Dear An_246866:
I understand your concern. I am a parent as well, and my kids are at about the same ages. It is often difficult to sift through the clutter of information available about raising children. However, dental, and health care are the ones that you MUST listen to the doctor. Each person's circumstances are very different and the opinions of your girlfriends, though important to you, are not always (most of the time actually) valid.
The issue here is actually of trust in your dentist. The word doctor does NOT mean health care worker. It means teacher! Some doctors are better than others in educating their patients. Unless you go to dental school, you cannot possibly know all that your dentist does, however, it is the responsibility of the dentist (and any other professional) to find out your needs and particular circumstances and tailor make a proper treatment plan. Your responsibility, on the other hand is to find the doctor who can do this for you.
If you have issues of trust with this current dentist, I recommend that you go and seek the advice of a Pediatric dentist, who can tell you exactly how long the teeth with the cavities are needed and if and when they should be treated.
If your child is in pain, it is usually too late to treat the tooth with a simple, relatively inexpensive filling. The cost of a baby root canal and crown are much more and are usually not needed if the cavities are treated early and properly. If you end up extracting teeth prematurely, you will end up with improper shifting of teeth and a very expensive orthodontic (braces) bill.
Dental treatment is NOT expensive compare to other unimportant items that we all are guilty of spending our money on. However, I am not in position to set priorities for anyone. It is an individual choice. Children are just a very expensive venture, period.
Please do not listen to uninformed girlfriends (unless they are dentists, of course) and go see a professional you trust. There are many trustworthy dentists out there who would love to treat your family with honesty and integrity.
Best of luck,
Dr. Zev Kaufman