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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 27  |  Issue : 1  |  Page : 25-28

Evaluation of genotoxic effect of X-rays on oral mucosa during panoramic radiography


Department of Oral Medicine and Radiology, Kanti Devi Dental College and Hospital, Mathura, Uttar Pradesh, India

Date of Submission29-Jul-2014
Date of Acceptance13-Jul-2015
Date of Web Publication12-Oct-2015

Correspondence Address:
Mahima Sandhu
House No. 347, Industrial Area Phase-IX, Mohali - 160 062, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.167070

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   Abstract 

Introduction: X-rays are potent mutagenic agents capable of inducing both gene mutations and chromosomal aberrations. They act directly on the DNA molecule or indirectly through the formation of reactive compounds that interact with this molecule. In spite of their mutagenic potential, this kind of radiation is an important tool for diagnosis. Aim: The aim of this study is to analyze the genotoxic effects on oral mucosa during conventional and digital panoramic radiography. Objectives: 1. To assess the nuclear abnormalities, mainly micronuclei in exfoliated buccal mucosal cells, before X-ray exposure and 10 days after exposure using conventional and digital panoramic radiography. 2. Comparison of micronuclei count obtained during conventional and digital panoramic radiography. Materials and Methods: One hundred healthy individuals were chosen who were free of all deleterious habits. Epithelial buccal cells were obtained with an exfoliative cytobrush immediately before exposure and 10 days after exposure. The smears were stained using Giemsa stain and analyzed under low-power and high-power microscope. Results: There was a significant difference in the mean values obtained pre- and post-exposure to conventional panoramic radiography, as the mean value of micronuclei before exposure was 0.025 ± 0.01 which increased to 0.064 ± 0.02 post-exposure. Similarly, there was a significant difference in the mean values obtained pre- and post-exposure to digital panoramic radiography, as the mean value of micronuclei before exposure was 0.022 ± 0.01 which increased to 0.041 ± 0.01 post-exposure. In the present study, there was a highly significant increase in the number of micronuclei post-exposure in conventional panoramic radiography when compared to digital panoramic radiography. Conclusion: This results show that panoramic radiography does induce genotoxic effects in buccal epithelial cells and should be used only when indicated, and that digital panoramic radiography is safer as compared to conventional radiography.

Keywords: Buccal epithelial cells, genotoxic effects, genotoxicity, micronuclei, oral mucosa, panoramic radiography


How to cite this article:
Sandhu M, Mohan V, Kumar JS. Evaluation of genotoxic effect of X-rays on oral mucosa during panoramic radiography. J Indian Acad Oral Med Radiol 2015;27:25-8

How to cite this URL:
Sandhu M, Mohan V, Kumar JS. Evaluation of genotoxic effect of X-rays on oral mucosa during panoramic radiography. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Sep 21];27:25-8. Available from: http://www.jiaomr.in/text.asp?2015/27/1/25/167070


   Introduction Top


Ionizing radiations are potent mutagenic agents capable of inducing both mutation and chromosomal aberrations. For cancer prevention in workers chronically exposed to low-level ionizing radiation in nuclear power plants, occupational medicine essentially applies biomonitoring of exposure and effects. [1],[2],[3] To date, a variety of assays have been proposed in biomonitoring studies, including those that assess metaphase chromosomal aberrations, sister chromatid exchanges, DNA damage, and host cell reactivation. However, these methods are typically difficult and time consuming, or require highly qualified technicians to accurately read and interpret slides. For these reasons, simple tests like the micronucleus test applied to uncultured exfoliated cells have been encouraged. [3] Accumulating evidence suggests that radiographs, which are widely used for diagnosis in medical and dental practices, can induce cytotoxic effects and cause DNA damage. Furthermore, the nucleus (including its genetic material) is more radiosensitive than the cytoplasmic structures of cell. [4],[5],[6],[7],[8],[9],[10] The present study was undertaken to study and compare the genotoxic effects caused by conventional and digital panoramic radiography. From this study, an attempt has been made to know the amount of risk involved due to radiation exposure in panoramic radiography.


