I strongly believe it is unethical for general dentist to advertise him/herself as a ADA recognized specialty provider unless they have completed postgraduate course of study leading to certificate level recognition.   There is absolutely no mechanism other than an ADA Specialty residency to assure minimal educational requirements to provide competence in one’s area of specialty.  I don’t have a problem with a general dentist “limiting” themselves to a specific area of practice as long as they clearly disclose themselves as a general dentist.