Sajjad Shamloo - Student Research Committee, Faculty of Dentistry, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Abdolmehdi Araghizadeh - Department of Endodontics, Faculty of Dentistry Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Zahra Mirshekari - Student Research Committee, Faculty of Dentistry, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Alireza Khalilian - Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Koorosh Nematpour - Student Research Committee, Faculty of Dentistry, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
Mahsa Moannaei - Department of Oral & Maxillofacial Radiology, Faculty of Dentistry Hormozgan University of Medical Sciences, Bandar Abbas, Iran

Background: Tobacco has been reported to have multiple negative effects on oral health. This study aimed to investigate the frequency of posterior teeth decay due to smokeless tobacco (ST).Materials and Methods: This cross-sectional study included consistent nas and tanbak users for more than ۲ years in Bandar Abbas, Iran in ۲۰۱۸-۲۰۱۹. General characteristics, including age, gender, education, occupation, income, residence, the number of family members, and smoking status, as well as the duration of ST use, the use of mouth wash, and the frequency of using dental floss and toothbrush, were recorded based on the study aim. All patients underwent complete oral examination and posterior teeth decay was noted based on the results. The surface of teeth with decay (lingual, buccal, mesial, distal, and occlusal) was recorded as well.Results: From ۱۵۰ patients evaluated in this study with a mean age of ۳۷.۹۵±۱۲.۰۲ years, ۱۳۶ (۹۰.۷%) cases were males. Posterior teeth decay was found in ۱۳۵ patients (۹۰%). The mean number of decayed posterior teeth was ۳.۳۷±۲.۵۸. The highest decayed tooth surface was the mesial surface (۷۸.۷%), followed by the occlusal (۷۷.۳%) and the distal (۷۶.۷%) surfaces. The binary logistic regression model revealed that the odds of posterior teeth decay were approximately ۴-folds higher in employed participants compared to the unemployed ones (OR=۴.۲۹, ۹۵% CI: ۱.۱۹-۱۵.۴۹, P=۰.۰۲۶). Overall, occupation, income, duration of ST use, number of family members, and dental floss use were able to predict posterior teeth decay with an area under the ROC curve of ۰.۷۸۷ (۹۵% CI: ۰.۶۷۱-۰.۹۰۲, P<۰.۰۰۱), the sensitivity of ۸۵.۹%, and specificity of ۶۰%.Conclusion: A very high frequency of posterior teeth decay was observed in patients with≥۲ years of ST use. Posterior teeth decay appears to be affected by a combination of factors such as occupation, income, duration of ST use, number of family members, and the use of dental floss.