Word of mouth & referrals is the best proven and effective way of marketing.
There are lots of different ways you can market your practice.
Create a website and make sure it is mobile friendly , Ask patients and colleagues for referrals , build a strong network in and around your area , focus on setting your practice apart from the other practices.
You can find some useful resources here which can give you more insights about the query.
You can find & access a short tutorial relevant to your dental business related queries here.