The effect of adjunctive low-dose doxycycline and licorice therapy on gingival crevicular fluid matrix metalloproteinase-8 levels in chronic periodontitis - Farhad, S Z; Aminzadeh, A; Mafi, M; Barekatain, M; Naghney, M; Ghafari, M R (Dent Res J (Isfahan), 2013)