Salary lvl in Berlin is below the German average. Pretty much across the bank. On the other hand cost of living is still relatively low. Yes rents are increasing but are still much below other German big cities like Hamburg, Munich or Cologne and light years away from places like London, New York or Paris. BUT Food and general living expenses are really low still. Especially compared to the cities mentioned above. So even on a below average salary you can still make a decent living in Berlin.
Now as a dentist if your goal is the highest possible income you are much better of looking for jobs in what used to be "West Germany". So places located on the south and west of the country. The federal states most interesting to you should be Bayern, Baden Württemberg, Nordrhein-Westfalen, Rheinland-Pfalz.