Introduction & Objective: Methyl methacrylate (MMA), as a monomer of acrylic resin that has a wide variety of usages in denture fabrication, is considered as an air pollution indicator in the laboratories. Occupational exposure to these compound vapors can cause respiratory hypersensitivity, occupational asthma, eye and skin irritation and Allergic Contact Dermatitis (ACD). Therefore control of MMA exposure may promote the personnel’s health. The aim of this study was to determine the relationship between spirometric disorders and methyl methacrylate in dental laboratories personnel.

Materials & Methods: In this case control study, exposure of time-weighted average (TWA) and short-term exposure level (STEL) were measured with MMA vapors in 39 randomly selected male employee (case group) in 25 denture fabrication laboratories in Hamadan city. The air samples were collected by sorbent tubes containing chromosorb (XAD2( and analyzed by gas chromatograph equipped with FID detector based on NIOSH method. In addition 30 men whitout occupational exposure to air pollutants (control group) were selected to compare the variation of spirometric parameters. Spirometric parameters of the case and control groups such as FVC, FEV1, FEV1/FVC and FEF25-75 were measured by Vitalograph spirometer (model: 2120) on ATS method, after the standard questionnaire of respiratory diseases had been completed during an interview and medical examination.

Results: The mean of MMA concentration was 132.87 ± 220.67 ppm for STEL and 1.95 ± 3.59 ppm for TWA.The relationship between MMA concentration in the STEL and TWA exposures was significant (P<0.05) and the relationship between MMA concentration and ventilation was significant just for STEL. In this study no relationship between MMA concentration and spirometric parameters in both STEL and TWA exposures was found. Also there was no significant difference between spirometric parameters of the case group and normal values of the control group. Only two cases of obstructive lung function decrease (5.13%) one case of macula (2.56%) and five cases of xerodermatitis (12.8%) were observed among the dental laboratory personnel.

Conclusion: The results showed that spirometeric tests are not enough to screen respiratory diseases in dental laboratory personnel as a measurement in prevention and health monitoring program. In order to control the exposures, specially in case of STEL, this study emphasizes, like the other studies, on biological monitoring, installing local ventilation systems in the laboratories and educating the personnel to correctly use suitable personal protective equipments