1. Dental Research Department, Postgraduate Dental Education Center, Örebro, Sweden;
2. School of Health and Medical Sciences, Örebro University, Örebro, Sweden;
3. Department of Radiology, Skaraborg Hospital Skövde, Skövde, Sweden;
4. Clinical Epidemiology and Biostatistics School of Medical Sciences, Örebro University, Örebro, Sweden