Firstly what is it you are scared of? Is it lack of control, judgement, pain? Think about what it is that scares you. When you get to the dentist tell them what it is thats worrying you, I always try my best to help dental phobic patients, and most of the time we can get treatment done together with very little need for sedation however it's so much easier if we can both know what it is that scares you. So I can reassure you, or adapt what I'm doing to help. You are always in control, they can't do any treatment you don't want and you can always stop treatment at any time.
The dentist absolutely won't judge, we have seen it all a million times, probably even that morning! They will only help. Even as above if we give you loads of advice this is only to help prevent problems in the future, which is especially great if you are dental phobic! It is not a judgment on the past only to help in the future.
I've honestly had the most terrified people come in, who won't even cross the threshold let alone sit in the chair who have left having root fillings, extractions, crowns. You name it. With some people it takes time and careful planning, some people find headphones with podcasts or audiobooks helpful. Some people like stress toys and fidget types things to play with. It's often about working out how you can best cope with treatment, and if you can't there's always sedation.
I'm a dentist and I'm really scared of needles, like petrified. When I have blood tests they have to hold me down, i cry and I'm a total mess. So I completely understand when people come in and they are anxious. I completely understand why people can put off coming to the dentist because I know how much it can take to go into a surgery when you are that scared. But I also know that you can do it! Go to the first appointment, it will only be a check up, some x-rays. Then you can find out what needs doing and make a plan best suited to you! Good luck OP