FAKTOR RISIKO KEPARAHAN GINGIVAL LEAD LINE PADA PETUGAS SPBU DI MEDAN : RISK FACTORS OF GINGIVAL LEAD LINE SEVERITY OF GAS STATION EMPLOYEE IN MEDAN. (2013). Dentika: Dental Journal, 17(3), 251-254. https://doi.org/10.32734/dentika.v17i3.1723