Occupational Hearing Loss: What Dentists Need to Know

By Jaclyn Bewick, Au.D., CCC-A

The safety guidelines for dental professionals consist of some very important protective items: gloves, face masks, eye protection, and lab coats. The one item that does not get addressed during safety protocol training is our hearing. The need to protect hearing is typically a silent matter in the dental industry. As an audiologist, I want to take some time to focus on the importance of recognizing the potential effects of noise exposure in a dental office and how to protect your ears over time.

A standard for noise exposure has been developed to regulate hearing protection in noisy work environments. The Occupational Safety and Health Administration (OSHA) sets the legal limits of noise exposure in the workplace and creates guidelines for safety hearing measures. The Safety Standards and Guidelines by OSHA are based upon a worker’s time (measured in A-weighted decibels, abbreviated dBA) over an 8-hour day. It is important for anyone who works in noise to know that OSHA mandates use of hearing protection if a worker is exposed to noise levels at 85 dBA or above for 8 hours. Also, OSHA’s permissible exposure limit (PEL) in an 8-hour day is 90 dBA.7 For complete explanation of OSHA Safety Standards and Guidelines, please refer to Table 1.1.

Many research studies have argued that estimated noise levels in dental offices do not exceed OSHA standards because equipment is not used on a continual basis.4,8,9 But even though noise levels do not surpass the OSHA safety standards, prolonged exposure to noise produced in a dental office increases the risk for dental professionals to develop hearing loss later in life.

According to the National Institute on Deafness and Other Communication Disorders (NIDCD), noise-induced hearing loss is defined as hearing impairment that results from exposure to loud sound. In particular, sounds can cause damage to our ears when a person is exposed to an intense impulse sound (i.e. explosion) or exposure to loud sounds over a long, extended period of time.6 In short, cumulative noise exposure can damage your hearing slowly over time. Therefore, it is important to recognize the potential damage to hearing and create an educated practical strategy to protect your ears.

Hearing loss as a result to noise exposure depends upon a combination of the duration of noise and the intensity of the sound. Intensity refers to the loudness of the sound source and duration refers to the length of time exposure to a sound source occurs. Over time, exposure to your loud noisy instruments will play a role in damaging your hearing.

As a dentist, you are exposed to sounds measured at approximately 85–90 dB or above on a regular basis with use of dental instruments and other equipment.1, 8 To put this level in perspective, 85–90 dB is as loud as a food blender, subway, passing heavy city traffic, or motorcycle use. Different instruments used in your office, will measure at varying sound levels. High speed handpieces tend to range from 82 dB–103 dB. Ultrasonic Scalers have a big range from 83 dB–107 dB. Low speed handpieces range from 70–74 dB. High speed suction ranges from 72–75 dB.1,8,9

Dental equipment may only be utilized from ten minutes to two hours total in a day, but the effects over years can contribute to hearing loss. Researchers have shown a significant relationship between hearing loss and dental practitioners with exposure to loud equipment over a 15-year career and older than 40 years.3 It has also been discussed that dentists with at least ten years of practice who routinely utilize loud dental instruments are at a greater risk for developing a hearing impairment. Some research even shows that dental practitioners who use loud instruments (i.e. high-speed dental handpieces) on a regular basis had worse hearing when tested than those who do not use dental equipment.5 Short periods of exposure to such intensity of sound over a short time frame produce little to no risk of developing hearing loss but extended exposure of such loud equipment, can result in great risk in damaging the ears.

As a dentist, you cannot eliminate exposure to loud equipment but you can protect your ears from the exposure of the noisy, high frequency sounds of dental equipment. Use of hearing protection devices and regular maintenance of dental equipment can help protect the ears.2,5,8,9

Hearing Protection Earplugs

The easiest way to protect the ears is with hearing protection earplugs. Hearing protection can be divided into two categories: Non-custom or custom devices. It is important to note that both non-custom and custom devices allow for the same amount of hearing protection from loud sounds if worn properly in the ears. When choosing hearing protection, consider which item will properly seal the ear for the most efficient protection from noise and which item will allow for both reduction of loud noise and effective communication.

