Effects of occupational environmental controls and work management on chromosomal damage in dental technicians in Japan

Determination of cytogenetic abnormalities in buccal mucosa of dental laboratory technicians

This study aims to investigate the toxic effects of metals, which dental technicians are exposed to, on the oral mucosa cells in dental prosthesis laboratories (DPL). To monitor cytotoxic effects, mutations of pyknosis, Karyolysis Karyorrhexis, binucleus, micronucleus, and broken-egg were evaluated. Experimental group comprised of a total of 30 volunteer DPL employees from various DPLs, and 30 teachers and office workers were volunteered to be a part of the control group. Age range of DPL employees and whether they consume alcohol or smoke cigarettes were also considered as sub-variables. Peripheral smear technique was applied by taking samples from the oral mucosa of the experimental group and the control group. Anomalies determined between technicians and control group were statistically significant (p < .05). However, our findings revealed that the sub-variables (ie, age range, alcohol, and smoking) did not significantly affect the anomalies.

Association between presence of 20 or more natural teeth and all-cause, cancer-related, and cardiovascular disease-related mortality: Yamagata (Takahata) prospective observational study

BACKGROUND

Several studies have surveyed the relationship between the presence of ≥ 20 natural teeth and mortality. However, very few have evaluated this association over a long-term follow-up of more than ten years within a large population in Japan. This study aimed to prospectively confirm the associations between mortality and the presence of ≥ 20 natural teeth within a community-based population in Japan.

METHODS

A prospective observational study including 2208 participants aged ≥ 40 years was conducted in Takahata Town, Japan, between May 2005 and December 2016. All participants answered a self-administered questionnaire to provide their background characteristics, including their number of teeth. The participants were classified into two categories based on their self-reported number of teeth (< 20 and ≥ 20 teeth). Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional-hazards regression model to assess risk factors for all-cause, cancer-, and cardiovascular disease-related mortality.

RESULTS

The total follow-up period was 131.4 ± 24.1 months (mean ± SD). After adjusting for covariates, the risk of all-cause mortality was significantly higher in the group with < 20 teeth than in those with ≥ 20 teeth (HR = 1.604, 95% CI 1.007-2.555, p = 0.047). However, the risk of cancer- and cardiovascular disease-related mortalities was not statistically significant between the two groups.

CONCLUSION

In this study, participants with < 20 teeth had a significantly higher risk of all-cause mortality, although the difference was borderline significant. These results emphasize the importance of having ≥ 20 natural teeth for a healthy life expectancy.

Assessment of occupational exposure to fine particulate matter in dental prosthesis laboratories in Kocaeli, Turkey

Dental prosthesis laboratories (DPLs) are among the workplaces where predominantly manual production takes place. In such working environments, during the manual manufacturing process, which involves fine smoothing and polishing of dental prostheses, fine particulate matter is released into the ambient air. In this study, the particulate matter (PM) concentrations and elemental content of the fine particles in the working ambient air were identified in six DPLs in Kocaeli, Turkey. PM_2.5 mass concentrations, measured in all the DPLs, ranged between 80.8 and 1645 μg/m³ (mean 414 ± 406). As a result of the analyses performed with an ICP-MS device (Perkin Elmer Elan®DRC-e), trace elements of Be, Cd, Hg, and, notably, Co, Cr, Mo, and Ni were found. The researchers calculated the excess lifetime cancer risks and total hazard indexes. The average total cancer risk for all the DPLs was 8 × 10^-3, which is higher than the acceptable limit of 1.0 × 10^-6, and the total hazard index was 187, which is greater than the acceptable limit of 1.0. Considering these high-level risks, the study concluded that there is a need for new production methods, and strict application of occupational health and safety measures, to reduce the fine particle exposure of the workers in the laboratories. In addition, there are prescribed limit values for particulate matter only for respirable particles in working environments. The establishment of limit values, especially for PM_2.5 concentrations, is important for the protection of the health of the employees.

Fewer teeth are a risk factor for being underweight in community-dwelling Japanese aged 40 years and older: The Yamagata (Takahata) Study

OBJECTIVE

The aim of the present study was to investigate comprehensively, the risk factors for underweight in cross-sectional study in the general population of Japan.

METHODS

The survey population was the general population of individuals aged >40 years in Takahata town, Japan in 2005. A postal survey in the form of a self-administered questionnaire was distributed, and 6084 individuals were entered into the final statistical analysis. The self-administered questionnaire contained items regarding lifestyle, oral health status, socio-economic status and dietary intake. To examine the independent relationships between an underweight status and several parameters, a multivariate logistic regression analysis was used to estimate adjusted odds ratios (ORs).

RESULTS

The number of teeth, age, alcohol consumption, hypertension, spousal status, smoking habit, appetite, body weight at 20 years of age, habit of going out and physical activity were independently associated with an underweight status compared with the normal weight group. Individuals with fewer than 10 teeth were especially more likely to be underweight than individuals with more than 20 teeth (OR = 1.956, 95% CI = 1.261-3.035).

CONCLUSION

This study showed an independent association between the number of teeth and an underweight status, indicating that fewer teeth can increase the risk of being underweight.

Possible benefits of tomato juice consumption: a pilot study on irradiated human lymphocytes from healthy donors

Background

Reactive oxygen species (ROS) mediate much of the DNA damage caused by ionizing radiation. Among carotenoids, lycopene and β-carotene, present in tomato juice, are known to be strong radical scavengers. The aim of the study was to investigate the effect of tomato juice intake on the levels of DNA damage and oxidative stress in human whole blood induced by in vitro exposure to X-rays.

Methods

Ten healthy adults were asked to drink 190 g of tomato juice, containing 17 mg lycopene and 0.25 mg β-carotene, per day for 3 weeks and then refrain from drinking it for 3 weeks. Peripheral whole blood samples were collected before and after the intake period of tomato juice and after the washout period. The blood samples were exposed in vitro to X-ray doses of 0, 0.1, 0.5, and 2 Gy. Cytogenetic damage was measured using the cytokinesis-block micronucleus (CBMN) assay and the dicentrics (DIC) assay. The level of oxidative stress was determined using serum 8-oxo-7, 8-dihydro-2-deoxyguanosine (8-oxo-dG) and plasma reactive oxygen metabolite-derived compounds (d-ROMs). The concentration of carotenoids in plasma was measured at the three time points.

Results

The levels of 8-oxo-dG tended to decrease during the intake period and increase during the washout period. A non-significant inverse correlation was noted between the plasma concentration of lycopene plus β-carotene and the level of 8-oxo-dG (P = 0.064). The radiation-induced MN and DIC frequencies increased in a dose-dependent manner, and when compared at the same dose, the MN and DIC frequencies decreased during the intake period compared with those at baseline and then increased during the washout period. The results suggest that continuous tomato juice consumption non-significantly decreases extracellular 8-oxo-dG, d-ROMs, and MN. Tomato juice intake had minimal or no effect on radiation-induced 8-oxo-dG and d-ROMs. For most radiation doses, continuously tomato juice intake lowered the levels of MN and DIC.

Conclusion

Tomato juice consumption may suppress human lymphocyte DNA damage caused by radiation, but further examination is required.

Trial registration

2014-001 and 2014-R06.