If you are in need of cavities repaired I suggest getting in touch with your local dental school. Once a year there will be a practical where students have to repair caveties on a patient, so they will often offer free cavity screening + repair to the public for these exams. When I went to one, they discovered a few very small ones that looked like they could get bad in the future and opted to just do them right then. Dental schools outside of this are probably the cheapest way to have competent dental work done especially if you are uninsured (payment plans will be very permissive too)