I think the concern would be if you need a local anaesthetic to have the fillings done? Maybe talk to your Dentist and GP about it too. Although the dentist should have a good idea. I'd be a little concerned about having x-rays even if it is low risk. But your dentist might not even do them due to you being pg.

Before I knew I was pg I had an operation which included x-rays on my abdomen area etc, I would have only just been pg, probably 2 weeks. That scared me a bit, but I got as much info as possible, talked to the Dr etc which put my mind at ease. Plus seeing the scan with a healthy baby moving around also helped.