title: Low-dose dental irradiation decreases oxidative stress in osteoblastic MC3T3-E1 cells without any changes in cell viability, cellular proliferation and cellular apoptosis.
abstract: Cellular responses following low-dose irradiation have been widely debated. Several studies have revealed detrimental effects of low-dose irradiation; however, some studies have shown contrasting results. Moreover, the effects of periapical irradiation on osteoblastic cells have not yet been revealed. Therefore, in this study, we tested the hypothesis that low-dose dental irradiation of osteoblastic cells reduces reactive oxygen species (ROS) production and leads to increased cellular proliferation and high-dose dental irradiation of osteoblastic cells increases ROS production and leads to cellular apoptosis.
  
  
  METHODS
  We irradiated MC3T3-E1 cells with various doses of periapical irradiation (0, 1, 2, 5 and 10 doses, 1.5 mGy/dose). We evaluated cell viability using MTT assay, the expression of Bax and Bcl-2, as markers for apoptosis and the expression of cyclin D1 as a marker for cell proliferation 24h after each irradiation. We also measured ROS production 4h following each irradiation.
  
  
  RESULTS
  ROS production was significantly reduced after one dose of periapical irradiation (1.5 mGy); however, after 10 doses (15 mGy), ROS production was significantly increased (p<0.05). None of the doses of dental radiation affected cell viability as determined by MTT assay, nor did they change the apoptotic marker: (the Bax/Bcl-2 ratio). However, 10 doses of dental irradiation significantly decreased the expression of cyclin D1.
  
  
  CONCLUSIONS
  Our findings suggest that low-dose dental radiation may help to detoxify osteoblastic cells by reducing ROS production without any changes in cell viability, cellular apoptosis or proliferation. However, high-dose dental radiation impairs osteoblastic proliferation via increase ROS production without any changes in cell viability or apoptotic responses.
authors.affiliation: Department of Oral Biology and Diagnostic Science, Faculty of Dentistry, Chiang Mai University, Thailand.
authors.forename: Sakarat N
authors.initials: SN
authors.lastname: Pramojanee
authors.forename: Wasana
authors.initials: W
authors.lastname: Pratchayasakul
authors.forename: Nipon
authors.initials: N
authors.lastname: Chattipakorn
authors.forename: Siriporn C
authors.initials: SC
authors.lastname: Chattipakorn
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000000981:diagnostic imaging*; D011861:Radiography, Dental / Q000009:adverse effects / Q000379:methods; D017382:Reactive Oxygen Species / Q000032:analysis* / Q000528:radiation effects
chemical_list: D017382:Reactive Oxygen Species