Received: 9 February 2018
Accepted: 8 June 2018
First Online: 13 July 2018
: Suwnnna Korsuwannawong is a senior researcher at the research office, Faculty of Dentistry, Mahidol University. Prof. La-ongthong Vajrabhaya is a Deputy Dean for Research Affairs, College of Dental Medicine, Rangsit University.
: The authors declare that they have no competing interests.
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