Negahdari R, Rahbar M, Fakhrzadeh V, Eslami H, Akbari T, Bohluli S. Comparison of Proinflammatory Cytokine Levels in Gingival Crevicular Fluid around Dental Implants with Ceramic and Titanium Abutments. J Contemp Dent Pract 2017; 18 (9):831-836.