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Year : 2014  |  Volume : 3  |  Issue : 4  |  Page : 244-247

Assessment of noise levels in clinical and laboratory areas of dental teaching institution, Ahmedabad

1 Department of Public Health Dentistry, Siddhpur Dental College and Hospital, Gujarat, India
2 Department of Public Health Dentistry, Ahmedabad Dental College and Hospital, Gujarat, India
3 Department of Public Health Dentistry, Government Dental College and Hospital, Jaipur, Rajasthan, India

Date of Web Publication16-Oct-2014

Correspondence Address:
Sujal M Parkar
B-25 Krishna Bunglows I, Gandhinagar Highway, Motera, Ahmedabad-380 005, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2278-344X.143064

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Aim: To measure and assess the noise levels produced by different dental equipments. Materials and Methods: Measurement of the noise level was performed in preclinics, clinics, and dental laboratory of different departments of Ahmedabad Dental College and Hospital. The noise levels were determined using a Mini sound meter (CEM USA), which was placed at the dentist's and laboratory technician's ear level and at a distance of 1 m from a main noise source. The level of noise was measured in decibel (dB) while the instruments were at maximum running speed. Results: In dental laboratory, the nosiest dental equipment was gypsum lathe trimmer with the noise level ranging from 87.36 to 98.3 dB. In preclinical area, the sound produced by low-speed air-rotor ranges from 66.68 to 69.28 dB. In clinical areas, the highest noise produced was by high-speed air-rotor (73.36 to 81.8 dB). The noise created by suction pump when in contact with mucosa was in range from 73.1 to 80.32 dB. The noise levels generated during cutting were significantly higher (P < 0.05) than those of noncutting, which was proved in the course of the measurements. Conclusion: At the end of the study it can be concluded that the sound levels are below that causes damage to the human ear (85 dB). However, dental technicians and other personnel working all day in noisy laboratories could be at risk of Noise-Induced Hearing Loss if they did not choose not to wear ear protection.

Keywords: Dental clinic, dental equipments, dental laboratory, hearing loss, noise

How to cite this article:
Parkar SM, Parekh SH, Shah LM, Sharma AS. Assessment of noise levels in clinical and laboratory areas of dental teaching institution, Ahmedabad. Int J Health Allied Sci 2014;3:244-7

How to cite this URL:
Parkar SM, Parekh SH, Shah LM, Sharma AS. Assessment of noise levels in clinical and laboratory areas of dental teaching institution, Ahmedabad. Int J Health Allied Sci [serial online] 2014 [cited 2023 Dec 5];3:244-7. Available from: https://www.ijhas.in/text.asp?2014/3/4/244/143064

  Introduction Top

A sound, agreeable or disagreeable, is a stimulus discerned by the sense of hearing. Disagreeable or undesired sounds are described as noises, which may cause undesirable masking of sounds, may interfere with speech and communication, may produce pain, injury, and brief or perpetual loss of hearing. [1] The National Institute for Occupational Safety and Health has recognized noise pollution as one of the 10 leading causes of work-related disease and injuries. [2],[3]

High sound levels have a negative effect on extra-auditory systems with physical consequences (quickened pulse, increase in blood pressure, constriction of blood vessels, etc.) and psychical consequences (nervousness, mental fatigue, emotional frustration, low productivity, etc.). These effects occur especially with noise levels above 80 decibel (dB) and are dependent on the intensity, the distance to the source, the total duration of the noise, the age of the individual, and his/her physical condition and sensitivity. [4] Also, prolonged exposure to noise at 160 dB can induce permanent loss of hearing. [5] It is therefore essential to control noise in working environments.

In dentistry, research shows that dentists and dental auxiliaries are exposed to high noise levels for extended periods while working in dental clinics and laboratories. [4],[6],[7],[8] Such a high level of noise has a significant effect upon the hearing health of dentists and dental auxiliaries. [9] Hence, this study was undertaken to measure and assess the noise levels produced by different dental equipments in a clinic, preclinic, and dental laboratory in a dental institution, to determine if the noise level exceeds health limits and also to recommend improvements if noise levels are not within permissible limits.

