Evidence of genotoxicity and cytotoxicity of X-rays in the oral mucosa epithelium of adults subjected to cone beam CT

A systematic review and meta-analysis of the genotoxic and cytotoxic effects on oral epithelium induced by cone beam computed tomography

OBJECTIVE

To evaluate the occurrence of genotoxic and cytotoxic effects in oral epithelium after exposure of patients to cone beam computed tomography (CBCT).

METHODS

A systematic review (SR) was conducted following the PECO (Population, Exposure, Comparison, Outcome) criteria. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO). A search was performed on the PubMed, Scopus, ScienceDirect, and Google Scholar databases. Effect size and heterogeneity of data were evaluated statistically. The Joanna Briggs Institute questionnaire for observational studies was utilized to assess the risk of bias. The GRADE tool was applied for the assessment of the quality of evidence. Begg's funnel plot was used to evaluate publication bias.

RESULTS

In total, 10 full-text articles were included in the SR, with 6 of them in the meta-analysis. The SR showed a significant increase in micronuclei after exposure, with a large effect size of 1.03. For genotoxicity, the tau2 for heterogeneity was 0.96, the chi-squared test for heterogeneity P < .00001, the I2 statistics for random effects was 91%, and the overall effect for Z value was 2.46 (P = .01). The risk of bias was low, the quality of evidence was strong, and publication bias was absent.

CONCLUSION

CBCT can cause genotoxicity in the oral epithelium with a large effect size. The measure of cytotoxicity after CBCT exposure was not possible due to the lack of homogeneity of the included articles.

Associated risks with periodontal x-rays or CBCT scans: Are there any?

Periodontal and implant radiography, mainly including intra-oral peri-apical and cone beam computed tomography images, are crucial in the diagnosis and treatment planning process. However, radiation safety concerns have been a chronic concern over the years, leading to uncomfortable situations. It is therefore crucial to understand the actual radiation exposure to determine if the patients' fear of necessary diagnostic exams is justified. In this perspective article, we aimed to provide concise information on dental imaging exposure, risks, and benefits, comparing them to that of absorbed radiation from daily life activities; and secondarily, to help periodontists choose the best option for each case and become more confident in addressing patients' concerns and providing a summary of safety guidelines as a reference for them.

Comparative evaluation of mutagenic effects of two cone-beam computed tomography in oral mucosa cells

BACKGROUND

This pilot study aimed to evaluate the mutagenic effects in cells of the oral mucosa after exposure to two different cone beam computed tomography (CBCT).

METHODS

Eighteen adults were submitted to the different CBCT (Carestream CS8100 3D and I-CAT). The cells were collected immediately before the CBCT exposure and 10 days later, when the material was placed on a slide and stained using the Feulgen/Fast Green technique. Microscopic analysis counted micronuclei and other nuclear alterations, which are indicative of cytotoxicity such as pyknosis, karyolysis, karyorrhexis, and binucletion. 2000 cells were analyzed. The statistical analysis was performed with the Wilcoxon Signed-Rank test to compare the frequency of cellular alterations, and the Mann-Whitney U test to compare different CBCTs, both with a significance level of 5%.

RESULTS

There was no statistically significant difference in the micronucleated cell count before and after the exposition to the ionizing radiation from I-CAT (p = .298) and CS8100 3D (p = .203) A significate increase of pyknosis (p < .001), karyolysis (p < .001), karyorrhexis (p < .001), and binucletion (p < .001) were noted on I-CAT CBCT. There was no statistically significant difference in cellular alterations in CS8100 3D CBCT.

CONCLUSION

Despite the increase in micronuclei after exposure, this study indicates that there is no evidence of genotoxicity. On the other hand, the I-CAT CBCT produced cytotoxic effects.

Genotoxic and Cytotoxic Effects of Cone Beam Computed Tomography and Multidetector Computed Tomography on Exfoliated Buccal Epithelial Cells

Background

Cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) are frequently used in dental and maxillofacial problems. This study aimed to assess the genotoxicity and cytotoxicity effects of CBCT and MDCT radiographies on exfoliated buccal epithelial cells during dental examinations.

Methods

This prospective experimental study was conducted at Babol University of Medical Sciences (Babol, Iran) from March 2021 to April 2021. Buccal mucosa smears were collected bilaterally pre-exposure and 12 days after CBCT or MDCT examinations. To compare the frequency of micronuclei and other cytotoxic cellular changes such as pyknosis, karyolysis, and karyorrhexis, the paired sample t test and Wilcoxon test were used. In addition, independent sample t test, Mann-Whitney, and Chi square tests were used to investigate the differences between the imaging methods and between men and women. All statistical analyses were performed using the SPSS software, and P≤0.05 was considered statistically significant.

