There is another Boston Dental Clinic in Duchondong, gangdong-gu, Seoul (SE, purple line 5), in between exits 3 and 4 on the 3rd floor. He earned his degree from Boston and made sure to clearly explain the issues with my teeth and what work he would do on them. He was pretty quick! Actually and orthodontist, but had to also do general practice when he came back to Korea.
I had cavities sealed recently. For back teeth, it's 100,000 KRW. For the smaller teeth, it's 80,000 KRW. Per cavity. Scaling was about 50,000 KRW, I think.