title: Letter to the editor.
authors.affiliation: Periodontology Department, Faculty of Dentistry, Hacettepe University, Ankara, Turkey.
authors.forename: Huseyin Gencay
authors.identifier: 0000-0001-6695-2133
authors.initials: HG
authors.lastname: Keceli
authors.affiliation: Biostatistics Department, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
authors.forename: Anil
authors.initials: A
authors.lastname: Dolgun
authors.affiliation: Periodontology Department, Faculty of Dentistry, Gaziosmanpasa University, Tokat, Turkey.
authors.forename: Humerya
authors.initials: H
authors.lastname: Aydemir Turkal