The Effect of Irradiation Time and Distance on the Microhardness of Three Commercial Nanohybrid Resin-Based Composites - Jafarzadeh-Kashi, Tahereh; Hajihasani, Maryam; Heidari, Soolmaz; Khoshroo, Kimia; Masaeli, Reza; Tahriri, Mohammadreza (Frontiers in Biomedical Technologies, 2014)