Outside of the surgeon, the type of dentist that typically makes a lot more money than the rest is the general dentist. One of the reasons this might be so is because they generally have to know more areas than a dentist who is specialized. They are followed by prosthodontist, and orthodontists.
Oral and maxillofacial surgeons make more than the above dentists because in many countries they are doctors with a medical license. Doctors have to go through extensive training during and after their degree programs. Furthermore, after their degree programs, many medical professionals have to go through residency programs.
Typically, the more education that a profession requires translates to more income when the person graduates from university. This is also the case with the general dentist who has to be well-grounded in several areas and the dental surgeon who really is a doctor.