Why does someone with a vp shunt need antibiotics during wisdom teeth extraction? what about if they're not dependent on the shunt anymore?

When you have an : Indwelling foreign body, you want to protect it from infection. During a tooth extraction, antibiotics are administered to reduce the risk of the surgery causing bacteremia and a subsequent infection of your shunt and brain and meninges.

Endocarditis: Any surgical repair of congenital malformations of the heart require antibiotics prior to any dental procedure according to american heart association guidelines. If the shunt is still present bacteria from your mouth can get introduced into your blood stream during dental work and the bacteria may attach to the shunt and cause infection inside your heart.

Probably not : The data is pretty cleat that otherwise healthy individuals who have longstanding implanted devices get no demonstrable benefit from antibiotic prophylaxis. This is a changing viewpoint and not enough science has been developed to comment on all cases. Often the doctor will prescribe antibiotics out of an "abundance of caution". I would confer with your surgeon.