My tooth is solid in place and there is a sulcral of 4mm, i am being told. he wants extraction since it is greater than 3mm. x rays only show pocket.

No I don't think so: Having a pocket of 4mm is not a reason to lose a tooth. An x-ray will show bone loss, not gum pockets . Having no symptoms of pain or infection is another reason not to remove a tooth . More diagnosis must be done before extraction . Question your dentist's decision . Ask more questions..Get more answers!

Communication Error: The situation you pose in your question dosen't make sense. There must be more factors in the decision to extract then you have given here. More likely its that there is a misunderstanding of the diagnosis between your doctor & you. Before any treatment you should resolve this misunderstanding or get a second opinion before going ahead.

Second opinion: The sulcus is the space between the tooth and gums. 1-3mm is considered healthy. 4mm means there is some inflammation and possible pocket formation. That alone would not be enough reason to extract the tooth. I would recommend getting a second opinion.