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  Background: Mandibular premolars, because of high anatomic variations, are among the most difficult teeth for root canal treatment.The aim of this study is to compare and evaluate root canal morphology of mandibular first premolars between males and famales in an Iranian population applying CBCT imaging.

  Materials and Methods: In this analytical-cross sectional study, 230 CBCT imaging belonged to 115 males and 115 females were evaluated in this study. Images were assessed in the three spatial planes and the difference in the number of canals and roots were compared and reported statistically. Data were analyzed using SPSS 17 software and Chi-square test.The significance level was set as p<0.05.

  Results: In total, of 460 mandibular first premolars, 85.7% had one root, 14.3% had two roots, 63.9% had one canal and 36/1% had two canals. In comparison between two genders, in the males the prevalence of one root was 78.7%, two roots 21.3%, one canal 60% and two canals 40%. In the females, the prevalence of one root was recorded as 92.6%, two roots 7.4%, one canal 67.8% and two canals 32.2%.

Conclusion: According to the results of this study the number of roots in the mandibular first premolars in males was statistically more than in females.

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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.