So my son went for his twice a year checkup at the dentist the other day, and they did x-rays for the first time. To my great horror, they showed 3 cavities. One was worse than the others. Obviously, I feel like a horrible, horrible mother. I thought we were doing a good job with brushing and flossing, but I guess not.

I've really tried to limit juice and sweet drinks and whatnot as well. Oh well. At least I know that what we're doing isn't working and we have to change things up a bit.
Anyway my question is, has your child had fillings? We love our pediatric dentist and she's been great so far. She says she tends to do fillings for little kids with nitrous oxide only because the novacaine injections and numbness freak them out and upset them, and that many kids can get by with just the gas. Obviously I'm pretty nervous about this approach. She says she'll use his reaction as a gauge, and give him novacaine if he needs it. I worry that by then he'll already be in pain.

We went for his 5 year old well-child visit and the pediatrician was NOT in favor of this plan. She thought it was unnecessary to fill baby teeth when they're going to fall out anyway. And that doing a procedure without pain meds was cruel... "Would you undergo a dental procedure without novacaine?" She's afraid it will lead to dental phobia.
I've been researching online and there's a lot of stuff that says you SHOULD fill these teeth, but a lot of the sources are from the Pediatric Dental Association and other parties that may have a bit of bias.
BTW, these aren't back back molars... these are the first molars on the bottom that are next to the four front teeth.
Would love to hear anyone's input!
Re: Fillings for 5 year old with cavities??
You did make the correct choice and see a pediatric dentist, though. Sometimes general practice dentists (and not all, but some) just don't have the patience to deal with squirmy little kids in their chairs. I remember one little one took up 3 appt slots and STILL wasn't finished because he would wiggle or cry.
Some fillings don't need to be numbed to perform them. It depends on the person and how close to the nerve the cavity is. (Which is why pediatric dentistry is available-they specialize in children!)
And don't be hard on yourself, mama! Sometimes it's just genetics. I have never had a cavity but my little brother has had fillings since he was probably the same age as your little one. He just has really deep grooves in his teeth where things can sit. All you can do is try!
If you really want some research- learn about cavities turning into root canals. And periodontal disease. Those little teeth make a huge difference!!!!
I don't really think it's cruel. Gas is just another form of pain management. A injection hurts! I think my 6 yr old would be far less freaked out by gas.