How much do the dental in Taiwan go up to? Expensive? Cheap?
Hello omochi! Welcome to forumosa! Please be more specific in your request so that the kind folk here can guide you in the right direction. 
a lot of dental is covered by national health insurance. Compared to north america at least, its all cheap here. some thing you still need to pay for like fake teeth, crowns etc. i got a metal crown done and in the end it was $6000 NT, but they had fancier more expensive options as well.
i also had custom mouth things to correct my crooked jaw, when i was in canada it was going to run me around $600 CDN, here it was free (except that small fee you pay whenever you see nay dentist for any reason).
We have a friend (Taiwanese) who lives in the USA and comes back just for dental because the cost to do it there and here is more than the plane ticket. In fairness her teeth are crap and probably need all kinds of work.
The crux of the issue–it’s cheap, but find someone who knows what they are doing. Eleven years in Taiwan (with regular cleanings etc.) resulted in a lot of trips to fix everything when we moved back to Vancouver.
Ya, that is true. It took me 4 years to find the dentist i now use. And he is excellent. Knowledgeable, careful and very good English. he has fancy wireless screen remote things and shows you on a computer monitor by your chair (swivels and all) what your issue is and what should be done…options cost etc. My teeth are painfully tiny, back in canada dentists always bitched about working on my teeth cause they are so small and clamps etc wont hold onto them. But he managed a root canal and crown, with almost no pain i might add. If anyone needs a good dentist in Pingdong city let me know 
he has another office up north somewhere too.
Other dentists are just scary bad here, I admit. But there are still good ones to be found.