  Materials and methods Top

A cross-sectional study was conducted to assess noise levels in clinics, preclinics, and dental laboratory at the Ahmedabad Dental College and Hospital, Ahmedabad Gujrat, India.

The sound levels were measured with a Mini sound level meter (CEM, USA) and a half-inch electrets condenser microphone. The frequency of this instrument ranges from 31.5 Hz to 8 KHz and the measuring level ranges from 40-130 dB. The microphone was placed at ear level and at a distance of 1 m from a main noise source to simulate the auditory position of the operator (dentist). The noise levels were measured over a 30 s interval. All the readings were noted by two investigators (PS and SL). The investigators were calibrated by training sessions in the correct use of the Mini sound level meter. At all times, the Mini sound level meter was used according to manufacturer's recommendations. The measurements were taken with only the equipment turned on (without cutting) and during cutting operations (on teeth, metal, acrylic resin, and ceramic). The level of noise was measured while the instruments were at maximum running speed.

The sound levels measured in different areas of dental institution were those produced by the procedures mentioned as follows:

  • Prosthetic laboratory - Laboratory activities involving the use of mounted metal trimmer, acrylic trimmer, and ceramic trimmer was assessed. Also assessed was the level of noise produced while denture polishing
  • Gypsum laboratory - Activities of cutting and vibration of gypsum
  • Preclinics - Activities mostly comprise the use of slow-speed air-rotors turned on only and during cutting acrylic teeth in phantom head
  • Clinics - Activities involving the use of ultrasonic Scalers and the use of high-speed air-rotors used while cutting tooth structure with or without suction pump and suction pumps running free and when they touch mucosa were measured for noise levels.

The characteristics of the equipment measured in each area are noted in [Table 1].
Table 1: Detail of the equipments measured

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Statistical analysis

For reproducibility, each measurement was repeated five times. The readings for both minimum and maximum levels were noted. The average of the five maximum readings was calculated and taken as the sound level for that particular equipment in dB. SPSS was used to analyze the data statistically. Paired t test was used for statistical analysis with significance level of 5%.

  Results Top

The noise level measurements at the operator's ear level with minimum and maximum level in dental laboratory, preclinical, and clinical areas before (only turned on) and during dental procedure are shown in [Table 2].
Table 2: Noise level (dB) measured before aTable 2: Noise level (dB) measured before and during procedure in different areas of dental institutionnd during procedure in different areas of dental institution

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In dental laboratory, the highest noise produced during procedure was by the Gypsum lathe trimmer (98.3 dB) and the lowest noise was created by denture polishing (80.62 dB). The noise produced by low-speed air-rotor in preclinics was 69.28 dB. In clinical areas the highest noise produced was by high-speed air-rotor (81.8 dB). The noise created by suction pump when in contact with mucosa was 80.32 dB.

The comparion of the maximum noise level before and during the procedure were made. The significant difference between before and during dental procedure is shown in [Table 2].

  Discussion Top

Noise levels at a given intensity and duration in any environmental situation is a potential health hazard. Since the development of new dental instruments and equipments, the potential for auditory problems has been a concern for the dental profession as well as dental auxiliary's staff. Factors influencing the risk of acoustic trauma are age, physical condition, existing hearing condition of the individual, intensity or loudness of the equipment, length of exposure, and the time between exposures. As a result the dental teaching as well as nonteaching staff is at potential risk of noise-induced hearing loss (NIHL) [5] which intensifies during life. [10] Hence, this study was conducted to find out if the noise levels produced by various dental equipments were within permissible limits.

The results of this study are comparable to the results of other International studies on noise in dental settings. The noise level from high-speed air-rotor in the present study ranged from 73.36 to 81.8 dB. These values are similar to the reports by Mojarad F et al.; [1] (79.6 dB), Kadanakuppe S et al.; [8] (73.4 dB), Singh S et al.; [11] (73. 9 dB to 81.3 dB) and Elmehdi HM [12] (77 dB) However, the noise level in this study was higher as compared to the study reported by Bahannan S, [4] (68 dB) Setcos JC et al.; [5] (72-75 dB) and Sampio Fernandes JC et al.; [7] (69-75 dB).

