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Year : 2022  |  Volume : 13  |  Issue : 2  |  Page : 36-39

Evaluation of Total Antioxidant Capacity in Al-Daura Oil Refinery Workers and Its Relation to Oral and Periodontal Conditions: An Analytical Cross-Sectional Study

1 Oral Diagnosis Department, College of Dentistry, University of Anbar, Al-Anbar Governurate, Ramadi City, Iraq
2 Poisoning Consultation Center, Ghazi Alhariry Teaching Hospital, Baghdad, Iraq

Date of Submission07-Mar-2021
Date of Decision10-Apr-2022
Date of Acceptance12-Apr-2022
Date of Web Publication12-Jul-2022

Correspondence Address:
Ahmed Makki A Al-Qarakhli
Oral Diagnosis Department, College of Dentistry-University of Anbar
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/denthyp.denthyp_33_21

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Introduction: Total antioxidant capacity (TAC) is an important marker to be measured to explore the effect of oil fume on oral tissue. This study examined the effect of longtime exposure to oil fume on oral and periodontal tissue. Materials and Methods: A total of 52 participants consisted of four groups of 13 participants each. Oral examination and periodontal indices were taken. TAC was analyzed. Results: The study groups showed highly significant differences in plaque, gingival index, and clinical attachment level (P < 0.001) compared to the control. The older workers have shown the highest total antioxidant capacity levels. The oil group has expressed a significant lowest total antioxidant capacity level (P > 0.05) in comparison to the control. Oral lesions including ulcerations and white and red patches were absent in workers. Conclusion: Total antioxidant capacity is an important biomarker in the diagnosis of oral and periodontal diseases.

Keywords: Occupational diseases, oil refinery, oral lesions, periodontal disease, total antioxidant

How to cite this article:
Al-Qarakhli AA, Hamid Mudher S, Mahmood Ali S, Yakub Majid A. Evaluation of Total Antioxidant Capacity in Al-Daura Oil Refinery Workers and Its Relation to Oral and Periodontal Conditions: An Analytical Cross-Sectional Study. Dent Hypotheses 2022;13:36-9

How to cite this URL:
Al-Qarakhli AA, Hamid Mudher S, Mahmood Ali S, Yakub Majid A. Evaluation of Total Antioxidant Capacity in Al-Daura Oil Refinery Workers and Its Relation to Oral and Periodontal Conditions: An Analytical Cross-Sectional Study. Dent Hypotheses [serial online] 2022 [cited 2023 Jun 5];13:36-9. Available from:

  Introduction Top

In oil refinery, exposure to oil compounds has the potential risk to cause various types of illness in the human body.[1] Absorption of approximately 52% of the inhaled compound, relaying on the concentration and the length of exposure to the oil.[2],[3] This may induce oxidative stress and is reported to alter the immune response.[4] In the oral cavity, there is a dental plaque that is composed of microorganisms. This situation may be accompanied by alteration of immune response and in the presence of a specific type of bacteria may lead to tissue destruction. The aim of this study is to examine the possibility of long-term effects of exposure to oil fume to induce oral lesions and aggravate periodontal disease. It has been hypothesized that exposure to oil fume could decrease the total antioxidant capacity (TAC) and enhance oral lesions and exacerbate periodontal disease.

  Subjects and Methods Top

This cross-sectional study was conducted in the Aldaura oil refinery in the south of Baghdad, which has multiple oil processing departments. The participants in this study were all male workers in these different departments. The study was approved and granted by the relevant ethical committee in the College of Dentistry at the University of Anbar. Written informed consent was obtained from all participants.

The whole workers were recruited from each department of the refinery to avoid bias in the sampling stage. They were asked to answer a questionnaire form, including name, age, gender, name of their departments, duration of work, and systemic diseases. Seventy-three workers participated in this study. Thirty-nine of them were eligible to fit the criteria of selection (have no hypertension, diabetes mellitus, and smoking) according to their answers.

The control group was examined from the neighbor area who didn’t work in the refinery. Thirteen participants were questioned and examined after signing a consent form.

A total of 52 subjects were participating in this study: 13 subjects as a control periodontitis group, 13 workers from the oil group, 13 from the oil pipe group, and 13 from the oil barrel construction group. The groups chosen for this study were exposed to the same environment and worked beside each other. These study groups included the following:

The oil group represented those who worked in the oil department, the oil pipe group involved those who worked in the oil pipe department, the barrel construction group represented those who worked in the department of barrels, and the control group was selected as a match to the study groups and they had periodontitis but they did not work or expose to oil products.

