First, please get over the myth that wet food causes bad teeth. Dry food does nothing to clean the teeth, it's the same as you eating a pretzel thinking it will clean your teeth.
That being said, cats need dentals just like humans. So, if he has never had one, chances are he may have issues going on in his mouth that do need to be addressed. FORLS, resorptive lesions, plaque and tartar buildup etc.
The only way for a vet to know is by taking xrays, doing a thorough exam and of course doing a dental.
I took my cats to a board certified dentist. I wanted to ensure the best possible care for my cats and the regular vet - doesn't take xrays, and uses drugs that I don't agree with. So, for peace of mind, I spent the extra money and took them to a dental specialist.
Whether you have the vet do it or you go the specialist route, make sure to ask:
1) what drugs do they use to induce (anesthesia) with?
2) what drugs do they use during/after the procedure?
3) do they monitor blood pressure?
4) do they take xrays before the procedure?
5) do they have experience with FORLS and removal of all part of the tooth and root?
6) what is their follow up care?
And remember do not allow metacam or ketamine. A good dentist will use something else and won't be offended by your request.
ketamin recall:
http://www.felinediabetes.com/phorum5/r ... ?8,1962009
http://news.vin.com/vinnews.aspx?articleId=14720
viewtopic.php?f=3&t=2482
and metacam is considered black label for cats and should never be used. Do people use it for their cats, yes, but they do so with the understanding of the dangers of the drug.
Also, if the vet suggests a dental without anesthesia - run don't walk away
http://www.felinediabetes.com/phorum5/r ... 8833,89077
Here is a link to a thread I started a year ago when going down the path of dentals. You may find this helpful in making sure you know what to ask, look out for etc.
viewtopic.php?f=29&t=5390