Biological tests on an experimental glass ionomer (silicopolyacrylate) cement

The biological compatibility of an experimental glass ionomer (silicopolyacrylate) cement has been assessed in in vitro (cell culture) and in vivo (monkey teeth) tests. For comparison a conventional silicate cement (Super Syntrex) was included in the in vivo experiments. In vitro, the glass ionomer cement was toxic when freshly prepared. The toxicity decreased, however, with increasing setting time. In experiments with prolonged cell-material contact time with specimens which had set for 24 h, the material appeared to be non-toxic. The in vivo experiments confirmed previous reports concerning unfavourable pulp reaction caused by silicate cement, while the glass ionomer cement caused mainly a mild pulp reaction after 8 days of observation. Unfortunately no longer-term observations were obtained since the material had been washed out of the cavities within 36 days.

Cell markers, cytokines, and immune parameters in cement mason apprentices

OBJECTIVE

Cement masons are known to have significant silica exposure, and silica exposure and silicosis are thought to increase risk of autoimmune disease. Because the mechanisms remain obscure, with inconclusive reports of systemic immune effects following silica exposure, our goal was to identify potential early markers of silica-related immunologic and respiratory effects.

METHODS

We conducted a cross-sectional study of cement mason apprentices and electrician (control) apprentices. Demographics, dust exposure history, symptoms, spirometry, exhaled nitric oxide, and blood (for immunoglobulins, cytokines, cell counts, and surface markers) were obtained from 11 cement mason apprentices and a comparison group of 21 electrician apprentices.

RESULTS

Masons had significantly higher (P < 0.05) masonry dust exposure (42 versus 9 dust-hour-years), serum interleukin-1beta (IL-1beta; 12 versus 9 pg/ml), IL-2 (20 versus 8 pg/ml), IL-4 (193 versus 67 pg/ml), IL-10 (44 versus 21 pg/ml), and interferon-gamma (139 versus 65 pg/ml) compared with electricians. In contrast, masons had significantly lower percentages of CD25+ (12% versus 20%) and CD69+ (4% versus 9%) lymphocytes.

CONCLUSION

Mason apprentices had higher levels of serum proinflammatory cytokines and lower percentages of CD25+ and CD69+ lymphocytes than did electrician apprentices. These preliminary findings suggest that mason apprentices may be at greater risk of a systemic proinflammatory state that is potentially linked to immune dysregulation. Although distinct limitations of this preliminary data are recognized, this is consistent with early biologic effects leading to increased incidence of autoimmune disease among silica-exposed workers. Prospective studies are needed to validate these initial findings and clarify the temporal sequence of observed relationships.

Mortality and cancer morbidity among cement workers

OBJECTIVE

To explore associations between exposure to cement dust and cause specific mortality and tumour morbidity, especially gastrointestinal tumours.

DESIGN

A retrospective cohort study.

SUBJECTS AND SETTING

2400 men, employed for at least 12 months in two Swedish cement factories.

MAIN OUTCOME MEASURES

Cause specific morality from death certificates (1952-86). Cancer morbidity from tumour registry information (1958-86). Standardised mortality rates (SMRs; national reference rates) and standardised morbidity incidence rates (SIRs; regional reference rates) were calculated.

RESULTS

An increased risk of colorectal cancer was found > or = 15 years since the start of employment (SIR 1.6, 95% confidence interval (95% CI) 1.1-2.3), mainly due to an increased risk for tumours in the right part of the colon (SIR 2.7, 95% CI 1.4-4.8), but not in the left part (SIR 1.0, 95% CI 0.3-2.5). There was a numerical increase of rectal cancer (SIR 1.5, 95% CI 0.8-2.5). Exposure (duration of blue collar employment)-response relations were found for right sided colon cancer. After > or = 25 years of cement work, the risk was fourfold (SIR 4.3, 95% CI 1.7-8.9). There was no excess of stomach cancer or respiratory cancer. Neither total mortality nor cause specific mortality were significantly increased.

CONCLUSIONS

Diverging risk patterns for tumours with different localisations within the large bowel were found in the morbidity study. Long term exposure to cement dust was a risk factor for right sided colon cancer. The mortality study did not show this risk.

Cytotoxicity of partial-stabilized cement

Partial-stabilized cement (PSC) is a kind of modified calcium silicate cement used for root-end surgery. Minor transition metal elements Co, Cr, and Zn were added for enhancing the setting property of to PSC. In our previous study, minor transition metal additions greatly improved the setting property of PSC. However, the concern of metal toxicity was raised, as the material would be used in the human body. In this study, we evaluated the cytotoxicity of PSC in comparison with mineral trioxide aggregate (MTA), which is one of the commercialized materials used for dental root-end filling. Primary osteoblast cell was used as the target cell. Cell proliferation, cytotoxicity, viability, function, and senescence were analyzed. The cytotoxicity of the PSC-Zn group (PSC with Zn addition) was similar to that of MTA. PSC-Zn is not only nontoxic at the cellular level but also has adequate mechanical property, which makes it a potential root-end filling material for apical surgery.

