Mutagenicity and cytotoxicity in patients submitted to ionizing radiation

Abstract

Objectives: To evaluate and compare mutagenicity (micronucleus) and cytotoxicity (karyorrhexis, pyknosis, and karyolysis) in exfoliated buccal mucosa cells of children following cone beam computed tomography (CBCT) or conventional radiograph exposure necessary for orthodontic planning. Materials and Methods: A total of 49 healthy children were submitted to CBCT or a conventional orthodontic radiographic protocol; they were divided into two groups based on exam: CBCT (n 5 24) and Radiographic Set (n 5 25) groups. The micronucleus test in the exfoliated buccal mucosa cells was applied.Results: There was not a statistically significant difference (P . .05) found between the number of micronucleated buccal mucosa cells (MNC) before and after exposure to radiation in either group, showing that neither group experienced a mutagenic effect. However, radiation did cause other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis, and karyolysis, in both groups (P , .05). The CBCT group presented a greater increase in cell death than was noted in the Radiographic Set group (P , .044). Conclusion: According to the micronucleus test, mutagenicity was not induced by the CBCT or the conventional radiographs, but cytotoxicity was verified after these exams, especially after CBCT. That might have happened once the CBCT group received a greater radiation dose than the Radiographic Set group as a result of the protocols used in orthodontic planning for this study. (Angle Orthod. 2013;83:104-109.)

Could formaldehyde induce mutagenic and cytotoxic effects in buccal epithelial cells during anatomy classes?

“…Results are expressed in percentages (%). Similar analyses were established in previous published studies (13,18). The processing procedures and analysis were performed at the LUCCAR Lab, Histology Sector, Morphology Department, Federal University of Espírito Santo, Vitória, Brazil.…”

“…These facts highlight one advantage of the MN assay, an in vivo exam that elucidates the effects of toxic agents directly on a target tissue, the buccal epithelium. The limited cost, ease of counting, person-time required and precision obtained from scoring large numbers of cells improve the popularity of this non-invasive method (13). …”

“…MN evaluations are made in buccal epithelial exfoliated cells (BEC) as well, and this test is considered to be the least invasive method available to measure DNA damage in humans (9). Due to its ability to assess the activity of many chemical or physical carcinogenic and mutagenic agents in situ, the MN test in the BEC is the choice of many recent human biomonitoring studies: alcohol (10), tobacco (11), mouthrinses (12) and radiographs (13). …”

Highlights on orthodontics literature

“…To elucidate these questions, Brazilian researchers proposed to evaluate the behavior of oral cavity cells submitted to protocols of conventional and tomographic orthodontic documentation. 2 The results found (Fig 1) demonstrated cytotoxicity in cells of the oral cavity submitted to conventional radiographs and cone beam computerized tomography. A larger number of cell deaths were found in the group in which computerized tomography was used.…”

Usefulness of Saliva Samples for Biomarker Studies in Radiation Research

“…24) as long as enough cells can be collected. In fact, a number of studies have investigated low-dose IR biomarkers in exfoliated buccal cells and reported a significant increase in micronucleus 10 days after exposure to panoramic radiography (25) or an increase in cytotoxicity after in vivo exposure to CT or radiography, with no difference in micronucleus frequency (26,27). Another study reported a doseresponse relationship in gH2AX induction after in vitro exposure of buccal cells up to 4 Gy (28).…”