Cytogenetic biomonitoring of Brazilian dentists occupationally exposed to low doses of X-radiation

Multicentric evaluation of conventional dosimetry vs bio-dosimetry over a period of two years for a three-point contact

Background

Dental radiology represents the best model for evaluating the effects of low-dose ionizing radiation. Therefore, this study evaluated the awareness on radiation hygiene among dental ancillary personnel through a questionnaire and their absorbed doses by physical and biologic dosimetry.

Methods

The multicentric study included two groups. Group I (N = 30) consisted of dental staff involved in dental radiology. An equal number of personnel who were not related to radiology formed the control group. Knowledge (K), attitude (A), and practice (P) of participants were assessed using a KAP questionnaire. Radiation exposure was evaluated by physical dosimetry at 3 time periods: at the beginning of the study (T1), after 10 months (T2), and at the end after 20 months (T3). Similarly, biologic dosimetry was also carried out at 3 time points by dicentric chromosome aberration assay. The data were compared using percentage analysis, analysis of variance (one-way analysis of variance), and Student's t- test.

Results

The KAP survey demonstrated enhanced understanding of radiation protection measures and its sound practice by the participants. Physical dosimetry showed a significant increase in absorbed dose at 3 time points: T1, T2, and T3. However, no chromosomal aberrations were observed in blood lymphocytes for any of the participants in the optimized 4-day biodosimetry protocol.

Conclusion

Good radiation protection protocols-safe distance from the radiation source and wear of lead aprons and thyroid collars-ensured low absorbed doses. The 4-day protocol is an important step toward developing biodosimetry laboratories in the Armed Forces Medical Services for clinical and national radiation countermeasure strategies.

Brazilian workers occupationally exposed to different toxic agents: A systematic review on DNA damage

The evaluation of genotoxicity in workers exposed to different toxic agents is very important, especially considering the association between these exposures in a chronic context and DNA damage. Assessing biomarkers of exposure and, when possible, early biomarkers of effect, contributes to elucidating the potential toxic mechanisms involved in genotoxicity and its contribution to chronic non-communicable diseases. In Brazil, the biggest country in South America, workers are exposed to hazardous physical and chemical agents. Considering that these exposures occur, in most cases, throughout the worker's whole life, this is an important public health concern in Brazil. Therefore, this systematic review aims to analyze occupational exposure to chemical and physical agents and the association with DNA damage in studies carried out in Brazil from 1980 to 2021. A systematic and comprehensive literature search was performed in different databases based on occupational exposure to chemical and physical agents and DNA damage. Only full articles on studies that investigated experimental evidence on occupational exposure in Brazil and assessed DNA damage were included, amounting to 89 articles. Five main occupational exposure groups were identified: pesticides (36%), organic solvents (20%), dust and particles (16%), metals (11%), and ionizing radiation (6%). Another group called "others" included studies (11%) that did not fall into these main groups. It was found that comet assay and micronucleus tests are the most adopted methods to detect DNA damage. Occupational exposures were most associated with DNA damage. However, further improvements in study design would be needed to better characterize the association between biomonitoring and DNA damage, particularly to account for confounding factors.

Exposure to Radiation During Work Shifts and Working at Night Act as Occupational Stressors Alter Redox and Inflammatory Markers

BACKGROUND

Studies of breast cancer etiology suggest evidence that night shift working and occupational exposure to ionizing radiation (IR) are defined risk factors for breast cancer development. There are few studies to clarify neuroendocrine and inflammatory status and the possible consequences particularly in occupational exposure.

AIM OF THE STUDY

Our aim was to associate the redox and inflammatory biomarkers with either nightshift working or occupational radiation exposure, and to compare their levels between the two groups at Alexandria University Hospitals, Alexandria, Egypt.

METHODS

We included 150 female nurses at Alexandria University Hospitals: 50 nightshift workers, 50 radiation workers, and 50 dayshift workers as a control group (neither work nightly nor radiation workers). In morning serum sample (7 am), we measured the concentrations of serum melatonin, Cortisol, tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) by ELISA; malondialdehyde (MDA) and total antioxidant capacity (TAC) levels colorimetrically, and C-reactive protein (C-RP) levels by turbidimetric method.

RESULTS

Nightshift workers had significantly lower levels of melatonin and TAC, and higher levels of serum inflammatory markers and cortisol, than day shift control group of workers. Workers occupationally exposed to IR had significantly higher levels of serum melatonin, MDA and inflammatory markers, lower levels of serum cortisol, and lower TAC than day shift workers.

CONCLUSION

Occupational exposure to IR and working nightly alter circulating redox and inflammatory biomarkers.

Occupational radiation procedures and doses in South Korean dentists

OBJECTIVES

Dentistry is among the occupations involving chronic exposure to ionizing radiation. Although several cohort studies on medical radiation workers have been conducted in some countries, only a few epidemiological studies on dentists have been performed to examine occupational radiation exposure worldwide. The aim of this study was to investigate occupational characteristics and radiation exposures in South Korean dentists.

