Answer: you wear a vest because you dont want anything to get on your clothes just incase if like the x-ray machine breaks.
I have to wear a protective vest for x-rays when I got to the dentist for them to check and see if my over bite improved so that is why you have to wear a protective wear (just for the safety of others and yourself).
When the dentist takes an X-ray it uses a small amount of radiation which can be harmful to humans. The vest will protect to a certain extent the effect of radiation by absorbing the dangerous particles or molecules produced by the X-rays.
