To be very correct, you would say "Herr Professor Doktor LASTNAME".
In written communication, and when introducing someone, one uses "Sehr geehrter Herr Professor Dokter LASTNAME"
NB: In Germany one ALWAYS needs a doctorate, and a second doctorate called "habilitation", to be a professor.
The proper salutation for a doctor is doctor or professor depending on their title. In writing the short form can be used which will be Dr. or Prof.
The proper salutation in English for either a medical doctor or the holder of a Ph.D. is the same for either male or female. It is simply "Doctor".
In English, the salutation for a doctor, whether they are a medical doctor or the holder of a Ph.D. is the same for both male and female. It is Doctor.
Dean actually is the proper salutation. One could say: Dean Redmond, would you please sign this form? Alternatively you could just use the Dr. salutation or the Professor salutation if those are appropriate, which they generally are.
If being formal, he/she is referred to as doctor.
Dr. and Mr. Smith.
A dentist can either have a Doctorate of Dental Medicine (DMD) or Doctorate of Dental Surgery (DDS). The proper salutation for a dentist is Doctor.
vmrs
Dear Dr. [Last Name],
The proper salutation for a man who is a doctor is Dr. David Jones or you can say Mr. David Jones, M.D. either way is ok. If the Doctor is married: Dr. David Jones & Mrs. Jones.
The proper salutation to more than one doctor would be "Dear Doctors". A person can also list each doctor's last name after the word doctor. So if the names were Smith, Jones, and Arnold, the salutation would be "Dear Doctors, Smith, Jones, and Arnold".
probabaly just a mrs. would suffise