Dental laboratories in dental institutes are the areas of highest noise levels when compared to other dental learning areas. The noisiest laboratory equipment recorded in this study was Gypsum lathe trimmer, ranging from 87.36 to 98.3 dB followed by Acrylic trimmer (75.42 to 85 dB). This result was in accordance with previous study conducted by Fernandes JC et al.; [7] (93.5 dB) and Kadanakuppe S et al.; [8] (93.1 dB) indicating that gypsum laboratory is the area of highest noise levels due to the frequent use of gypsum vibrator.

The noise created by ultrasonic Scaler was ranged from 63.84 to 74.04 dB. This value was in accordance with the value recorded by Chen Yi-Fen et al.; [13] (70 dB). However, this value was lowered as compared to study conducted by Kadanakuppe S et al.; [8] (83.8 dB) and Singh S et al.; [11] (83 dB).

The suction pump used in the clinical area was affected by the position of the tip. When the tip touched the mucosa, the intensity of noise increased as the soft tissue was caught in the air stream. There was a significant difference (P = 0.01) between the noise level of suction pump when it was used freely and when in contact with mucosa.

In this study, the noise levels generated during cutting were significantly higher (P < 0.05) than those of noncutting, which was proved in the course of the measurements. These demonstrate that the noise level for laboratory metal trimmer during cutting is 83.58 dB, without cutting - 68.3, and, respectively, for the laboratory ceramic trimmer 71.74 and 61.02 dB, low-speed air rotor while cutting acrylic tooth 69.28 and 65.66 dB, and ultrasonic Scaler 74.04 and 65.62 dB. This may be attributed to the friction between the cutting material and cutting tools. [4]

Currently available models have decibel levels equal to or lower than the standards set by the Occupational Safety and Health Act of 90 dB maximum for 8 h of permissible continuous exposure per day (OSHA requires a hearing conservation program for any exposure above an 8 h average of 85 dB). [4] Typically, dentists do not use high-speed air rotor continuously over an 8-h per day. Most are found to use the high-speed air rotor intermittently for 15-30 s. This value may indicate the risk of developing noise induced hearing loss (NIHL) solely from dental drills is minimal. In this study, it was observed that when multiple dental units (high-speed air rotor and ultrasonic scalers) were used the maximum noise levels recorded were 81.8 dB (high-speed handpiece) and 74.04 dB (scalers). These values may be below the maximum permissible value of 85 dB mentioned by OSHA, yet caution should be used to draw the conclusions because these noise levels have a potential to cause damage over a prolonged exposure. The noise level recorded from the dental laboratory was found to exceed the maximum permissible value of 85 dB. This is a matter of concern as it puts the dental technicians at high risk since they spend 6-8 h daily in the dental laboratory. Also, considering the fact that on an average a lecturer would spend at least 1 h in the dental prosthesis laboratory, it can have detrimental effects on the hearing ability over a prolonged period. It is therefore evident that ways and means of reducing the levels of sound in preclinical, clinical and laboratory areas should be given some thought.

NIHL is usually undetected until damage to the inner ear is advanced. There is no treatment for NIHL. On the other side NIHL is an almost wholly preventable condition and adequate preventive measures are also available. It is imperative that a Hearing Conservation Program (HCP) should be instituted in noisy work places. [14] Where regulation do not exist for the need to have a HCP, a protective role must be taken. The elements of an effective HCP include a noise survey, engineering controls, administrative controls, and personal hearing protectors.

Following are the safety standard recommendations for the dental clinic:

  • Handpieces should be adjusted to below 85 dB for 8 h exposure
  • An audiometric test should be taken at the start of employment and every sixth year thereafter, to check up audiograms every 2 years [15]
  • When the noise intensity is above the recommended level, engineering controls should be used to reduce exposure
  • Personal protective equipment should be utilized by individuals exposed to noise above the recommended level and are required for noise exceeding 115 dB
  • Personnel exposed to noise should be informed of hazards, symptoms, and precautions
  • Optimum maintenance procedures should be observed for rotary equipment, including methods of decreasing wear, deterioration, and utilization of concentric burs.

