Funding for this research was provided by:
Medical Research Center, Oulu University Hospital and University of Oulu, Finland
Received: 27 January 2021
Accepted: 30 September 2021
First Online: 13 October 2021
: Data were collected with the permission of the register keeper, Oral Health Section, the City of Oulu, Finland, permission number 153§, Drno SOTE: 1550/045/2006. For a practice-based retrospective follow-up study of this kind, no statement from the ethical board is required when analyses are carried out without identification. Permission was granted by the register keeper before data acquisition. All identification details were stripped from the data before analysis. For this type of study, formal consent is not required. The ethical standards are in line with the Ethical Committee of the Northern Ostrobothnia Hospital District.
: There are no contradictions for publishing the work.
: None of the authors declare any competing interests as for this work.