Methods: After approval by the ethics committee, 52 dentists and 52 other academic professionals (control group) were enrolled. Exclusion criteria were colds, ear-blockages or abnormal hearing-thresholds. In all subjects an audiometric determination (Oscilla® USB audiometer, AudioConsole 3, Inmedico A/S, Denmark) was performed in the frequency range of 125Hz to 8kHz for both ears. All subjects filled in a questionnaire concerning anamnestic data and number of years in the profession. Differences between groups were analyzed with the Mann-Whitney U-test and linear regression analysis.
Results: A total of 104 subjects (68% male, 32% female) with a mean age of 51.2 years (SD: 9 years) participated in this study. In the frequency range of 4-8kHz for the left ear hearing loss of up to 26dB and for the right ear of up to 24dB were found in both groups. Age and gender showed a slight hearing loss of the dentists according to the linear regression analysis with the co-variables. For example at 0.75 kHz they had a loss of 14.9dB on the left side (right side 16.3dB), while in the control group the values were 12.7dB for the left ear (right side 12.2dB). These differences were statistically significant (p=0.026).
Conclusions: Dentists showed only a slight hearing loss in the frequency range from4-8 kHz. However, hearing impairment in dentists was higher than in controls. Since other factors were comparable in both groups, occupational exposure to high-speed hand pieces and other noisy tools might be responsible. Therefore, high-quality equipment should be used in dental practices and regular control hearing tests are recommendable.