Pls try Dentist Yan Wing Wai, he is very good and patient esp to kids. My daughter and her schoolmates had some fillings done by him. His clinic is at Mongkok Grand Tower, and his number is 2729-1051.
I just had my scaling done last week, and it was perfectly ok, price for scaling is HK$350 which is quite average, but can't remember how much I paid for my daughter's filling