Quantification of DNA Double Strand Breaks and Oxidation Response in Children and Adults Undergoing Dental CBCT Scan

Abstract

Assessing the possible biological effects of exposure to low doses of ionizing radiation (IR) is one of the prime challenges in radiation protection, especially in medical imaging. Today, radiobiological data on cone beam CT (CBCT) related biological effects are scarce. In children and adults, the induction of DNA double strand breaks (DSBs) in buccal mucosa cells and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and antioxidant capacity in saliva samples after CBCT examination were examined. No DNA DSBs induction was observed in children nor adults. In children only, an increase in 8-oxo-dG levels was observed 30 minutes after CBCT. At the same time an increase in antioxidant capacity was observed in children, whereas a decrease was observed in adults. Our data indicate that children and adults react differently to IR doses associated with CBCT. Fully understanding these differences could lead to an optimal use of CBCT in different age categories as well as improved radiation protection guidelines.

Figure 1

No DNA double strand breaks (DSBs) are induced in buccal mucosal cells (BMCs) after cone beam computed tomography (CBCT) examination, neither in children nor in adults. No significant increases in the amount of γH2AX/53BP1 co-localized foci were observed 30 minutes and 24 hours after CBCT examination in children (Black dots; N = 38, degrees of freedom = 2, Friedman statistic = 2.7, p = 0.2538) and in adults (Red dots; N = 13, degrees of freedom = 2, Friedman statistic = 1.0, p = 0.6065). Before (Mann-Whitney U value = 121, p = 0.0020), 30 minutes after (Mann-Whitney U value = 145, p = 0.0146) and 24 hours after CBCT (Mann-Whitney U value = 170, p = 0.0487) the amount of DSBs was significantly higher in children then in adults. Only the data from patients of which results were obtained for all time points were included. Green dotted line = average number of foci; *p ≤ 0.05; **p ≤ 0.0021.

Figure 2

Excretion of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) into saliva is increased after cone beam computed tomography (CBCT) examination in children but not in adults. Only data from patients of which results were obtained for both time points were included. In children there is a significant average increase of 121% in 8-oxo-dG excretion 30 minutes after CBCT examination (N = 68, DF = 67, t value = 4, p < 0.0001). In adults there is an average increase in 8-oxo-dG excretion of 59% (N = 19, DF = 18, t value = 1.58, p = 0.1317). Green dotted line = average; ***p < 0.0001.

Figure 3

No dose response in 8-oxo-dG excretion in saliva 30 minutes after cone beam computed tomography in children. No visible dose response (linear or otherwise) was observed in 8-oxo-dG excretion in children. Radiation doses were the absorbed doses at the salivary glands as calculated by MC simulations^,. Black full line: dose response curve; black dotted curved lines: 95% confidence interval of the dose response curve.

Figure 4

Ferric reducing antioxidant power (FRAP) values increase in saliva samples from children after cone beam computed tomography (CBCT) examination, while decreasing in saliva samples from adults. In children (black violin plots) a significant increase in FRAP values was observed 30 minutes after CBCT examination (N = 117, t-value = 1.98, degrees of freedom (DF) = 116, p = 0.0498). In adults (red violin plots) a significant decrease was observed 30 minutes after CBCT examination (N = 17, t-value = 2.22, DF = 16, p = 0.0412). The FRAP values 30 minutes after CBCT are significantly higher in children than in adults (Welch-corrected t-value = 3.76, DF = 30.93, p = 0.0007). The response in children and adults differs significantly, with an average increase of 17.10 ± 8.62 in children and an average decrease of 17.40 ± 7.84 in adults (Welch-corrected t-value = 2.96, DF = 65, p = 0.0043). *p ≤ 0.05; ***p ≤ 0.0002.