Negligence or just an unfortunate experience?

I had 4 small composite fillings in July, all minor surface fillings. I had no problems, pain, etc. with the teeth prior to the fillings. Three weeks after the fillings, I began to experience a lot of sensitivity and pain.

I got in to see my dentist, told him I was having severe sensitivity, and showed him where I was feeling pain, and explained that I was taking Advil every 4 hours, for 2 days. He proceeded to file the fillings down, told me it could not be a nerve/root problem because there was not any decay. No x-rays taken.

By the next morning, the whole side of my face was swollen. I immediately got a 2nd opinion from a new dentist, who did a thorough exam, x-rays. I then found out I needed 2 root canals due to trauma from the fillings, and had a bad infection.