but that's what appointments to have your teeth scaled are for. You do the best you can and your dental hygienist does the rest. Don't forget to brush your tongue as well.

Some people with CMT use an electric toothbrush and just love it. You don't need strong hands or strong wrists to hold an electric tooth brush and they are getting smaller and lighter all the time. Just make sure that the one you select is easy for you to turn on and keep on and turn off. You shouldn't have to have your finger on the "on" switch all the time.
Weak hands or not, there is no excuse for not brushing or flossing you teeth.

Talk to your dentist if he suggests a dental bridge to take the place of extracted teeth bridge. Because of weak hand and a loss of finger dexterity you may not be able to get the bridge in and out of your mouth. Most dentists can figure out a way for the bridge to be easy to slip in and out. Don't be afraid to speak up.