Wet cement: a poorly recognized cause of full-thickness skin burns

Cement is a rare cause of full-thickness burns. We have examined the aetiology, frequency and severity of these burns, and assessed public awareness of the potential of cement as a caustic agent. Of patients, 95 per cent were unaware of the potential of cement to cause burns, and none had seen precautionary warnings on cement bags or delivery dockets. Factors important in burn production appear to be alkalinity, duration of contact and the abrasive nature of the cement particles. It is concluded that doctors, especially casualty officers, should know of the potential of progressive full-thickness burns from wet cement. General public awareness should be increased. The cement manufacturers were asked to comment on the content of this paper.

Histological type of lung carcinoma in asbestos cement workers and matched controls

Histological types of lung carcinoma were examined in a case series of workers exposed to asbestos cement dust (n = 29) and matched controls (n = 87). The proportion of adenocarcinomas was 31% among the exposed subjects and 15% among the controls (mid-p = 0.05). Among workers with high exposure the proportion of adenocarcinoma was even higher (45%, 5/11; mid-p = 0.03). The proportion of peripheral tumours tended to be higher among exposed cases than controls (24 v 12%, mid-p = 0.12). Lobe of origin did not differ, however, between exposed cases and controls. Thus the study indicates an association between the degree of exposure to asbestos and adenocarcinoma of the lung, and a peripheral rather than central localisation of the tumours, but with virtually the same distribution of lobe of origin as in the general population.

[Lung cancer mortality in Casale Monferrato (Italy) and attributable risk to occupations in the asbestos-cement production]

The study presents mortality rates for lung cancer in the town of Casale Monferrato, where the largest Italian asbestos cement-plant was located. Cases of lung cancer dying in 1989-94 were exhaustively searched for in the register of deaths. Each case of lung cancer has been identified as ever or never employed in the factory with a linkage to the rosters of employees in the plant. Women were also identified as ever or never married to an asbestos-cement worker. The number of person-years at risk for asbestos cement workers and their wives was measured on the basis of the most recent follow-up. Mortality rates were computed separately for those exposed (workers and wives of workers) and for those with no evidence of exposure. Mortality rates for non-exposed were similar to rates in Piedmont (the region where Casale is located). The relative risk (ever exposed vs. never exposed) was 2.8 among men and 2.1 among women. Attributable risk among the exposed was 64.5% for men and 53.1% for women while among the general population it was 18.1% for men and 13.2% for women. The study confirms the dramatic effect of occupational asbestos exposure in Casale Monferrato but does not suggest an increase in lung cancer mortality among people with no occupational activity in the asbestos-cement production.

[Epidemiologic studies. I. Secondary caries in tooth areas restored by silver-tin-amalgam, silicate cement or inlays]

On the basis of epidemiologic studies on 10 106 sugjects from the population of the town of Rostock, the authors deal with the frequency of filled tooth areas and their affection by secondary caries with special regard to filling materials (silver-tin amalgam, silicate cement, inlay). The low frequency of secondary caries in tooth areas restored by means of inlays is noteworthy. Finally, the authors give recommendations for practice.

[Cause-specific mortality of asbestos-cement workers compensated for asbestosis in the city of Bari]

The cause-specific mortality of 233 asbestos cement workers employed by the Fibronit company in Bari and compensated for asbestosis was investigated. Cohort members were enrolled on 31.12.1979 and followed through 30.4.1997; follow-up was completed for 98.3% of study subjects, and causes of death were ascertained for 96.6% of deceased subjects. Observed mortality was contrasted to that expected according to cause-sex-age- and calendar time-specific rates of the population resident in the Apulia Region. All causes observed mortality exceeded expected value (SMR: 117, 87 observed), due to a significant' increase in pneumoconiosis (SMR: 11238, 14 observed) and malignant neoplasms (SMR: 163, 38 observed)). A significant decrease of circulatory diseases was found (SMR: 64, 18 observed). Among cancer deaths, the following sites showed a significant excess: lung (SMR: 206, 17 observed), pleura (SMR: 2551, 4 observed), mediastinum (SMR: 2367, 2 observed) and peritoneum (SMR: 2877, 2 observed). The excess mortality due to asbestosis, respiratory cancer and peritoned neoplasms can be causally attributed to occupational asbestos exposure.

[The irritant effect of plastic filling materials on the dental pulp]

The irritating effect of amalgams, silicate cement, methyl methacrylate, composites, and glass ionomer cement on animal and human dental pulp was discussed. If the foundation is appropriate, pulpal alterations can be reduced or even eliminated.