Indian Journal of Oral Health and Research

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 5  |  Issue : 1  |  Page : 11--16

Sound levels in conservative dentistry and endodontics clinic


Sumita Bhagwat, Pradnya Hirlekar, Leena Padhye 
 Department of Conservative Dentistry and Endodontics, DYPU School of Dentistry, Navi Mumbai, Maharashtra, India

Correspondence Address:
Dr. Sumita Bhagwat
Department of Conservative Dentistry and Endodontics, DYPU School of Dentistry, Navi Mumbai, Maharashtra
India

Abstract

Aim: The aim of this study was to evaluate the sound levels generated in dental clinics of Conservative Dentistry and Endodontics. Materials and Methods: A decibel-meter with digital readout was used to measure sound levels at different intervals at chairside and center of preclinical laboratory and undergraduate and postgraduate clinics. At chairside, recordings were made with the meter held near the operator's ear when only suction was being used, with the slow speed micromotor handpiece and while suction was used alongside the air rotor handpiece. The recordings at the center of the clinic were made with at least five operators working. Minimum and maximum readings during a 3 min interval were recorded. Results: The tabulated readings were statistically analysed by ANOVA and Tukey HSD comparison test. Conclusion: The authors concluded that the mean sound levels in the working clinics ranged from 54 dB[A] to 83.3 dB[A]. These were within the recommended range for dental equipment. With suction and high speed handpiece combination, the Postgraduate clinic was significantly noisier than the Undergraduate clinic at several time periods. Sound level measurements reported here raise some concerns for dentists' hearing health. The use of suction with and without accompanying handpiece use can produce noise sufficient to damage the user's hearing.



How to cite this article:
Bhagwat S, Hirlekar P, Padhye L. Sound levels in conservative dentistry and endodontics clinic.Indian J Oral Health Res 2019;5:11-16


How to cite this URL:
Bhagwat S, Hirlekar P, Padhye L. Sound levels in conservative dentistry and endodontics clinic. Indian J Oral Health Res [serial online] 2019 [cited 2019 Sep 23 ];5:11-16
Available from: http://www.ijohr.org/text.asp?2019/5/1/11/261152


Full Text



 Introduction



For the past 25 years, dental professionals have become increasingly aware of the number of occupational hazards associated with working in a dental office. We protect our skin with gloves and laboratory jackets, our eyes with protective eyewear, our noses and mouths with masks and face shields, and our neck, shoulder, and back postures with loupes and saddle stools. However, most dental health-care workers do not take an active role in protecting their hearing in the workplace.

When it comes to noise, the dental office is a polluted environment. Dental health-care workers are constantly subjected to both intermittent and continuous noise from high-speed handpieces, ultrasonic scalers, suction devices, automated mixers, ultrasonic instrument cleaners, instrument washers, vacuum pumps, air compressors, model trimmers, business office equipment, telephones, entertainment systems, and heating and air-conditioning units.

Due to infection control concerns, today's dental offices are designed with hard surfaces that are easy to clean. However instead of absorbing sound well, hard surfaces radiate sounds throughout the office.

In an attempt to reduce workers' risk of developing noise-induced hearing loss (NIHL), the United States Occupational Safety and Health Administration established safety standards related to noise exposure.[1] Originally published in 1983, the standard states that the maximum permissible exposure limit in an 8-h day should not exceed 90 dBA sound pressure level (SPL). However, there is neither such safety standard established for Indian dental clinicians nor is occupational safety with regard to hearing loss given any significant importance or priority.

The lacunae in attention and concern for Indian dental professionals affected by NIHL motivated us to carry out a study in our dental clinics for measurements of sound levels and make recommendations from the results obtained.

Aims and objectives

The aim of our study was to measure, analyze, and compare noise levels of equipment among dental learning areas under different working conditions.

Objectives

To measure noise levels produced by various dental equipment in the student clinicsTo estimate the risk of tinnitus and NIHL in practicing dentists by determining whether the noise levels exceed current guidelines for occupational noise levelsTo recommend improvements if noise levels are not within permissible limits.

