I am not real clear on the procedure you are having. However the dentist uses the needles to numb the area in which he/she will be working on so as to not hurt you. The pain you may have with the needle should be minor much like a prick it is fast and over with.
If you have a fear of needles then let your dentist know this a head of time. Dentist understand your fears of them and the tools they may have to use. If they know that you may have these fears they will take the time to make you feel more convertible with what they are doing. Maybe just making sure you do not see the needle will help you with that.
I hope this has help you