1. Department of Pediatric Dentistry, Hacettepe University, Ankara, Turkey
2. Department of Maxillofacial Radiology, Hacettepe University, Ankara, Turkey
3. Department of Biostatistics, Hacettepe University, Ankara, Turkey
4. Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Bern, Switzerland