 Materials and Methods



A decibel meter (Sound Level Meter; Lutron SL-4011, 30-130 dB, Australia) was used for recording sound levels in the preclinical laboratory, undergraduate, and postgraduate clinics of the Department of Conservative Dentistry and Endodontics at 8.30 am, 9.30 am, 11.30 am, and 3.30 pm. At each of these time periods, the meter was activated for an interval of 3 min, and the minimum and maximum values were recorded and noted in a tabular format. The recordings were made at the chairside and center of the clinic during the normal functioning of the clinic. At chairside, recordings were made with the meter held near the operator's ear (6 inches away from the operator's ear) while only the suction was being used, with the slow-speed micromotor handpiece and while suction was used alongside the air rotor handpiece. The recordings at the center of the clinic were made with at least five operators working. All the equipment that was used for the clinical procedures was in good working condition. The burs and diamond points used in the handpieces were those used by the operators during normal clinical practice. The pressure for compressed air in the dental chair was set at the maximum permissible values as designated by the manufacturers while being compatible with the values prescribed for the respective handpieces (pressure 6 kg/cm2). The postgraduate clinic was air conditioned, whereas the undergraduate clinic was non air conditioned but had good ventilation. None of the clinical areas were carpeted, and the windows did not have curtains.

The mean of the minimum recordings and the maximum recordings was calculated for each set of the equipment at the chairside and at the center of the clinic for both clinics and at different times. Differences in intragroup measurements of sound between various equipment were analyzed using the ANOVA test and the Tukey's honestly significant difference (HSD) test. Intragroup measurements comparing differences between various times were analyzed using the ANOVA test. Comparisons between the postgraduate and undergraduate clinics were made with the independent t-test. The levels of significance were set at P < 0.05.

 Discussion



Hearing problems are a classic outcome of aging. Over time, the sounds a person hears become muffled or distorted. A classic symptom of NIHL is difficulty in understanding everyday conversations. Other indicators of a hearing problem include:

Trouble hearing a phone conversationDifficulty in following a conversation with two or more people or straining to hear what is being saidTrouble hearing when there is background noiseAsking people to repeat themselvesThinking people are mumbling or not speaking clearlyMisunderstanding what others are saying, or turning up the radio or TV volume too high.

Symptoms of NIHL increase gradually over time and the person may not be aware of the loss, which can be confirmed with a hearing test. NIHL is cumulative, invisible, and permanent. Unlike industrial workers who are covered by occupational noise regulations, medical professionals are not regulated by any governmental agency. Although the FDA has not imposed any noise regulations, published studies reviewed below show that certain medical professionals are exposed to hazardous levels of noise in the workplace. Literature concludes that these levels could indeed cause a temporary and/or permanent threshold shift.[1] Not only are surgeons of multiple specialties exposed to levels of noise that can cause hearing loss but also dental professionals are as well. Studies published as early as 1959 suggested that the use of high-speed ball-bearing turbines in dental practices can cause hearing loss.[1]

In our study, the decibel levels reading noted at chairside and center of undergraduate clinic at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) with suction and airotor on were compared [Table 1]. The maximum and minimum readings recorded at chairside were 86.6 dB (A) and 76.7 dB (A) and at the center of clinic were 76.2 dB (A) and 61.8 dB (A), respectively [Graph 1]. There was statistically significant difference at all times when comparing center of the clinic with chairside when both suction and airotor were on in the undergraduate clinic [Table 2].{Table 1}{Table 2}[INLINE:1]

In similar study models, the study by Dutta et al.[2] showed that the difference in noise levels between the center of the clinic and the chairside with suction and airotor handpiece was very highly significant for both minimum and maximum values (P = 0.001), and the study bfy Al-Dujaili et al.[3] stated that there was statistically significant difference observed during both background and activity measurements. The findings of both studies are in agreement with our findings.

