Is do the abbreviation for doctor of orthography?

The abbreviation for 'doctor' is 'Dr. ' Note the full stop/period after the 'r'. In English Grammarm any Word that is shortened is ended with a full stop, irrespective of its position in the sentence.

The Word 'doctor' has it root in Latin and means 'learned man' ; NOT medical practitioner.

If an individual has been awarded a 'doctor of orthography', by an university , they would be decorated with 'Ph.D.' That is 'Philosophaea Doctorus'. Translated in from Latin into modern English it means 'A learned man who is a lover of wisdom.' The subject matter, 'orthography' doesn;t come into it.