Funding for this research was provided by:
School of Dentistry, Kermanshah University of Medical Sciences (95547)
Received: 17 October 2018
Accepted: 3 June 2019
First Online: 19 June 2019
Ethics approval and consent to participate
: This study was approved by the ethical board of Kermanshah University of Medical Sciences (IR.kums.rec.1395.575). All parents provided their informed consent in writing.
: Not applicable.
: The authors declare that they have no competing interests.