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 Table of Contents  
Year : 2021  |  Volume : 11  |  Issue : 3  |  Page : 234-238

Comparative evaluation of three different ultrasonic liquid on microorganisms in dental aerosols

1 PhD Scholar, Department of Periodontology and Implantology, Gujarat University, Ahmedabad, Gujarat, India
2 Department of Periodontology and Implantology, Karnavati University, Gandhinagar, Gujarat, India
3 Department of Restorative Dentistry, Federal University of Pelotas, Pelotas, Brazil

Date of Submission04-Apr-2021
Date of Decision15-May-2021
Date of Acceptance06-Jun-2021
Date of Web Publication04-Sep-2021

Correspondence Address:
Sejal Kathad
Karnavati University, 907/A, Uvarsad, Gandhinagar - 382 422, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/aihb.aihb_57_21

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Introduction: Transmission of diseases has become very common in modern dentistry. This happens mainly due to aerosol production by handpieces and ultrasonic scalers. Aerosol and splatter are terms typically used in dentistry in relation to the microbiological risk of nosocomial transmission. Hence, in order to prevent this, we can use certain chemical agents in the water supply line to prevent the spread of diseases. The objective of this study is to assess the effect of chlorhexidine (CHX) and povidone-iodine (PVI) on the microorganisms in dental aerosols in comparison with distilled water. Materials and Methods: A total of thirty patients were included in this study. They were randomly assigned into three groups of 10 each. Group 1 (Control group): ultrasonic scaling with distilled water, Group 2 (test group): ultrasonic scaling with 2% povidone-iodine, and Group 3 (test group): ultrasonic scaling with 0.12% CHX. Three blood agar plates were kept at a distance of 0.4 m away on either side of the patient and 2 m behind the patient's mouth during ultrasonic scaling. On the patient, ultrasonic scaling is executed for 20 min with a universal tip. Blood agar plates were used to collect the gravitometric settling of dental aerosols, followed by a colony-counting procedure with the help of a microbiologist. Results: The results demonstrated no significant number of colony-forming unit (CFU) were detected at baseline. It is found that Group 3 (CHX gluconate) showed effective CFU reduction (29.2 ± 1.47 CFU) compared to distilled water (126.5 ± 24.02CFU) and povidone-iodine (70.1 ± 2.13 CFU). More CFU was found on blood agar plates which were kept on the right side in all the groups. The results obtained were statistically significant (P < 0.001). Conclusion: CHX is more effective in reducing dental aerosols compared to povidone-iodine, and distilled water in this povidone-iodine is also better than distilled water.

Keywords: Aerosol, chlorhexidine, povidone-iodine, scaling

How to cite this article:
Mehta R, Kathad S, Girdhar G, Bhakkad S, Patel C, Joshi S, Kumar S, Irfan M. Comparative evaluation of three different ultrasonic liquid on microorganisms in dental aerosols. Adv Hum Biol 2021;11:234-8

How to cite this URL:
Mehta R, Kathad S, Girdhar G, Bhakkad S, Patel C, Joshi S, Kumar S, Irfan M. Comparative evaluation of three different ultrasonic liquid on microorganisms in dental aerosols. Adv Hum Biol [serial online] 2021 [cited 2021 Oct 25];11:234-8. Available from: https://www.aihbonline.com/text.asp?2021/11/3/234/325577

  Introduction Top

Transmission of diseases to dental personnel during various procedures has become a source of increased concern to the dental profession.[1] The use of various dental equipment such as high-speed dental handpieces, ultrasonic or sonic scalars, and three-way syringe may generate aerosols and splatters containing microorganisms from the external environment.[2] These aerosols or splatter contain microorganisms which may potentially cause cross-contamination and infect the dental office and affect the health of dental health professionals as well as the patients.[3]

Aerosol and splatter are terms typically used in dentistry in relation to the microbiological risk of nosocomial transmission. In Dentistry, aerosols are defined as a suspension of fine solid or liquid particles in the air having a size <50 μm in diameter. In contrast, splatter is the larger liquid particles in the air having a size of more than 50 μm in diameter.[4],[5] The significant difference between the two is that aerosols are nonballistic, hence remain suspended in the air for longer time periods, whereas splatters are ballistic, therefore they likely to fall on a surface and break apart. This explains why aerosols are linked to more chances of airborne transmission, while splatter leads to contact transmission.[6],[7]

