Perbedaan kedalaman poket dan resesi gingiva pasien periodontitis kronis perokok dan bukan perokok: studi retrospektif di klinik integrasi RSKGM FKG UI periode 2010-2015 = The difference of pocket depth and gingival recession between smokers and nonsmokers chronic periodontitis patient: a retrospective study in klinik integrasi RSKGM FKG UI 2010-2015