I’ll tackle the inscriptions. In this case, it helps if you have some knowledge of Greek, and Greek numerals.
It reads as follows: ARPA ΑΘΗΝΑΙ αϠξγ
The ΑΘΗΝΑΙ part is easiest. This is the ancient Greek word for the city of Athens (not the goddess Athena, although she’s depicted on the medal too).
αϠξγ are Greek numerals, here appearing in cursive form. Each letter stands for a particular numerical value. The second numeral may look like π, but is actually sampi, an archaic Greek letter. Together, the letters symbolize 1000 + 900 + 60 + 3 = 1963. The mark just to the upper right of α should really appear on the lower left, to show 1000 instead of 1.
Now we can figure out ARPA. This may be the former organization ARPA Internationale. The acronym stands for “Association pour les recherches sur les parodontopathies” (Association for Research on Periodontal Diseases). This organization held their 17th congress in Athens in 1963. So I’m guessing the medal is from that convention.
