Did your dental health suffer from breastfeeding?

I have been breastfeeding my son for one year - and at my last dental appt. (one yr. ago), my teeth were in pristine condition! I just went back to the dentist, and she said I have FOUR cavities and might need a root canal in a previously filled tooth! I was nearly hysterical - I have severe "white-coat syndrome" at the dentist from a traumatic childhood experience ...and I take very good care of my teeth to AVOID these kind of things from happening. I am wondering if nursing could have caused such an extreme shift in my dental health....HELP!
Also, I'm pretty freaked about the root canal thing, so if anyone out there can reassure me - I would be forever grateful! Thanks!

Contrary to the popular wives' tale, babies do not "take the calcium from your teeth".
Also, the tale that women lose a tooth for every baby is also untrue.
I don't think that breastfeeding has anything to do with your changes in dental health, rather, you have most certainly had a change in your life (an exciting and major one)
Whether you notice or not, your diet has probably changes. maybe a few more "on-the-go" type foods. You may have also been spending less time flossing and brushing your teeth, or may have skipped a few nights all together (I know I have).
One year is a long time to go between dental visits, which is why 2 visits a year is recommended.
Also, added stress can alter the way your body handles bacteria. What may be a sustainable oral environment can become alter and promote decay with just the change of a few foods, lack of sleep, and a little bit of stress.
As far as the root canal--this may not be due to new decay. sometimes it is better to crown teeth with older and large fillings while there is still a natural tooth and root to crown.
Or, if the old filling is large, and there is new decay, the risk of being able to fill a larger area without exposing vital nerves decreases.
If you don't agree with these dentist's findings, you can always get a second opinion; however, this is really not due to breastfeeding.

Do to lack of vitamins and nutrients, my mother have lost a lot of teeth when she was pregnant and nursing. I feel kind o guilty. :(

If you had morning sickness while you were pregnant, the stomach acid would have worn down your tooth enamel. Even though your teeth looked good a year ago it could be that the weakened enamel finally allowed you to get cavities. That happened to me. If that is the case, to help prevent it from getting any worse you might want to look into fluoride treatments or supplements. Also, avoid acidic foods as those can further wear down your enamel. Things like citrus, tomato products, vinegar, soda pop, and also alcohol. Your mouthwash might also have alcohol in it, if so, switch to ACT. (Some of the ACT brand does have alcohol in it now, but the original plain ones don't.) The thin enamel would probably be near your gums, so when you brush be sure to go up and down, and get under the gums. Back and forth will make it worse.

Good luck with your appointment. Have you tried having them also give you nitrous oxide (aka laughing gas)? When I have that it makes me sleepy and everything seems dreamlike and a lot less annoying. See if they can start giving you that way before the shots or anything. I was also wondering if having someone with you might help put you at ease? Hubby, friend, sister, etc.?