Genetic damage in exfoliated cells from oral mucosa of individuals exposed to X-rays during panoramic dental radiographies.

The genotoxic effects of X-ray emitted during dental panoramic radiography were evaluated in exfoliated cells from oral epithelium through a differentiated protocol of the micronucleus test. Thirty-one healthy individuals agreed to participate in this study and were submitted to this procedure for diagnosis purpose after being requested by the dentist. All of them answered a questionnaire before the examination. Cells were obtained from both sides of the cheek by gentle scrapping with a cervical brush, immediately before the exposure and after 10 days. Cytological preparations were stained according to Feulgen-Rossenbeck reaction and analyzed under light and laser scanning confocal microscopies. Micronuclei, nuclear projections (buds and broken eggs) and degenerative nuclear alterations (condensed chromatin, karyolysis and karyorrhexis) were scored. The frequencies of micronuclei, karyolysis and pycnosis were similar before and after exposure (P > 0.90), whereas the condensation of the chromatin and the karyorrhexis increased significantly after exposure (P < 0.0001). In contrast, both bud and broken egg frequencies were significantly higher before the examination (P < 0.005), suggesting that these structures are associated to the normal epithelium differentiation. The results suggest that the X-ray exposure during panoramic dental radiography induces a cytotoxic effect by increasing apoptosis. We also believe that the score of other nuclear alterations in addition to the micronucleus improves the sensitivity of genotoxic effects detection.

[1]  M. P. Carty,et al.  Insights into UV-induced apoptosis: ultrastructure, trichrome stain and spectral imaging. , 2002, Micron.

[2]  P. Voisin,et al.  Is micronuclei yield variability a problem for overexposure dose assessment to ionizing radiation? , 1998, Mutation research.

[3]  F. Kassie,et al.  Use of the micronucleus assay with exfoliated epithelial cells as a biomarker for monitoring individuals at elevated risk of genetic damage and in chemoprevention trials. , 2001, Mutation research.

[4]  Martyn T. Smith,et al.  Use of the fluorescent micronucleus assay to detect the genotoxic effects of radiation and arsenic exposure in exfoliated human epithelial cells , 1996, Environmental and molecular mutagenesis.

[5]  M. Fenech.  The in vitro micronucleus technique. , 2000, Mutation research.

[6]  R. Feulgren,et al.  Mikroskopisch-chemischer Nachweis einer Nucleinsäure vom Typus der Thymonucleinsäure und die- darauf beruhende elektive Färbung von Zellkernen in mikroskopischen Präparaten. , 1924 .

[7]  S. B. Rao,et al.  Cytogenetic analysis of peripheral blood lymphocytes of occupational workers exposed to low levels of ionising radiation. , 1999, Mutation research.

[8]  P. Tolbert,et al.  Micronuclei and other nuclear anomalies in buccal smears: a field test in snuff users. , 1991, American journal of epidemiology.

[9]  S. C. Hall,et al.  Micronuclei in human lymphocytes as a biological dosemeter. Preliminary data following beta irradiation in vitro , 1988 .

[10]  M. Gonsebatt,et al.  Increased cytogenetic damage in outdoor painters. , 2000, Mutation research.

[11]  M. Fenech,et al.  The HUman MicroNucleus Project--An international collaborative study on the use of the micronucleus technique for measuring DNA damage in humans. , 1999, Mutation research.

[12]  R. Prathapan,et al.  Prediction of radiosensitivity of oral cancers by serial cytological assay of nuclear changes. , 1998, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[13]  G. Zúñiga-González,et al.  Evaluation of cisplatin + 5-FU, carboplatin + 5-FU, and ifosfamide + epirubicine regimens using the micronuclei test and nuclear abnormalities in the buccal mucosa. , 2003, Mutation research.

[14]  R. Marcos,et al.  Micronuclei in peripheral blood lymphocytes and buccal epithelial cells of Polish farmers exposed to pesticides. , 2001, Mutation research.

[15]  C. Paz-y-Miño,et al.  Telomeric associations in cigarette smokers exposed to low levels of X-rays. , 2001, Mutation research.

[16]  A. Johansson,et al.  Clonal chromosome aberrations and genomic instability in X-irradiated human T-lymphocyte cultures. , 1993, Mutation research.

[17]  R. Marcos,et al.  Cytogenetic biomonitoring of Spanish greenhouse workers exposed to pesticides: micronuclei analysis in peripheral blood lymphocytes and buccal epithelial cells. , 2000, Mutation research.

[18]  G. V. Vera,et al.  Assessment of genome damage in occupational exposure to ionising radiation and ultrasound. , 1997, Mutation research.

[19]  L. Révész,et al.  The frequency of micronuclei as a measure of cell survival in irradiated cell populations. , 1980, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[20]  W. L. Chen,et al.  Comparative evaluation of the in vitro micronucleus test and the comet assay for the detection of genotoxic effects of X-ray radiation. , 2000, Mutation research.

[21]  F. Sarto,et al.  Evaluation of chromosomal aberrations in lymphocytes and micronuclei in lymphocytes, oral mucosa and hair root cells of patients under antiblastic therapy. , 1990, Mutation research.

[22]  P. Tolbert,et al.  Micronuclei and other nuclear anomalies in buccal smears: methods development. , 1992, Mutation research.

[23]  D. Horvat,et al.  Chromosomal aberrations in persons occupationally exposed to annual x-irradiation doses lower than 25 mSv , 1992 .

[24]  Y. Odagiri,et al.  Influence of serum micronutrients on the incidence of kinetochore-positive or -negative micronuclei in human peripheral blood lymphocytes. , 1998, Mutation research.

[25]  K. Trott,et al.  Genomic instability in Chinese hamster cells after exposure to X rays or alpha particles of different mean linear energy transfer. , 1997, Radiation research.

[26]  R. Marcos,et al.  Low persistence of radiation-induced centromere positive and negative micronuclei in cultured human cells. , 1999, Mutation research.

[27]  J. G. Kalbfleisch.  Probability and Statistical Inference , 1977 .

[28]  V. Zhurkov,et al.  Cytogenetic investigation of women exposed to different levels of dioxins in Chapaevsk town. , 2001, Chemosphere.

[29]  G. Machado-Santelli,et al.  Biomonitoring of nurses handling antineoplastic drugs. , 1994, Mutation research.

[30]  H. Stich,et al.  Micronuclei in exfoliated human cells as a tool for studies in cancer risk and cancer intervention. , 1984, Cancer letters.

[31]  J. Śanchez-Corona,et al.  Determination of diesel genotoxicity in firebreathers by micronuclei and nuclear abnormalities in buccal mucosa. , 1998, Mutation research.