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Background: Rotating instruments in dentistry are radiating an unpleasant high-frequency noise, which was supposed to produce hearing loss by its loudness. Therefore frequently notifications and recognizing procedures were initiated because of the suspicion of occupational noise-induced hearing loss (German listing for occupational diseases as given by decree: Number 2301). In recent years dentists, dental technicians and dental assistants repeatedly had to be tested because of a suspicion for noise-induced inner ear damage., Methods: Noise measurements were performed in 3 working places of dentists and 7 dental laboratories., Results: In regard to dentists and dental assistants it was found that the aspirator, not the rotating instruments, was the most intense source for noise in the office. The averaged daily noise level was measured between 70 and 77 db(A) and was therefore obviously below the inner ear damaging limit of 85 dB(A). For dental technicians the on-site related averaged daily noise level was about 68 dB(A) and the person related averaged daily noise level was about 76 dB(A). In some particular cases 80 dB(A) were exceeded, but relevant levels for an occupational noise trauma were not reached. It has to be taken into consideration that the rotating instruments got a considerable noise reduction in the last decade. Additionally it has to be taken into account for the calculation that the averaged running time of rotating instruments is 30 minutes per day in the office. Therefore, a notification or a recognizing procedure can regularly stand aside., Conclusion: An endangering by noise as given by the German occupational disease decree (more than 85 db(A)) cannot usually be expected for the dentist, the dental assistant and the dental technician.

Though endomyocardial biopsy has remained the gold standard for diagnosing acute cardiac rejection (AR), this invasive method does not provide adequate means for close monitoring of the rejection process. In order to assess the usefulness of M-Mode- and two-dimensional (2D) echocardiography for the noninvasive diagnosis of AR in heart transplant recipients on cyclosporin, 45 patients (mean age 40.6 +/- 8.8 years, 19.9 +/- 14.4 months postoperatively) were evaluated prospectively. Mean observation time was 9.1 +/- 4.8 months. Echocardiographic examination techniques were strictly standardized; besides measurements of left (LV) and right ventricular (RV) diastolic wall thickness and of the isovolumic relaxation time, computerized frame-by-frame-analysis was applied to LV short axis cross sections for the determination of diastolic cavity cross-sectional area and extent and mean velocity of systolic and diastolic area change. To account for technical and biological variability, 95%-confidence limits were calculated for each parameter from two rejection-free examinations, allowing identification of significant changes during AR. In this study, 36 biopsy-proven AR occurred in 19 patients. Compared to control values, mean heart rate increased from 86.2 +/- 10.2 to 94.6 +/- 15.1 b/min (p less than 0.05), diastolic septal + posterior wall thickness from 21.2 +/- 4.1 to 24.9 +/- 6.2 mm (p less than 0.001) and RV free wall thickness from 6.3 +/- 1.1 to 8.9 +/- 1.8 mm (p less than 0.001). Isovolumic relaxation time decreased from 73.2 +/- 14.4 to 54.8 +/- 16.6 ms (p less than 0.001), diastolic cross-sectional area from 12.8 +/- 2.0 to 11.1 +/- 2.2 cm2 (p less than 0.05), relative area change from 65.8 +/- 9.8 to 49.1 +/- 14.4% (p less than 0.001) and systolic and diastolic area change velocities from 28.1 +/- 7.8 and 41.8 +/- 8.5 cm2/s to 18.9 +/- 5.6 and 28.6 +/- 9.2 cm2/s, respectively (p less than 0.001). Though significant changes occurred during AR, most measurements remained within the normal range. Thus, in individual patients, AR could only be suspected in comparison to the control measurements. None of the examined parameters allowed to establish the diagnosis of AR in all instances. However, when the measurements of all parameters were considered together, 35 of the 36 AR diagnosed by biopsy could also be identified by echocardiography, including all requiring intensified immunosuppressive therapy. Mild AR was not always detected, and the differential diagnosis between LV hypertrophy and AR required an endomyocardial biopsy in some instances.(ABSTRACT TRUNCATED AT 400 WORDS)