Contact the
ADA for advice about your employment conditions.
If you want to change jobs - that is, change from being employed by one person
to being employed by someone else, that's not unusual,
even for visa holders (are you on a 457?).
In the alternative, if you want change from being an employee
to being in practice on your own account, then that's not so unusual either.
As to working as a dentist, contact
AHPRA to reassure yourself that you are properly registered (or registerable),
allowed to work as a dentist in Australia, and that there are no (previously unknown, or perhaps forgotten)
conditions on your Authority To Practice.
You might well be registered already and in that sense, good to go.
Check the details of your visa for any restrictions or special conditions relating to your right to work (as anything).
As above, don't worry too much about the Restraint clauses.
In the event of dispute, you are not likely to be denied the right to work in your field,
nor are they likely to be interpreted so as to protect a monopoly practitioner ("the only dentist in the village")
from fair competition in the market.