Introduction
The epidemiological findings reveal that smoking harms various health conditions such as cardiovascular and lung disorders and periodontitis in many adult humans. However, about 35% of men and 22% of women in developed countries smoke tobacco [11]. Some studies suggest that smoking increases caries risk. Smoking has been identified as a significant risk factor for periodontal disease and accounts for more than half the cases in the population [4]. The side effects of tobacco smoking on the periodontal bone have been demonstrated in several cross-sectional and longitudinal studies [27, 31]. On this basis, it was assumed that smoking might be a risk factor for apical periodontitis, but no suggestion of a possible link between smoking and apical periodontitis or endodontics in general [22]. Thus, this study evaluates the relationship between periodontitis and tobacco use by panoramic radiography in Bandar Abbas City, Iran.
Materials and Method 
The Ethics Committee approved the protocol of the Dental Faculty of Bandar Abbas City, Iran, and each subject signed a consent form after being advised of the nature of the study. A total of 198 panoramic radiographs were classified into periapical healthy (n=99) and periapical apical (n=99) groups. The photographs were collected from the radiology department of the dentistry college of the Bandar Abbas University in 2019. Radiographs were assessed by the radiologists for the subjects who met the criteria of this study as periapical healthy or control who has no radiographically detectable periapical lesion in any teeth and periodontitis or case as a patient who has at least 1 radiographically detectable periapical lesion in a tooth. The inclusion criteria were the quality and length of root filling treatment (RFT), the number (NoRFT), and inadequate root filling treatment (RFTin), and the exclusion criteria were total teeth numbers (TTN), age, gender, the cigarette and hookah use, and dental debris. In total, 24 men and 75 women average of 35.8 years old, were and 25 men and 74 women average of 35.9 years old, were the control. Data were analyzed by SPSS software v. 23, and Chi-Square, t-test, and logistic regression tests were used. 
Results
The TTNin the periodontitis was less than the control group (P<0.05). Cigarette, hookah smokers, and RFTin in periodontitis were higher than in the control group (P<0.01). Dental plaque, age, number of smokers, RFT, and NoRFT, did not differ between groups. Tobacco, hookah use, and RFTin were higher (P<0.05) in females in periodontitis. There were no gender differences in other variables. The most significant group and gender differences (P<0.01) were found in cigarettes, hookah, tobacco, and dental plaque (Table 1). 


Logistic regression analysis was used to determine the effect of tobacco (cigarettes and hookah), smoking, hookah, tooth plaque (yes, no), TTN, RFT, NoRFT, RFTin, age, and gender on periapical status (lesion, no lesion). The Odds Ratio (OR) was for NoRFT (39.7), RFTin (36.8), hookah (8.1), tobacco (6.57), cigarettes (3.59), tooth plaque (63.6), TTN (0.98), RFT (1.4), NoRFT (7.7) and RFTin (36.8), All variables show the effect on periapical tissue (P<0.01) but not age and gender. By removing age and gender, the TTN index will also be ineffective. The highest OR among smoking variables belonged to hookah, and dental indices were NoRFT (Table 2). 


Table 3 shows cigarettes and hookah affected TTN, age, and sex (P<0.01).


Removing age, sex, and TTN means increasing the number of smokers; the TTN will also decrease. Cigarettes or hookah do not affect tooth plaque, RFT, and NoRFT.
Discussion
The people who used tobacco and hookah in the periodontitis were more significant (P<0.01) than the control group, which means smoking could be associated with periodontitis. These are consistent with Lopez-Lopez’s [11] and Correia-Sousaa’s [15] findings but not with Rodriguez’s [18] and Balto’s [19] reports. The TTNin in the control group was higher than the periodontitis (P<0.01). The periodontitis had 2 fewer teeth than the control group, which is consistent with the Bukmir [16] results. Dental plaque did not show a difference between the groups, but the logistic regression evidence revealed a high Odd Ratio (6.63) shows its effectiveness. No study was found to confirm these results. 
This study showed that TTN, RFT, and other dental indicators are significantly effective in apical periodontitis. The reported papers did not confirm the tooth plaque, but smokers had 2 fewer teeth than non-smokers and had more RFT [16]. These results were also found by Segura-Egea [28, 30] and Krall [31]. 
The logistic regression analysis showed that age had no significant effect on periodontitis. This means the probability of having a periapical lesion will not increase with age. This finding is inconsistent with reports by Moszczynski [32] and Bukmir [16], who cited the effect of age on periapical lesions, and Hirsch [33], who reported the relationship between age and dental disorders in smokers. The reason for the age difference of this study from others is probably the low age variation of the study population (35 years old); therefore, it needs further investigations with the older participating population. 
Smoking hookah, tobacco, and cigarettes negatively affected periapical tissues. The low TTN, high dental plaque, and RFT were probably the effects of tobacco smoking on the periapical tissues. Age and gender were not related to the periapical lesions.

Ethical Considerations
Compliance with ethical guidelines
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)

Funding
This article is taken from the second author's PhD dissertation in the radiology department of the School of Dentistry of Hormozgan University of Medical Sciences, Bandar Abbas.

Authors' contributions
The 1st author: Idea, conceptualization, reading photographs, the 2nd: research method, collecting samples, analyzing, writing, and final reviewing.

Conflicts of interest
The authors of the article do not declare any conflict of interest.
 

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