Dentist lacked professional courtesy and was rude! What do I do? :-(?

that sounds like a really uncomfortable (literally) situation! I am sure he wasn't totally surprised when you returned and told him you werent happy -not only with the LOOKS of it but also the fact it had caused sores in your mouth. trust me, i worked for a dentist for over 15 years and they are trained to know what does and does not look good so...he had to partially know there was a good chance you would not be pleased/ maybe his ego was alittle inflated and he wanted you to think it wasnt HIS problem but YOURS! but....if I were you i would return with the expectation that you will like the next one (and be relieved its thin and plastic not big scary metal ,lol) and just tell say..." thank you soo much for understanding..THIS is what I had expected" and just smile and remind him you have been a satisfied customer of his for along time...dont be embarrased or apologize though....