I went to one dentist. The cleaning experience is as many have reported: they took my X-ray, and dentist did the cleaning using the electric cleaner drill (?) I was in and out in 20 minutes for the whole thing. In LA, the cleaning lasts for close to an hour.
I wonder if there are any good dentists in 竹北市 or close by, that would actually take the time to clean out all plaque and even polish afterwards?
Though I already have NHI, I am willing to consider paying extra cash if I can find a good dentist.