People don't pick a dentist the way they pick a product. They are choosing someone to trust with their health, and often with their anxiety. So they look closely: how recent the reviews are, what the office looks like, whether the hours work, whether their insurance is accepted, how easy it is to book.
Meanwhile there are probably a dozen other practices within a few miles, some backed by corporate groups with large advertising budgets. Independent practices don't need to outspend them. They need to be easy to find, clear about what they offer and reassuring at every step from the search result to the appointment request.