  Conclusion Top

Learning-teaching activities in dental institutions are carried out in a noise polluted environment. Although the sound levels are below that which causes damage to the human ear (85 dB), a necessary reduction of exposure in sound levels is required for acoustic comfort. However, dental technicians and other personnel working all day in noisy laboratories could be at risk of NIHL. The direction should be to prevent occurrence of severe impairment and to retard the development of established injury. The risks of harmful effects must therefore be considered and the preventive and evaluation measures may be undertaken in dental teaching institutions for acoustic comfort.

  References Top

Mojarad F, Massum T, Samavat H. Noise Levels in Dental Offices and Laboratories in Hamedan, Iran. J Dent 2009;6:181-6.  Back to cited text no. 1
Centres for Disease Control (CDC). Leading work-related diseases and injuries-United States. MMWR Morb Mortal Wkly Rep 1983;32:24-6.  Back to cited text no. 2
Millar JD. Screening and monitoring: Tools for prevention. J Occup Med 1986;28:544-6.  Back to cited text no. 3
Bahannan S, el-Hamid AA, Bahnassy A. Noise level of dental hand pieces and laboratory engines. J Prosthet Dent 1993;70:356-60.  Back to cited text no. 4
Setcos JC, Mahyuddin A. Noise levels encountered in dental clinical and laboratory practice. Int J Prosthodont 1998;11:150-7.  Back to cited text no. 5
Leggat PA, Chowanadisai S, Kukiattrakoon B, Yapong B, Kedjarune U. Occupational hygiene practices of dentists in southern Thailand. Int Dent J 2001;51:11-6.  Back to cited text no. 6
Sampio Fernandes JC, Carvalho AP, Gallas M, Vaz P, Matos PA. Noise levels in dental schools. Eur J Dent Educ 2006;10:32-7.  Back to cited text no. 7
Kadanakuppe S, Bhat PK, Jyothi C, Ramegowda C. Assessment of noise levels of the equipments used in the dental teaching institution, Bangalore. Indian J Dent Res 2011;22:424-31.  Back to cited text no. 8
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Chowanadisai S, Kukiattrakoon B, Yapong B, Kedjarune U, Leggat PA. Occupational health problems of dentists in southern Thailand. Int Dent J 2000;50:36-40.  Back to cited text no. 9
Lehto TU, Laurikainen ET, Aitasalo KJ, Pietilä TJ, Helenius HY, Johansson R. Hearing of dentists in the long run: A 15-year follow up study. Community Dent Oral Epidemiol 1989;17:207-11.  Back to cited text no. 10
Singh S, Gambhir RS, Singh G, Sharma S, Kaur A. Noise levels in a dental teaching institute-A matter of concern! J Clin Exp Dent 2012;4:e141-5.  Back to cited text no. 11
Elmehdi HM. Assessing acoustic noise levels in dental clinics and its link to dental anxiety and fear among UAE population. Proceedings of 20 International Congress on Acoustics ICA 2010;1-4.  Back to cited text no. 12
Chen Yi-Fen, Wang Shang-Ru, Chaing Shnag-Peng, Wu Chung-Te, Peng Ying-Ching, Hung Hsing-His, Yu Jen-Fang. The noise of dental instruments evaluated at sound pressure level. Annual Meeting and 22 nd Symposium of Acoustical Society of the Republic of China 2009:54-9.  Back to cited text no. 13
Koh D, Seng CK, J Jeyaratnam. Textbook of occupation medicine practice. 2 nd ed. World Scientific Publishers; 1990. p. 286-312.  Back to cited text no. 14
Other Safety Issues: Eye Protection, Noise Control and Ventilation. Updated from http://www.dentalclinicmanual.com/docs/SafetyIssues.pdf Last accessed on 28 Mar 2014.  Back to cited text no. 15


  [Table 1], [Table 2]

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