According to the latest (8 May 2020) MOH guidelines, dentists in private practice are not supposed to treat unwell patients with a history of close contact with COVID19 infected person(s).
This means that if you are showing signs and symptoms of an upper respiratory illness (may be mild to severe) AND you have been in close contact with a suspected case of COVID19, then your dentist will have to refer you to approved institutions (National Dental Centre or National University Centre for Oral Health (NUCOHS) for treatment.
If you are well, there should be no reason that you cannot be treated in private practice but it is better to call the clinic ahead of time to inform them of your situation. You may be seen as the last patient of the session to allow for more cleaning time in between patients.