1. Faculty of Medicine, Research Unit of Oral Health Sciences, University of Oulu, Oulu, Finland
2. Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland
3. Department of Stomatology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
4. Faculty of Medicine, Department of Obstetrics and Gynecology, Oulu University Hospital and PEDEGO Research Unit, University of Oulu, Finland
5. Faculty of Medicine, Infrastructure for Population Studies, University of Oulu, Oulu, Finland