Results

The current study included 60 adult patients (30 patients in each group), ranging in age from 21 to 50 years. The micronuclei and the other cytotoxic cellular changes increased significantly after CBCT and MDCT radiographic examinations on the 12th day compared to the pre-exposure results (P<0.001). MDCT had statistically higher cytotoxic and genotoxic effects than CBCT (9.4%, 23.1%, and 40% higher values in micronucleus frequency, the mean frequency of micronuclei, and other cytotoxic changes, respectively). There were no significant differences between men and women in the two examination methods (P=0.46 and P=0.49, respectively).

Conclusion

Dental examinations with CBCT and MDCT can increase cytotoxicity and chromosomal damage in both men and women. Due to its lower radiation toxicities, CBCT can be recommended as an alternative to MDCT for dental examinations.

Does cone-beam computed tomography examination increase the micronuclei frequency in the oral mucosa exfoliated cells? A systematic review and meta-analysis

OBJECTIVE

This systematic review (SR) with meta-analysis aimed to evaluate the frequency of micronuclei in the oral mucosa exfoliated cells after cone-beam computed tomography (CBCT) examination.

METHODS

We performed language-independent computer-assisted data searches using PubMed databases, Cochrane, Embase, Web of Science all databases, and Google Scholar. The literature on micronucleus (MN) frequency of clinical trials before and after CBCT examination was included. The frequency of MN in exfoliated cells of the human oral mucosa was the primary outcome of the study. All statistical analyses were performed with R (version 4.1.0), RStudio (version 2022.02.2 + 485) software, and Meta packages (version 5.2-0). Two reviewers independently assessed the quality of the included studies by the EPHPP (Effective Public Health Practice Project) Modified scale with minor modifications. The heterogeneity of the data was analyzed using I² statistics, in which I² > 50% was considered substantial heterogeneity.

RESULTS

A total of 559 articles were selected through the search strategy. After screening titles and abstracts, nine full-text manuscripts were assessed for eligibility, and six observational studies were included in the meta-analysis. The present study showed a significant increase in MN frequency of human oral mucosal exfoliated cells 10 days after CBCT examination compared to baseline (SMD = - 0.56, 95%-CI = - 0.99 ~ - 0.13, p = 0.01). Because of the high heterogeneity among the studies (I² = 72%), after removing one study that was the main source of heterogeneity, excluding the study (I² = 47%), the common-effect model was chosen, and the meta-analysis also showed that the frequency of MN in human oral mucosa exfoliated cells increased significantly 10 days after CBCT examination (SMD =  - 0.35, 95%-CI =  - 0.59 ~  - 0.11, p = 0.004).

CONCLUSION

This review suggested that CBCT examination increases the frequency of micronuclei in oral mucosal exfoliated cells.

Genotoxicity and cytotoxicity effects of x-rays on the oral mucosa epithelium at different fields of view: A cone beam computed tomography technique

Background

Cone beam computed tomography (CBCT) is considered a common examination for dentistry problems. Cellular biology can be affected by exposure to ionizing radiations procedures. In this study, we aimed to assess the genotoxicity and cytotoxicity effects of CBCT dental examinations at two different fields of view (FOVs) in exfoliated buccal epithelial cells.

Methods

Sixty healthy adults participated in the current study. They were divided into two identical groups; CBCT with FOV of 6*6 cm2 and 8*11 cm2. Exfoliated oral mucosa cells were prepared immediately before and after 10-12 days of CBCT exposure. The cytological smears were stained with the Papanicolaou technique. The amounts of micronuclei and other cytotoxicity cellular changes (Pyknosis, Karyolysis, and Karyorrhexis) were evaluated. The variables of the parameters before and after CBCT examination in the two investigated FOVs were performed using Wilcoxon test and paired-samples t-test in SPSS software.

Results

The micronuclei and other cytotoxic changes parameters before and after CBCT exposure for both FOVs (6*6 and 8*11 cm2) increased significantly (p<0.001). Furthermore, a significant difference (p<0.05) was observed between the investigated parameters at the two FOVs. Notably, the FOV of 8*11 cm2 had more side effects than that of 6*6 cm2. There were no statistically significant among males and females for both FOVs.

Conclusion

CBCT examinations of dental disorders would increase the risks of inducing genetic damage. The cytotoxicity and chromosomal damage were considered in males and females in both investigated FOVs (6*6 and 8*11 cm2). In this regard, the use of CBCT must be following the ALARA principle.