   Materials and Methods Top


The present study was conducted in the Department of Oral Medicine and Radiology of Kanti Devi Dental College and Hospital, Mathura. The study group comprised 100 subjects who were randomly selected and divided into two groups. Ethical clearance was obtained from the institutional ethical committee of the college. Group I consisted of 50 females who were free from any oral mucosal lesion and not having any adverse habit; they were subjected to conventional panoramic radiography. Group II consisted of 50 females who were free from any oral mucosal lesion and not having any adverse habit; they were subjected to digital panoramic radiography. Individuals with adverse habits, those who had undergone any kind of radiograph in the past 6 months, and those with history of any disease or using any medication during the past 6 months were excluded from the study. Subjects were asked to rinse their mouth thoroughly with water. Exfoliated buccal cells were obtained by rolling the cytobrush against the buccal mucosa for 1 min. The cells were smeared over a precleaned, coded microscopic slide and immediately fixed with fixative containing 80% alcohol. The frequency of MN in BEC was evaluated by scoring 1000 cells on each slide. Scoring was done by a senior pathologist, according to the criteria established by Tolbert. [11],[12] After taking cytosmear, the individual was subjected to panoramic radiography and after 10 days, again a cytosmear was made from the same individual and subjected to the micronuclei evaluation.

Statistical analysis

Micronuclei count both during pre-exposure and 10 days after exposure was found in percentage. Data were analyzed using SPSS 16.0 for Windows and comparison of the mean values of all the study groups was carried out using unpaired Student's t-test. The difference of the mean values of the two observers was calculated using paired Student's t-test.


   Results Top


The mean value of micronuclei was found to be 0.025 ± 0.01 pre-exposure and 0.064 ± 0.02 post-exposure to conventional panoramic radiography. The difference between the mean values obtained was statistically significant as it shows more micronuclei post-exposure (P < 0.00). The mean value of micronuclei was found to be 0.022 ± 0.01 pre-exposure and 0.041 ± 0.01 post-exposure to digital panoramic radiography. The difference between the mean values obtained was statistically significant as it shows more micronuclei post-exposure (P < 0.00). The mean value of micronuclei was found to be 0.064 ± 0.02 in conventional panoramic radiography post-exposure. The mean value of micronuclei was found to be 0.041 ± 0.01 in digital panoramic radiography post-exposure. The difference between the mean values obtained was statistically significant as it showed more micronuclei post-exposure after conventional panoramic radiography (P < 0.00) [Table 1] and [Graph 1 [Additional file 1] ].
Table 1: Comparison of micronuclei observed per 1000 cells post-exposure between conventional and digital panoramic radiography

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   Discussion Top


Micronucleus is a small additional nucleus and is readily identifiable by light microscopy. During the last few decades, it has generally been used as a biomarker of chromosomal damage, genome instability, and cancer risk. Therefore, micronuclei scoring can be used as a biomarker to identify different pre-neoplastic conditions much earlier than the manifestations of clinical features. The results of our study suggest that panoramic radiography does induce genotoxicity in buccal epithelial cells. In the present study, the mean value of micronuclei per 1000 cells increased from 0.025 to 0.064 after exposure, suggesting increased genotoxicity after conventional panoramic radiography (P < 0.00). In the present study, the mean value of micronuclei per 1000 cells increased from 0.022 to 0.041 ten days after digital panoramic radiography exposure, suggesting highly significant increase in genotoxicity after the exposure (P < 0.00).

Our study is in accordance with the study results of Cerqueria et al. [6] which showed significantly increased micronucleus frequency post-exposure. In the study by Pai et al., [3] the mean value of micronuclei increased from 0.0046% to 0.0062% after exposure. In the study done by Sheikh et al., [10] the total number of micronuclei in epithelial buccal cells before panoramic exposure was 140, which increased to 149 after exposure. The mean micronuclei count increased from 1.75 ± 1.26 to 1.86 ± 1.07 after exposure. In the study performed by Angelieri et al., [7] the mean frequency of micronucleated cells was 0.02%. There was no statistically significant difference after X-ray exposure. Recent studies evaluating the genotoxic effects of panoramic dental radiography on exfoliated cells from buccal mucosa pre- and post-exposure are presented in [Table 2]. Our study is in accordance with the previous literature which illustrates that conventional methods of radiography cause more genotoxic changes as compared to digital radiography. Pai et al. [3] reported that the decrease in number of micronuclei count was due to decrease in effective dose (5-14 μSv) of digital panoramic radiography, which is in accordance with the findings of Cerqueria et al. [6] and Angelieri et al., when compared to the effective dose of conventional panoramic radiography (21.4 μSv).
Table 2: Recent studies of the association between micronuclei and panoramic radiography