Saliva sample collection was carried out in March 2019 on three consecutive days in the morning after participants were instructed not to eat or drink anything except water for 1 hour.[5]

The oral examination was carried out, looking for oral lesions and periodontal health status of Ramfjord teeth using disposable dental diagnostic tools and William periodontal probe. Ramfjord teeth were examined[6] for plaque index (PI),[7] gingival index (GI), and[8] clinical attachment level (CAL).[9]

Determination of TAC levels in saliva was conducted using enzyme linked-immunosorbent assay (ELISA). TAC was assayed and quantified using human total antioxidant capacity ELISA kit (Shanghai YEHUA Biological Technology Co., Ltd, China). The assay procedure was done according to the manual instruction. A spectrophotometry plate reader (BioTek, Santa Clara, USA) was utilized to measure the TAC optical density values at 450 nm.

Statistical analysis

wOne-way ANOVA test was used to find the differences between groups followed by Tukey multiple comparisons post hoc. Pearson (r) correlation coefficient test was used to investigate whether there is an association between the indices PI, GI, and CAL with TAC levels in each group. A P ≤ 0.05 was considered a statistically significant difference. Analysis was performed by using SPSS software pro. V23 (IBM, Chicago, USA).

  Results Top

The oral examination has shown no oral lesions, such as ulcers, white and red patches, or oral mucosal infections. The mean age was 42.5 ± 11.3 (21–65) years. The data on TAC levels are presented according to the age groups There is a gradual increase in TAC levels alongside age. Older people have demonstrated the highest levels [Figure 1].
Figure 1 Mean and standard deviation of total antioxidant capacity distributed according to age groups

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The TAC levels in the oil group have demonstrated a significantly lowest level compared to the control group (P = 0.047, 95% CI –2.816 to –0.019). While other groups have shown nonsignificant differences in their levels in comparison to the control group [Figure 2].
Figure 2 Total antioxidant capacity levels among oil, oil pipe, barrel construction, and control groups. The oil group has significantly lowest level compared to the control group (P = 0.047, 95% CI –2.816 to –0.019)

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The TAC levels according to the occupational period have demonstrated nonsignificant differences between the below 20 years group and 20 years and more group (P = 0.377, 95% CI –2.027 to 0.786). The below 20 years group has shown the lowest TAC level ( Supplementary Figure 3).[19]

The mean PI has expressed significantly higher levels in oil pipe (P < 0.001, 95% CI 0.069–0.890) and barrel construction groups when compared to the control group (P < 0.001, 95% CI 0.265–0.757). PI in the oil group has shown nonsignificant differences (P > 0.05) (Supplementary Figure 4).[20]

The mean GI has demonstrated a significantly higher level in the oil group (P = 0.0001, 95% CI 0.449–1.295) in comparison to the control group. There are significant differences in the oil pipe (P = 0.0001, 95% CI 1.072–1.620) and barrel construction group (P = 0.0001, 95% CI, 1.066–1.579) when compared to the control group (Supplementary Figure 5).[21]

In regard to the mean of CAL, it has expressed a significantly higher level of oil, oil pipe, and barrel construction groups in comparison to the control group (P < 0.001, 95% CI, 2.357–3.843, 2.329–3.670, 2.720–4.048, respectively) (Supplementary Figure 6).[22]

The correlation coefficient (r) has shown a significant (P < 0.05) and a negative fair correlation (r = –0.61) between TAC and CAL in the control group, respectively (Supplementary Table 1).[23]

However, the overall correlation between TAC and the indices that have been carried out in this study have demonstrated nonsignificant differences (P > 0.05) regardless of the group types. TAC and CAL have expressed a negative weak correlation (r = –0.19) (Supplementary Table 2).[24]

  Discussion Top

TAC is an important factor to be measured in oil workers. It has been found to be affected by oil fume.[4]. In the case of periodontal disease, the bacteria will activate the host response mechanism, which in turn results in the activation of neutrophils. Neutrophils are the primary source of reactive oxygen species (ROS) in periodontitis.[10],[11] Therefore, a proper balance between ROS and antioxidants is very important to oral and body health.

Within this study, the highest level of TAC in the oldest workers is in parallel with the results of Limberaki.[12]. However, other studies have expressed the opposite such as Toczewska et al.[13] The TAC level became low in the oldest people. These variations are due to different causes, such as diet, stress, and sex, in addition to the differences in laboratory work.[14] In most cases, a serum TAC shows an increase with age. In some studies, increasing TAC was observed in patients suffering from cancer diseases.[15] Therefore, this increase may raise an alarm about the risk of cancer, taking into consideration that those old workers who spent a long period of their lives exposing to oil fume, for more than 20 years, could support this notion. This increase in TAC in oldest workers may be owing to increase in ROS due to a long period of exposure to oil products, which in turn leads to an increase in TAC as a part of a biological process to neutralize ROS and return to body hemostasis.

The decrease in TAC level in the oil group may be interpreted due to high ROS products owing to exposure to the oil fume. The TAC may be debilitated in scavenging this oxidative stress, leaving a low level of TAC in those workers. It has been noticed that workers, in general, do not take into consideration protective measures by wearing masks and gloves. In addition, the old oil machines and their maintenance on irregular bases may have a negative impact on the workers.

