He graduated from Istanbul University, Faculty of Dentistry, in 1995. Between 1995-2000, he worked as a research assistant at Istanbul University, Faculty of Dentistry, Department of Endodontics. In 2000, he received Dr. Med. Dent. degree. He worked at Yeditepe University, Faculty of Dentistry from 2000 to 2014. He became Assistant Professor in 2002 and Associate Professor in 2008. He began to work at Okan University, Faculty of Dentistry in 2014 where he became a Professor of Endodontics. He is the author of many published in local and international journals. He gives courses and conferences on root canal shaping and procedural problems in endodontics. Dr. Kayahan is a certified member of European Society of Endodontology. He is an Education Committee Member of the International Federation of Endodontic Associations. He is the president of Asian Pacific Endodontic Confederation and Turkish Endodontic Society.