You have less to worry about than you think going to the dentist in Tijuana, the area around the border in Tijuana has tons of good dentist. I am scared of going to the Dentist, the Dentist wanted to meet with me. He knew what to do, he also was able to talk English. I felt very good after meeting with him in person, very warm and personable guy.
You have about the same chance of having issues with your dentist in Tijuana Mexico as you do in the US, I have a tool that a dentist broke off in my tooth from a root canal done in Las Vegas, and it’s still inside the tooth!