歯磨きのときは歯茎も優しく磨きましょう。
When brushing your teeth, gently brush your gums as well.
alveolar lateral flap
Standard kanji spelling for gums.
Mixed kanji-kana spelling; common in everyday writing.
Compound of 歯 (ha, 'tooth') and 茎 (kuki, 'stem'), with rendaku voicing of the second element. The reading はぐき is a straightforward combination.