1) Non-custom earplugs

Traditional non-custom devices provide users with a choice of single-use earplugs (polyurethane foam or PVC foam) or multiple-use earplugs (silicone, polyvinyl or other types of plastic or rubber). Single-use earplugs are disposable and roll down for easy insertion into the ear. Whereas, multiple-use earplugs are reusable and made with flexible flanges to easily insert into the ears without rolling. They can be washed with soap and warm water to allow for multiple uses.

Traditional non-custom earplugs are great for noise reduction but can result in speech to sound muffled. Because they compromise conversations with co-workers and patients, many dental practitioners do not like to wear them.

A newer solution for non-custom devices is considered a more active form of hearing protection. It is a small device that fits in the ear canal and runs on hearing aid batteries (lasts about two weeks). This device automatically compresses loud sound levels when heard but once the dangerous sound levels stop, the compression dissipates. This automatic feature allows the user to obtain both effective communication and noise reduction.

This type of device does have several selections of silicone foam plugs to place on the end of the device to help with more of a personalized fit.

2) Custom filtered earplugs

Custom earplugs with filters are designed to provide individuals with a comfortable yet effective hearing protection solution. These earplugs are obtained at an audiologist’s office in which impressions are taken for each ear in order to procure an exact replica of the ear and ear canal; a very similar process in how dental impressions are obtained. The impression is sent to an earmold manufacturer to be made into a custom silicone earplug.

These customs earplugs are designed with small filters to help maintain the full range of sound while protecting the hearing from loud sounds. The filters in the earplugs lowers the sound levels evenly across all frequencies to create a balance between communication and hearing protection.

Maintenance of Equipment

It has been measured that used and older dental equipment is louder than newer devices. Improvements in technology with dental instruments have reduced some of the noise levels and can help maintain a safer work environment; however, if equipment is not maintained properly, the instruments are noisier.5,8,9 Handpieces tend to wear out and become louder if not maintained properly. Periodic checks on equipment should be completed to make sure parts are running well and not worn out.

Conclusion

Overall, even though noise exposure in the office is minimal and does not surpass OSHA standards, it is important that dentists recognize that there is potential for noise-induced hearing loss to occur. Due to extended exposure over several years, a potential for hearing loss is greater. With use of proper hearing protection and maintenance of dental instruments and equipment, dentists can help protect their hearing. The main goal is to help reduce the risk of hearing loss and provide a focus on hearing health and exposure of noise levels in the world of dentistry.

References
1. Grover, A., RDH. (2018, August 25). Hearing Loss in Dentistry: A Silent Topic. Retrieved June 23, 2019, from https://www.todaysrdh.com/hearing-loss-dentistry-silent-topic/
2. Guigno, A. (2016, June 18). Can you hear me now? Hear about occupational noise-induced hearing loss among dental professionals. Retrieved from https://www.rdhmag.com/career-profession/students/article/16409266/can-you-hear-me-now-hear-about-occupational-noiseinduced-hearing-loss-among-dental-professionals
3. Khaimook, W., Suksamae, P., Choosong, T., Chayarpham, S., & Tantisarasart, R. (2014, September). The prevalence of noise-induced occupational hearing loss in dentistry personnel. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/25650469
4. Lehto, T. U., Laurikainen, E. T., Aitasalo, K. J., Pietila, T. J., Helenius, H. Y., & Johansson, R. (1989). Hearing of dentists in the long run: A 15-year follow-up study. Community Dentistry and Oral Epidemiology,17(4), 207–211. doi:10.1111/j.1600-0528.1989.tb00613.x
5. Messano, G. A., & Petti, S. (2012, June 29). General dental practitioners and hearing impairment. Retrieved from https://www.sciencedirect.com/science/article/pii/S030057121200173X
6. Noise-Induced Hearing Loss. (2019, June 14). Retrieved from https://www.nidcd.nih.gov/health/noise-induced-hearing-loss
7. OSHA Guidelines and Standards. (n.d.). Retrieved from https://www.osap.org/page/GuideOSHA
8. Setcos, J. C., & Mahyuddin, A. (n.d.). Noise Levels Encountered in Dental Clinical and Laboratory … Retrieved from https://www.researchgate.net/publication/13574919_Noise_Levels_Encountered_in_Dental_Clinical_and_Laboratory_Practice
9. Theodoroff, S., & Folmer, R. (n.d.). Hearing loss associated with long-term exposure to high … Retrieved from http://thedoctorsearplugs.com/wp-content/uploads/2018/03/GenDent_MJ15_Folmer.pdf

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