I should think this is a question that varies from country to country. In my own country we can get reduced cost/free dental treatment if we go to a National Health dentist and are under 18 or on a low income. If you go to a private dentist the costs are very high.
Many people here spread the cost by taking out a payment plan and paying monthly installments. I don't know if this would be available where you are but it makes it much more affordable than if you have a huge amount coming out of your account in a lump sum.
Of course keeping your teeth healthy is the best way to ensure you don't need a lot of treatment so regular and thorough cleaning plus 6-9 monthly checks would probably be the best way of saving money because a problem would be caught early which would save having costly dental treatment later when you might need fillings or extractions.