How can I get over my fear of the dentist?

Ok so I'm absolutely terrified of going to the dentist. And because of that I haven't been for over 6 years. Now I have really bad decay on one of my front teeth, I've found (what I think is a large cavity) on my back tooth and I'm pretty sure I have quite a few other cavities.

Now even with all these problems and the fact that now it hurts to eat really hot or cold food. And I can't chew certain food on my right side because it hurts I can't bring myself to phone the dentist and make an appointment.

My mom thinks I'm being daft but she just doesn't understand. Just thinking about having to go sets me off crying or I will have a panic attack