Mutagenicity in oral cells of individuals exposed to radiofrequency generated by different smartphones

Aim: This study aimed to investigate whether non-ionizing radiation emitted by smartphones is likely to cause genotoxic effects on oral epithelial cells. Methods: Thirty adults were distributed into two groups according to the mobile phone brand used, namely Samsung (Samsung, Seoul, South Korea) and Apple (Apple, California, USA). The material was collected with gentle swabbing of the right and left buccal mucosa using a cervical brush, then the micronucleus test was performed. Results: The Mann-Whitney test with a 5% significance level did not reveal statistically significant differences in micronuclei frequency between the exposed and non-exposed sides (p=0.251). The different brands do not seem to cause risks of inducing genetic damage because there were no statistically significant differences between them (p=0.47). Conclusion: Therefore, our results suggest no correlations of micronuclei frequency in the exposed buccal cells of mobile phone users at the exposure standard levels observed.

Cytotoxicity, genotoxicity, and immunohistochemical expression of p53 in the oral mucosal epithelium of adults following cone-beam computed tomography

This study sought to assess the cytotoxicity, genotoxicity, and immunohistochemical (IHC) expression of p53 in the oral mucosal epithelium of adults following cone-beam computed tomography (CBCT). This before-and-after observational study evaluated 30 patients (15 males and 15 females); mean age 35 years, who required CBCT. Exfoliating epithelial cells of the buccal mucosa were collected with a cotton swab immediately before and 10 days after CBCT. Following Papanicolaou staining, genotoxicity was evaluated by the micronucleus assay. The frequencies of pyknosis, karyorrhexis, karyolysis, budding and binucleation as cytotoxicity factors were also recorded. Expression of p53 was evaluated by IHC staining. Data were analyzed by paired samples t-test. Micronucleated cells, pyknosis, karyorrhexis, karyolysis, budding, cytotoxicity, and expression of p53 increased significantly after CBCT. CBCT exerts genotoxic and cytotoxic effects and leads to overexpression of p53 protein in the oral buccal mucosal cells.

Can exposure to panoramic radiographs induce genotoxic effects on the oral epithelium? A systematic review with meta-analysis

OBJECTIVE

To evaluate, through a systematic review (SR) with meta-analysis, the occurrence of genotoxic effects in the oral epithelium after the exposure of patients to panoramic radiographs.

METHODS

An SR was performed with the PICOS (Population, Intervention, Comparison, Outcome, and Study design) strategy, aiming to answer the following question: "Can panoramic radiographs induce genotoxic effects on the oral epithelium?" The study was registered in the PROSPERO (International prospective register of systematic reviews) platform. A systematic search was performed in the following electronic databases: PubMed (including MedLine), Scopus, Embase, LILACS, Medline EbscoHost, and Google Scholar. Treatment effects were defined as standardized mean difference (SMD), and 95% confidence intervals (CI) were established. The Joanna Briggs Institute questionnaire for observational studies was applied to assess the risk of bias. The GRADE tool was used to assess the quality of evidence of the SR.

RESULTS

A total of 251 potentially relevant studies were selected through the search strategy. After screening titles and abstracts, 11 full-text manuscripts were assessed for eligibility and nine observational studies were included in the meta-analysis. The present study showed an increase in micronuclei after the exposure (SMD = 0.21, 95% CI, 0.03 to 0.28, p = 0.02), with a Tau²index = 0.00, Chi² = 2.35, and p-value = 0.97. Therefore, the articles selected were considered homogeneous and the I² of 0% indicated low heterogeneity.

CONCLUSION

According to the studies analysed, although the quality of evidence was considered low, panoramic radiographs can cause genotoxic damage in the oral epithelium but with a small effect size.

Genotoxicity and cytotoxicity of cone beam computed tomography in children

BACKGROUND

Dental radiographs are essential tools for diagnosis. However, there are significant concerns about the dangerous effect of radiation especially on children. The aim of this study was to evaluate genotoxicity and cytotoxicity in the exfoliated cells of buccal mucosa of children subjected to Cone Beam Computed Tomography (CBCT).

METHODS

The study included 18 healthy children aged (9-12 years) who were exposed to CBCT. All CBCT scans were performed with the i-CAT CBCT. Exfoliated buccal cells were scraped from the left and right cheek immediately before the exposure, after 10 ± 2 days, and after 1 month. Cells were stained using Feulgen/fast green stain and examined under light microscopy. Genotoxicity (Micronuclei) and cytotoxicity (condensed chromatin, karyorrhexis, pyknosis, and karyolysis) were scored. Statistical analysis was performed using the McNemar test, Wilcoxon Signed-Rank test, and Mann-Whitney U test at a significance level of p < 0.05.

RESULTS

There were statistically significant differences in the mean percentages of micronuclei, condensed chromatin, karyorrhexis, pyknosis, and karyolysis before and 10 ± 2 days after the CBCT scan (p < 0.05). There were no statistically significant differences in the frequency of micronuclei, condensed chromatin, karyorrhexis, or pyknosis before and 1 month after the exposure (p > 0.05) except for karyolysis (p < 0.05).