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It is important to be attentive to the fact that genotoxic response to mutagenic agent exposure depends on individual genetic variability and other constitutional factors such as age and gender. The population characteristics and methodological aspects like differences in sites, collection of cells, fixing techniques, various staining procedures, number of cells counted, scoring criteria for micronuclei, etc. may affect the results.


   Conclusion Top


Radiation exposure from panoramic radiography does induce statistically significant increase in micronuclei. The frequency of buccal cell micronuclei was found to increase following panoramic radiography compared with the frequency prior to radiological exposure, suggesting genotoxic effects in buccal epithelial cells.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Angelieri F, de Cássia Gonçalves Moleirinho T, Carlin V, Oshima CT, Ribeiro DA. Biomonitoring of oral epithelial cells in smokers and non-smokers submitted to panoramic X-ray: Comparison between buccal mucosa and lateral border of the tongue. Clin Oral Investig 2010;14:669-74.  Back to cited text no. 1
    
2.
Angelieri F, de Oliveira GR, Sannomiya EK, Ribeiro DA. DNA damage and cellular death in oral mucosa cells of children who have undergone panoramic dental radiography. Pediatr Radiol 2007;37:561-5.  Back to cited text no. 2
    
3.
Pai A, Sharma RC, Nail RM, Guruprasad Y. Biomonitoring of genotoxic effect of gingival epithelial cells exposed to digital panoramic radiography. J Orofac Sci 2012;4:124-8.  Back to cited text no. 3
  Medknow Journal  
4.
Cerqueria EM, Gomes-Filho IS, Trinade S, Lopes MA, Passos JS, Machado-Santelli GM, Genetic damage in exfoliated cells from oral mucosa of individuals exposed to X-rays during panoramic dental radiographies. Mutat Res 2004;562:111-7.  Back to cited text no. 4
    
5.
Cerqueira EM, Meireles JR, Lopes MA, Junqueira VC, Gomes-Filho IS, Trindade S, et al. Genotoxic effects of X-rays on keratinized mucosa cells during panoramic dental radiography. Dentomaxillofac Radiol 2008;37:398-403.  Back to cited text no. 5
    
6.
da Silva AE, Rados PV, da silva Lauxen I, Gedoz L, Villarinho EA, Fontanella V. Nuclear changes in tongue epithelial cells following panoramic radiography. Mutat Res 2007;632:121-5.  Back to cited text no. 6
    
7.
Angelieri F, Carlin V, Saez DM, Pozzi R, Ribeiro DA. Mutagenicity and cytotoxicity assessment in patients undergoing orthodontic radiographs. Dentomaxillofac Radiol 2010;39:437-40.  Back to cited text no. 7
    
8.
Waingade M, Medikeri RS. Analysis of micronuclei in buccal epithelial cells in patients subjected to panoramic radiography. Indian J Dent Res 2012;23:574-8.  Back to cited text no. 8
[PUBMED]  Medknow Journal  
9.
Popova L, Hishkilova D, Hadjidekova VB, Hristova RP, Atanasova P, Hadjidekova VV, et al. Micronucleus test in buccal epithelium cells from patients subjected to panoramic radiography. Dentomaxillofac Radiol 2007;36:168-71.  Back to cited text no. 9
    
10.
Sheikh S, Pallagatti S, Grewal H, Kalucha A, Kaur H. Genotoxicity of digital panoramic radiography on oral epithelial tissues. Quintessence Int 2012;43:719-25.  Back to cited text no. 10
    
11.
Samanta S, Dey P. Micronucleus and its applications. Diagn Cytopathol 2010;40:84-90.  Back to cited text no. 11
    
12.
Tolbert PE, Shy CM, Allen JW. Micronuclei and other nuclear anomalies in buccal smears: A field test in snuff users. Am J Epidemiol 1991;134:840-50.  Back to cited text no. 12
    



 
 
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  [Table 1], [Table 2]



 

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