In 1988 Professor Zimmer graduated as DMD and Dr. med. dent. at the Free University Berlin/Germany. After 2 years in private practice, he was assistant Professor at the Philipps University Marburg (1990-1991), the Free University Berlin (1991-1994), and the Charité, Medical Faculty of the Humboldt University Berlin (1994-1997). In 1994, he graduated in Dental Public Health. In 2000 Professor Zimmer completed his graduation as "Privat-Dozent" in Operative and Preventive Dentistry. In 2001 he was Visiting Scientist at the University of Kansas in Lawrence (Prof. J.J. Hefferren). From 2003 to 2006 Zimmer was Deputy Head, Dept. of Operative and Preventive Dentistry, at the Heinrich Heine University Duesseldorf and until 2008 Acting Head of the same department. From 2008 until now, he is Full Professor and Chairman of the Dept. of Operative and Preventive Dentistry, Head of Dental School and Vice-Dean of the Faculty of Health, Witten/Herdecke University.