CONCLUSIONS

CBCT may induce genotoxicity and cytotoxicity in buccal mucosa cells of children. Therefore, CBCT should not be prescribed unless necessary as it cannot be considered a risk-free procedure.

Radiobiological risks following dentomaxillofacial imaging: should we be concerned?

OBJECTIVES

This review aimed to present studies that prospectively investigated biological effects in patients following diagnostic dentomaxillofacial radiology (DMFR).

METHODS

Literature was systematically searched to retrieve all studies assessing radiobiological effects of using X-ray imaging in the dentomaxillofacial area, with reference to radiobiological outcomes for other imaging modalities and fields.

RESULTS

There is a lot of variability in the reported radiobiological assessment methods and radiation dose measures, making comparisons of radiobiological studies challenging. Most radiological DMFR studies are focusing on genotoxicity and cytotoxicity, data for 2D dentomaxillofacial radiographs, albeit with some methodological weakness biasing the results. For CBCT, available evidence is limited and few studies include comparative data on both adults and children.

CONCLUSIONS

In the future, one will have to strive towards patient-specific measures by considering age, gender and other individual radiation sensitivity-related factors. Ultimately, future radioprotection strategies should build further on the concept of personalized medicine, with patient-specific optimization of the imaging protocol, based on radiobiological variables.

Gene expression changes and DNA damage after ex vivo exposure of peripheral blood cells to various CT photon spectra

Dual-energy CT provides enhanced diagnostic power with similar or even reduced radiation dose as compared to single-energy CT. Its principle is based on the distinct physical properties of low and high energetic photons, which, however, may also affect the biological effectiveness and hence the extent of CT-induced cellular damage. Therefore, a comparative analysis of biological effectiveness of dual- and single-energy CT scans with focus on early gene regulation and frequency of radiation-induced DNA double strand breaks (DSBs) was performed. Blood samples from three healthy individuals were irradiated ex vivo with single-energy (80 kV and 150 kV) and dual-energy tube voltages (80 kV/Sn150kV) employing a modern dual source CT scanner resulting in Volume Computed Tomography Dose Index (CTDIvol) of 15.79-18.26 mGy and dose length product (DLP) of 606.7-613.8 mGy*cm. Non-irradiated samples served as a control. Differential gene expression in peripheral blood mononuclear cells was analyzed 6 h after irradiation using whole transcriptome sequencing. DSB frequency was studied by 53BP1 + γH2AX co-immunostaining and microscopic evaluation of their focal accumulation at DSBs. Neither the analysis of gene expression nor DSB frequency provided any evidence for significantly increased biological effectiveness of dual-energy CT in comparison to samples irradiated with particular single-energy CT spectra. Relative to control, irradiated samples were characterized by a significantly higher rate of DSBs (p < 0.001) and the shared upregulation of five genes, AEN, BAX, DDB2, FDXR and EDA2R, which have already been suggested as radiation-induced biomarkers in previous studies. Despite steadily decreasing doses, CT diagnostics remain a genotoxic stressor with impact on gene regulation and DNA integrity. However, no evidence was found that varying X-ray spectra of CT impact the extent of cellular damage.

Method validation to assess in vivo cellular and subcellular changes in buccal mucosa cells and saliva following CBCT examinations

OBJECTIVES

Cone-beam CT (CBCT) is a medical imaging technique used in dental medicine. However, there are no conclusive data available indicating that exposure to X-ray doses used by CBCT are harmless. We aim, for the first time, to characterize the potential age-dependent cellular and subcellular effects related to exposure to CBCT imaging. Current objective is to describe and validate the protocol for characterization of cellular and subcellular changes after diagnostic CBCT.

METHODS

Development and validation of a dedicated two-part protocol: 1) assessing DNA double strand breaks (DSBs) in buccal mucosal (BM) cells and 2) oxidative stress measurements in saliva samples. BM cells and saliva samples are collected prior to and 0.5 h after CBCT examination. BM cells are also collected 24 h after CBCT examination. DNA DSBs are monitored in BM cells via immunocytochemical staining for γH2AX and 53BP1. 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and total antioxidant capacity are measured in saliva to assess oxidative damage.

RESULTS

Validation experiments show that sufficient BM cells are collected (97.1 ± 1.4 %) and that γH2AX/53BP1 foci can be detected before and after CBCT examination. Collection and analysis of saliva samples, either sham exposed or exposed to IR, show that changes in 8-oxo-dG and total antioxidant capacity can be detected in saliva samples after CBCT examination.

CONCLUSION

The DIMITRA Research Group presents a two-part protocol to analyze potential age-related biological differences following CBCT examinations. This protocol was validated for collecting BM cells and saliva and for analyzing these samples for DNA DSBs and oxidative stress markers, respectively.