METHODS

A total of 658 dentists were surveyed from April 2012 to May 2013, and survey data were linked with dosimetry data from the National Dose Registry. Multiple linear regression analysis was used to identify the relationship between demographic or occupational factors and individual radiation doses.

RESULTS

Of the dentists sampled, 78% were men, 51% were younger than age 40, and 61% began employment after 2000. The most frequent procedures performed by dentists were panoramic radiography, followed by intraoral and portable dental radiography. Male dentists were more frequently involved in radiation procedures, and a higher proportion of male than female dentists wore a lead apron for diagnostic radiology. The average annual effective dose was 0.18 mSv for male and 0.13 mSv for female dentists. Female dentists working in provincial areas had significantly higher average annual and cumulative effective doses than those in metropolitan areas. The cumulative effective doses were significantly greater for older dentists, those who entered the field in the 1990s, and those with longer employment duration.

CONCLUSIONS

Our findings provided detailed information on work practices, number of procedures performed on a weekly basis, and occupational radiation doses, which enabled in-depth evaluation of occupational radiation exposure and work status among dentists.

Radiation risk assessment in professionals working in dental radiology area using buccal micronucleus cytome assay

OBJECTIVE

The aim of this study was to assess the incidence of micronuclei (MN) in buccal mucosal cells of professionals working in radiology area to determine the risk of stochastic effects of radiation.

MATERIALS AND METHODS

All the professionals and students working in King Khalid University - College of Dentistry radiology area were included in the Risk Group (RG = 27). The Control Group (CG = 27) comprised of healthy individual matching the gender and age of the RG. Buccal mucosal scraping from all the 54 subjects of RG and CG were stained with Papanicolaou stain and observed under oil immersion lens (×100) for the presence of micronuclei (MN) in the exfoliated epithelial cells.

RESULTS

There was no significant difference between the incidence of MN in RG and CG (p = >0.05) using t-test.

CONCLUSION

Routine radiation protection protocol does minimize the risk of radiation induced cytotoxicity, however, screening of professionals should be carried out at regular intervals.

Bonding performance of different adhesive systems to deproteinized dentin: Microtensile bond strength and scanning electron microscopy

Deproteinization has been shown to optimize dentin bonding, but differences in adhesive composition should be considered. The objective of this study was to evaluate the effect of dentin deproteinization on microtensile bond strength (microTBS) of four total-etch adhesive systems (Single Bond/SB, Prime & Bond NT/PB, One Coat Bond/OC, and PQ1/PQ). The ultrastructure of the resin-dentin interfaces was also examined using scanning electron microscopy. Tukey's multiple-comparison tests indicated that PB and PQ produced significantly higher microTBS (p<0.05) after dentin deproteinization (PB=61.53 MPa, PQ=58.18 MPa). This treatment provided statistically lower results for SB (39.08 MPa), but the microTBS of OC to dentin was unaffected by dentin deproteinization. The bonding performance on deproteinized dentin surfaces depended on the characteristics of each adhesive system, as well as the adhesive dentin specificity to the oxidant effect of sodium hypochlorite. Incorporation of fillers in the adhesive, a possible self-etching action, and the presence of a volatile solvent (acetone) were the main factors for a better union between the adhesive system and deproteinized substrate.

Attitude of the Belgian dentist population towards radiation protection

OBJECTIVES

To perform a survey of private dental offices in Belgium and gain insight in the knowledge and attitude of Belgian dentists towards quality care in radiography and radiation protection.

METHODS

A questionnaire was distributed among 700 Belgian dental offices, which were included based on demographic data and the use of intraoral radiographic equipment.

RESULTS

The response rate was 71%. Implementation of standards for quality care and radiation protection was suboptimal. In most offices, exposure settings of the intraoral radiation tube were 65 kV/kVp to 70 kV/kVp and 10 mA to 12 mA, with an average exposure time of 0.45 s. No reduction of exposure time was noticed when using faster film types. About one-third of the responders worked with digital image receptors. Aiming devices and rectangular collimation were used in a minority of practices (40% and 6%, respectively). The distance of the dentist to the radiation tube during exposure was on average 2.2 m, although 8% of the dentists assisted in holding the image receptor inside the patient's mouth. One quarter of the dentists were standing behind a wall when taking radiographs. Lead aprons were worn more often by female dentists. Dose estimation revealed that male dentists received a significantly larger effective dose per year than female dentists (8.3 mSv vs 3.2 mSv).

CONCLUSIONS

The implementation of standards of quality care for radiography and radiation protection could be improved among Belgian dentists. An elaborate educational programme in dental radiography is a prerequisite. Furthermore, recommendations could help to attain a change in attitude towards the use of ionizing radiation in order to meet European guidelines.