Jassim, Sura D., and Lekaa M. Ibrahim. 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): 128-33. https://doi.org/10.12816/0033223.