...please please please urge him to go now.... I broke half a tooth last year and because it didn't really hurt I ignored it...then the filling came out...then some more of the tooth came away...then I had terrible abcesses and constant pain..... it took me a further 3 months to find an n.h.s dentist, and a further 6 weeks for an apointment to extract it... because it had crumbled so much it took her over an hour to extract it....she was fantastic, no pain atall....I was just slightly shell shocked afterwards... you could try and find a sympathetic dentist who specializes in nervous patients.....( I used to work for such a dentist who ran a private practise but did take referals from nhs dentists for nervous patients)
...mind you if it is only chipped it could be repaired if the decay hasn't spread too much, I personally would rather have it removed..."once the rot sets in " as they say....
...good luck and tell him to take his mp3 player along, as often it's the sounds of the dentist's tools that are off putting....