Effects of Ultrasonic Use on Hearing Loss in Dental Hygienists: A matched pairs design study.

Dental professionals are exposed to hazardous noise levels on a daily basis in clinical practice. The purpose of this study was to compare the hearing status of dental hygienists who utilize ultrasonic scalers in the workplace compared to age-matched control participants (non-dental hygienists) who were not exposed to ultrasonic noise. A convenience sample of nineteen dental hygienists (experimental) and nineteen non-dental hygienists (control) was recruited for this study. A matched pairs design was utilized; participants in each group were matched based on age and gender to eliminate confounding variables. The testing procedure consisted of an audiologist performing a series of auditory tests including otoacoustic emissions test, pure-tone audiometry, and tympanometry on the experimental and control groups. In the right ear, there were notable differences from 1000 Hz - 10,000 Hz and in the left ear from 6000 Hz - 10,000 Hz, with higher hearing thresholds in the experimental group of dental hygienists. While 56% of the univariate tests conducted on how many days were worked per week showed statistical significance, the regression line slope indicated those that worked more days had better hearing statuses. The variables for years in practice for dental hygienists, how many of those years were full-time employment, and how many years the dental hygienist had used an ultrasonic scaling device, also had many significant univariate tests for the experimental group only. These variables were more likely to serve as proxies representing true noise exposure. The paired t-test between the groups demonstrated statistically significant differences between the experimental and control group at 9000 Hz in both ears. While results from this study demonstrated various qualitative differences in hearing status of the control group (non-dental hygienists) and experimental group (dental hygienists), age was found to be the most critical variable. Furthermore, this data demonstrated differences in hearing status based on various frequencies between dental hygienists and age-matched controls that should be further explored with a larger population.