Why can't an orthodontist or dmd or dds do the same thing as the general dentists?

They can: Any dds or dmd can do any dental procedure that he or she is comfortable doing and properly trained for. Specialists choose to limit their practice.

Legal reasons: An orthodontist is someone who first went to dental school, but continued on for additional training in a specialized field. An orthodontist providing general dentistry would need to advertise as a general dentist to avoid legal action. General dentists can perform specialty procedures, but they are held to the same standard of care as the specialist so many prefer to refer you to the specialist.

Training: An orthodontist has 3 more years of training in specifically orthodontics which is a very complicated field. A dds or dmd is a general dentist degree. Although a general dentist can perform orthodontics, their training is not to the level of an orthodontist. It is similar to a family practice physician delivering a baby. They can do it legally, but an obstetrician is going to be safer.

They can: Orthodontists are dds's and therefore general dentists as well. They likely would not, however, because as an orthodontist that is what they do all day and they have not done general dentistry for many years. You want to choose providers who do what you need daily. A dentist for dentistry, an orthodontist for orthodontics, periodontist for perio issues-- and so on. Each has unique training.