my understanding is that wolf teeth are the first premolars. They may need to be removed if they cause discomfort, for example by being rattled against bit. When depends on age of the horse and speed of maturity, on average between 5-6, but not all horses need to have wolf teeth removed.
The value of having a vet to attend for equine dentistry is that 1) they can give IV (intravenous) sedation if required, and 2) only vets may incise the gum tissue - Equine dental technicians can only extract the tooth.
Found a good website at www.poolhousevets.co.uk, search for dentistry - very informative site.
Hope this helps