The oral hygiene of the workers in the oil refinery was generally bad. The PI of the study groups is significantly high. The first thing that has been noticed is the low educational level of the workers. The education level would impact oral hygiene.[16] Second, the stress that workers experience as well as long shift time leads to the loss of motivation and neglect of the oral hygiene. Consequently, there is a significant increase in GI in the study groups.

Interestingly, the oral ulceration, in addition to white and red patches have not been seen among refinery workers despite the exposure to oil fumes and pollution. This may be attributed to the increased level of serum immunoglobulin A in saliva. Therefore, the mucosal immunity has increased in response to the exposure to pollution and oil fumes.[17]

To conclude, the oral lesions were absent in oil workers. The lower TAC levels in the study groups may represent the effects of exposure to the oil fume in the oil refinery. The significant low TAC level in the oil group at the same time with increased CAL may reflect the impact of oil on the periodontal condition. This finding showed that the research has met the hypothesis that exposure to oil fume could decrease the TAC and exacerbate periodontal disease but not enhance oral lesions due to increased mucosal immunity in response to oil fume.[18]. However, there was no strong correlation between TAC and periodontal indices, which can be attributed to low sample numbers. TAC may be considered as an indicator to track the severity of the periodontal disease. The study has some limitations as it is a pilot study with a small sample size, so the generalization of our results is not going to be valid. Further study and a larger number of participants may be needed to shed light on these important findings in the diagnosis of oral and periodontal disease.


We wish to thank Dr Aseel Alani for her communication assistance and collaboration and Dr. Ali Hassan Hayyawi for his kind support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Uzma N, Kumar SS, Hazari MAH. Exposure to benzene induces oxidative stress, alters the immune response and expression of p53 in gasoline filling workers. Am J Ind Med 2010;53:1264–70.  Back to cited text no. 4
Chapple IL, Mason GI, Garner I et al.Enhanced chemiluminescent assay for measuring the total antioxidant capacity of serum, saliva and crevicular fluid. Ann Clin Biochem 1997;34:412–21.  Back to cited text no. 5
Ramfjord SP. The Periodontal Disease Index (PDI). J Periodontol 1967;38:602–10.  Back to cited text no. 6
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Loe H. The Gingival Index, the Plaque Index and the Retention Index Systems. J Periodontol,1967;38 Suppl:610–6.  Back to cited text no. 8
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Ryder MI. Comparison of neutrophil functions in aggressive and chronic periodontitis. Periodontol 2000. 2010;53:124–37.  Back to cited text no. 10
Scott DA, Krauss JL. Neutrophils in periodontal inflammation. Front Oral Biol 2012;15:56–83.  Back to cited text no. 11
Limberaki E, Eleftheriou P, Vagdatli E, Kostoglou V, Petrou Ch. Serum antioxidant status among young, middle-aged and elderly people before and after antioxidant rich diet. Hippokratia 2012;16:118–23.  Back to cited text no. 12
Toczewska J, Maciejczyk M, Konopka T, Zalewska A. Total oxidant and antioxidant capacity of gingival crevicular fluid and saliva in patients with periodontitis: review and clinical study. Antioxidants 2020;9:1–16.  Back to cited text no. 13
Zenthöfer A, Meyer-Kühling I, Hufeland A et al.Carers’ education improves oral health of older people suffering from dementia- results of an intervention study. Clin Interv Aging 2016;11:1755–62.  Back to cited text no. 14
Huang HY, Appel LJ. Supplementation of diets with -tocopherol reduces serum concentrations of γ and δ-tocopherol in humans. J. of Nutrition 2003;133:3137–40.  Back to cited text no. 15
Stein C, Santos NML, Hilgert JB, Hugo FN. Effectiveness of oral health education on oral hygiene and dental caries in schoolchildren: systematic review and meta-analysis. Community Dent Oral Epidemiol 2018:46:30–7.  Back to cited text no. 16
Martin S, Michael G. Burkett’s Oral Medicine Diagnosis and Treatment. 10th ed. Hamilton Ontario: BC Decker Inc; 2003:p. 610.  Back to cited text no. 17
Hamza AS, Ahmed JN. Assessment of the oral findings, salivary oxidative status and IgA level among group of workers exposed to petroleum pollutants in Al-Daura oil refinery. J Baghdad Coll Dent 2015;27:48–53.  Back to cited text no. 18
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Figure 3. figshare. Figure.2022.  Back to cited text no. 19
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Figure 4. figshare. Figure. 2022.  Back to cited text no. 20
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Figure 5. figshare. Figure. 2022.  Back to cited text no. 21
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Figure 6. figshare. 2022. Figure.  Back to cited text no. 22
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Table 1. figshare. 2022. Figure.  Back to cited text no. 23
Al-Qarakhli AMA, Mudher SH, Ali SM, Majid AY. Table 2. figshare. Figure. 2022.  Back to cited text no. 24


  [Figure 1], [Figure 2]


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