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Background and Aim: Chronic periodontitis is the most prevalent form of periodontitis and it generally considered as a progressive inflammatory disease. Environmental and systemic factors can alter the immune response to biofilm and lead to progressive degenerative disease. Chronic periodontitis is defined as an infectious disease that causes inflammation in the tooth-supporting tissues, periodontal attachment loss, and bone loss. Identification of risk factors for this disease is important. Hence, this study aims to evaluate the risk factors for chronic periodontitis.
Methods & Materials: This case-control study was conducted on 120 periodontitis patients and 120 healthy controls in Arak, Iran. A questionnaire was used to estimate their Socio-Economic Status (SES) and survey demographic and risk factors. For the diagnosis of chronic periodontitis, the identification of plaque accumulation site and clinical examination were performed. To investigate the association of chronic periodontitis with study variables, multilevel logistic regression analysis was used in STATA V. 11 software. 
Ethical Considerations: This study obtained its ethical approval from the Research Ethics Committee of Arak University of Medical Sciences under code: 1397.145.
Results: The Odds Ratio (OR) of chronic periodontitis in adults aged above 30 years was 2.91 (95% CI: 1.01-8.73). Compared to subjects with low SES, the OR of chronic periodontitis was 2.28 (95% CI: 1.22- 4.27) in those with moderate SES and 0.89 (95% CI: 0.79-0.98) in those with high SES. Compared to patients who did not brush their teeth, the OR of chronic periodontitis was 0.67 (95% CI: 0.39-0.89) in patients reported toothbrushing. Compared to those who reported changing toothbrush sooner than 3 months, the OR was 4.96 (95% CI: 2.27-11.3) in those their changed their toothbrush for more than 6 months interval. The OR of chronic periodontitis in current smokers was 3.09 (95% CI: 1.52-4.76).
Conclusion: Cigarette smoking, alcohol consumption, tooth brushing, and SES are the risk factors associated with chronic periodontitis.

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Background and Aim: The research results show tobacco use increases cardiovascular and lung disorders or the probability of periodontitis in humans, while no definitive relations were yet confirmed. This study evaluates the relationship between periodontitis and tobacco use by panoramic radiography in Bandar Abbas City.
Methods & Materials: A total of 198 panoramic radiographs were classified into periapical healthy (n=99) and patient (n=99) groups. Radiologists assessed radiographs for periodontitis via Total Teeth Numbers (TTN), the quality and length of Root Filling Treatment (RFT), the number (NoRFT), and inadequate root filling treatment (RFTin), age, gender, the cigarette and hookah use, and dental debris. Data were analyzed by Chi-Square, t-test, and logistic regression.
Ethical Considerations: Due to the lack of therapeutic intervention and the preservation of patients’ characteristics, ethical considerations are not included in this study (Code: IR.HUMS.REC.1399.384)
Results: Tobacco, hookah use, TTN, and RFTin were different (P<0.01) in groups, but cigarette smoking, debris, RFT, NoRFT, and age were not. Women in the periodontitis group showed high (P<0.01) in tobacco, hookah use, and RFTin, while no gender differences were observed in other parameters. The logistic regression results showed that based on the Odd Ratio NoRFT (39.7), RFTin (36.8), `hookah (8.1), tobacco (6.57), debris (3.62), smoking (3.59), RFT (1.4) and TTN (0.89) were the highest (P<0.01). At the same time, age and gender did not affect periapical tissues. 
Conclusion: Hokka, tobacco, and cigarette use negatively affected the periapical tissues, respectively. The decrease in TTN and increase in debris and RFT were probably the effects of tobacco smoking on the periapical tissues. Age and gender were not related to the periapical lesions.