Sorry to hear you are struggling so much with this. Needles are a big one and something that worries even people who wouldn't label themselves as phobic.
If you get your wisdoms out, then every one of them need so get anesthetized. This shouldn't be bad news as a skilled dentist will be able to do this gently and in a way that you won't notice how many times or which places exactly were covered.
The syringe used at the dentist looks a bit different than the usual ones you know from GP etc. The unfamiliarity with it makes people get more scared if they spot it. A sensitive dentist will know it and make sure to handle it silently and discretely in order not to scare you half to death.
The needles may seem a bit longer than you would hope - just think of how far in the back of your mouth your back teeth are, you would want a dentist to reach the needed spot easily, for the comfort of both of you.
Do you have a dentist you feel happy with? It is always a good idea to let your dentist know what scares you (either personally at a consult appointment or via letter or email if you wouldn't feel comfortable to talk about it in person) and if you have insecurities or questions, s/he should be happy to give you some explanations and put you at ease.
You didn't mention what exactly it is that scares you about the anesthetics, but you might find some useful information here:
https://www.dentalfearcentral.org/fears/needle-phobia/
Here is also something The Wand, an alternative to the usual way of anesthesia:
https://www.dentalfearcentral.org/help/technology/wand/
