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 = 24) and Radiographic Set (n = 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.

Figure 1.

Nuclear alterations evaluation following cone beam computed tomography (CBCT) or radiograph exposure (400× magnification, Feulgen/Fast Green stain): (a) micronucleated (arrow) and normal cells, (b) karyorrhexis (arrow), (c) karyolysis (arrow), and (d) pyknosis (arrow).