In this study, the decibel levels reading noted at chairside and center of postgraduate clinic at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) with only suction on were compared [Table 3]. The maximum and minimum readings recorded at chairside were 78.8 dB (A) and 73.9 dB (A) and at the center of clinic were 83.3 dB (A) and 54 dB (A), respectively [Graph 2]. There is a statistically significant difference between chairside and center of clinic at 8.30 am as compared to all other times when only suction is on in the postgraduate clinic [Table 4].{Table 3}{Table 4}[INLINE:2]

In similar study models, the study by Dutta et al.[2] stated that there were no differences existed between the center and the chairside when suction was used alone. These findings were not in agreement with those of our study. Kadanakupp et al.[4] stated that the suction pump used in the clinical area was affected by the position of the tip. When the tip of the suction touched the mucosa, the intensity of noise increased as the soft tissue was caught in the air stream. Sorainen and Rytkönen[5] found that during the simulated work, the average A-weighted SPL of the power suction tube was 77 dB (A) and the saliva suction tube 75 dB (A) which indicates that dentists have higher hearing thresholds than expected. The findings of all the studies are in agreement with our findings.

In this study, the decibel level reading noted at chairside and center of postgraduate clinic at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) with suction and airotor on was compared [Table 5]. The maximum and minimum readings recorded at chairside were 85.3 dB (A) and 77.8 dB (A) and at the center of clinic were 83.3 dB (A) and 54 dB (A), respectively [Graph 3]. There was statistically significant difference at all times when comparing chair-side with center of clinic when both suction and airotor were on in the postgraduate clinic [Table 6].{Table 5}{Table 6}[INLINE:3]

In similar study models, the study by Dutta et al.[2] showed that the difference in noise levels between the center of the clinic and the chair-side with suction and airotor handpiece was very highly significant for all the maximum readings (P = 0.001). Al-Dujaili et al.[3] in his study recorded sound data and summarized that there were significant differences observed during both background and activity measurements. Using suction and drilling resulted in significantly high noise levels than talking with patients or undertaking other activities. The findings of all the studies are in agreement with our findings.

In our study, the decibel levels reading taken at chairside of postgraduate clinic and undergraduate clinic at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) with suction and airotor on were compared [Table 7]. The maximum and minimum readings recorded at chairside were 85.3 dB (A) and 77.8 dB (A) in the postgraduate clinic, and the maximum and minimum readings recorded at chairside were 86.6 dB (A) and 76.7 dB (A) in the undergraduate clinic [Graph 4]. There exists no significance of difference between the undergraduate and postgraduate clinics when both airotor with suction was on (P > 0.05) at all-time points [Table 8].{Table 7}{Table 8}[INLINE:4]

In similar study models, the study by Dutta et al.[2] showed that for readings of suction with airotor handpiece, the difference between the undergraduate and postgraduate clinics varied significantly for all maximum readings at 9.30 am (P = 0.008), 11.30 am (P = 0.001), and 3.30 pm (P = 0.02) but for minimum readings at only 9.30 am (P = 0.007). (f) During drilling, the average ultrasound levels of the handpieces were below 90 dB in all one-third octave bands of 20,000–80,000 Hz. This is close to the American Conference of Governmental Industrial Hygienist's limit value of 110 dB as per the study done by Sorainen and Rytkönen[5] and similar to our study.

The decibel levels were compared for readings taken at the center of undergraduate, postgraduate, and preclinics at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) at baseline and activity recordings [Table 9]. The maximum and the minimum readings of the center of undergraduate clinic were 76.2 dB (A) and 61.8 dB (A); the center of the postgraduate clinic was 83.3 dB (A) and 54 dB (A) and the center of the preclinics was 75.2 dB (A) and 71.9 dB (A), respectively [Graph 5]. There was no statistical significance of difference when we compared center of undergraduate, postgraduate, and preclinical areas at any time in the department (P > 0.05) [Table 10].{Table 9}{Table 10}[INLINE:5]

In similar study models, comparison between the undergraduate and postgraduate clinics showed no difference in noise levels at baseline measurements 8.30 am and neither for readings at 11.30 am or minimum readings at 3.30 pm in a study done by Dutta et al.[2] Ward and Holmberg[6] suggested that drill noise could not possibly affect frequencies below 3 KHz. Only 2, 3, 4, 6, and 8 KHz were checked in their study. The noise exposure pattern to which the dentist is exposed varies widely from day to day and depends on the nature of the practice. According to the study by Altinöz et al.,[7] there was no statistically significant difference in the frequencies recorded under different working conditions, in agreement with our findings.

