Is a dmd an oral surgeon?

Not Necessarily. A dmd is a dental degree and can refer to any general dentist or dental specialist. An oral surgeon has completed a specialty program (additional training beyond the dds/dmd degree). Some oral surgeons also have md degrees which make them dmd md or dds md.
DMD = DDS. DDS and DMD both dental degrees. Oral surgeon is DDS or DMD who has completed a residency in oral & maxillofacial surgery. Some have an MD also.
DMD. The degree of "DMD" simply means that person has graduated from dental school. It is no different than having a "DDS." An oral and maxillofacial surgeon has additional training beyond a DMD or DDS, and some oral and maxillofacial surgeons are conferred a medical degree (MD) as well. Hope that helps.
DMD oral surgeon. A dmd is a dentist. A dds is a dentist. They are both degrees conferred when you graduate from dental school. Some schools confer one or the other, although most schools now confer a dmd. Since an oral surgeon is a dentist, he would have a dmd degree.