Extraction of 4 pre molars for braces. is this really necessary?

Depends: If your orthodontist is correctly trained, has spent time to diagnose your individual problem with care, then it is perfectly acceptable to remove the first premolars. In doing a full work-up they have decided this will give you the best esthetic and functional results. There are "gray" areas, and if you are unsure, seek another opinion. We orthodontists are not offended by this, nor should we.

Depends on a case: In some cases extracting premolars is necessary due to severe crowding or protruded teeth.

YES - depends: Actually, extraction treatment is supported by vast scientific literature as superior when the removal of teeth is warranted (typically patients that have significant crowding and/or protrusion. Expansive treatment, on the other hand, often demonstrate the least stability. Seek an opinion with a licensed orthodontic specialist for your particular needs.

Ortho Extractions: It is all in the planning. If you agree that the orthodontist has done thorough diagnostic tests and explained why you need extractions, then proceed. My wife had ortho as an adult and resisted extractions. The ortho tried, but could not go beyond a certain point until i extracted four biscupids. She got a great result.