The decibel levels were compared for readings taken at the chairside of preclinics, undergraduate, and postgraduate clinics at four different times (8.30 am, 9.30 am, 11.30 am, and 1.30 pm) with micromotor handpiece on in preclinics, airotor on in undergraduate clinic, and only suction on in postgraduate were compared [Table 11]. The maximum and minimum readings of micromotor were 77.50 and 75.10 dB (A), of airotor were 85.90 and 77.80 dB (A), and of suction were 85.30 and 77.80 dB (A), respectively [Graph 6]. P value for the ANOVA test showed statistical significance of difference when we compared micromotor against undergraduate only airotor against postgraduate suction, and the Tukey's HSD comparison test shows that there was statistical significance of difference when we compared micromotor against only airotor and only suction on, but there was no statistical difference when only airotor was compared against only suction on [Table 12] and [Table 13].{Table 11}{Table 12}{Table 13}[INLINE:6]

In similar study models, a study by Dutta et al.[2] showed no statistical difference at the chairside in noise generated by suction alone, suction with the micromotor, or suction with airotor. Another study by Altinöz et al.[7] indicated that under any working conditions (under free working conditions without burs, with fissure burs, with flare burs, with round burs, and with inverted cone burs), high-speed dental air turbines emit noise at frequencies that may cause hearing loss over time. Kadanakuppe et al.[4] stated in his study that the high-speed turbine was the noisiest equipment compared to low-speed contra-angle and straight handpieces. In a study by Qsaibati et al.,[8] the high-speed turbine was the noisiest equipment compared to low-speed contra-angle. This agrees with the findings of Bahannan et al.,[9] Altinöz et al.,[7] and Fernandes et al.[10] This is concordant with antecedent studies mentioning that the high-speed turbine handpiece generates a higher noise level than the low-speed handpiece. Maximum SPLs of the noise created by the dental drill were 91.9 dB by the brand used dental turbine while cutting on a tooth, which has a risk of damage to the dentists' hearing.

 Conclusion



In this study, the mean sound levels in the working clinic were recorded in a range of:

Minimum – 54 dB (A)

Maximum – 83.3 dB (A)

The postgraduate clinic had higher sound levels as compared to the undergraduate clinic. With suction and high-speed handpiece combination, the postgraduate clinic was significantly noisier than the undergraduate clinic at several time periodsDifferences existed between equipment combinations at different times of the day when the postgraduate and undergraduate clinics were compared. However, the equipment combinations at chairside in either clinic did not differ the noise levels with time in the working clinic.

Although the sound levels are below the current guidelines for occupational noise levels (85 dB [A]) which cause risk of tinnitus and NIHL, a necessary reduction of exposure in sound levels is required for acoustic comfort. Reducing the sound level of noise sources (by 4–7 dB [A]) can be obtained by regular maintenance and early repairs of handpieces, replacement of defective items, and use of newer less noisier models or by increasing the sound absorption of the room (where a decrease of 3–5 dB [A] is possible). By these measures, it would be possible to reduce the noise levels by 7–12 dB (A) and thus achieving a minimum level of comfort for these work areas.

Sense of hearing is of immeasurable worth and deserving of our most vigilant efforts to preserve and protect it. Just as the dental team gears for meeting infection control requirements, it should similarly enforce a hearing conservation program and aim at prevention of NIHL in dental clinicians and clinical assistants alike.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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