Jassim, S. . . D., & Ibrahim, L. . . M. (2016). Correlation between Periodontal Health Status and Salivary Matrix Metalloproteinase-9 Levels in Smoker and Non-Smoker Chronic Periodontitis Patients (A Comparative Study) . Journal of Baghdad College of Dentistry, 28(4), 128-133. https://doi.org/10.12816/0033223