Dental procedures such as the use of high- and low-speed dental handpieces, ultrasonic scalers, air–water syringes, and air abrasion units, which lead to aerosolise viral particles laden saliva from the patient can notably increase chances of disease transmission in dental operatory.[6] So to conclude, a large volume of aerosols produced in the dental operatory along with the SARS-CoV-2 contaminated saliva, irrespective of the patient (symptomatic or carrier), risks the entire dental staff working in the operatory. Hence, it is a must to take both airborne as well as droplet precautions.[8]

Chlorhexidine (CHX) is a proven pre-procedural mouthrinse with its broad-spectrum antimicrobial activity attributed to its bi-cationic inhibitory action, high substantivity and bacterial cell protein chelation.[9] CHX mouthwash led to a reduction of colony-forming unit (CFU) colonies by 94.1% when compared to plain water, which was concluded by Gupta et al.[10] Jawade et al. has demonstrated that CHX is a proven gold standard as a pre-procedural rinse in reducing bacterial aerosol contamination with the use of an ultrasonic scaler. Similarly, povidone-iodine (PVP), when used as a pre-procedural rinse, maintains the diminution of gingival surface microbes throughout the duration of the prophylactic procedure.[11]

Kotsilkov et al. have reported that allergic sensitisation to PVP is unlikely. Only 0.73% of 600 patients displayed a sensitisation reaction in a skin patch test.[12],[13] However, PVP should not be rendered to individuals who are allergic to iodine, suffering from thyroid dysfunction or are pregnant or nursing.[12],[13],[14]

The aim of this study was to evaluate the effect of povidone-iodine and CHX gluconate as an ultrasonic liquid coolant on aerosols in comparison with distilled water.

The objectives were as follows:

  1. To compare the potency of povidone-iodine and CHX gluconate on reducing dental aerosols
  2. Quantitative assessment of microbial content of dental aerosols at right, left and behind the dental chair using three different ultrasonic liquid.

  Materials and Methods Top

This comparative study was conducted on thirty patients of both genders (17 males and 13 females) having an age range of 22–55. The size of the sample was decided after consulting a biostatistician The following formula was used to determine sample size. n = ( Zα/2 + Zβ )2 *2*σ2 / d2 (Where Z α/2 is the critical value of the Normal distribution at α / 2). The subjects for this study were selected from the Outpatient Department of Periodontics, Karnavati School of Dentistry, Gandhinagar, Gujarat, India. The study duration was from July 2019 to October 2019. This study was done under the ethical guidelines of the Institutional Research and Ethical Committee (KU/KSD/2019/208). Participants who met the inclusion criteria were informed about the purpose of the study, and each patient was provided with informed consent after explaining the nature and possible risk.

Inclusion criteria

  • Patients are having a minimum of twenty permanent functional teeth
  • Subjects with mean probing depth ≤5 mm
  • Clinical attachment loss ≤3 mm.

Exclusion criteria

  • Systemic diseases such as diabetes mellitus, hypertension, and rheumatoid arthritis.
  • Use of tobacco in any form
  • History of periodontal treatment in the previous 6 months
  • Pregnant and lactating females
  • Patients with thyroid dysfunction
  • Usage of antibiotic or other drugs
  • Patients allergic to CHX and povidone-iodine were excluded from the study.

Study design

The closed dental operatory was disinfected for 48 h before the procedure to prevent contamination. Patients were assigned to each group by the coin toss method. At the baseline, one blood agar plate was kept for 10 min in the disinfected closed chamber before ultrasonic scaling [Figure 1]. Patients were made comfortable in the dental chair. Three blood agar plates were kept at a distance of 0.4 m away on either side of the patient and 2 m behind the patient's mouth during ultrasonic scaling[8] [Figure 1]. The patients ultrasonic scaling was executed for 20 min by the clinician, with a universal tip attached to the ultrasonic scaler. The normal rate of flow of water in ultrasonic scaler is 20–30 ml/min. The same rate of flow of water for each agent while performing ultrasonic scaling was maintained. To ensure that the room was free from aerosols, only one patient was treated per day. For every scaling procedure, high vacuum suction was used. After the treatment, three coded blood agar plates were left uncovered for 20 min at the pre-designated sites for gravimetric settling of airborne bacteria. After gravimetric settling of aerosols, blood agar plates were transferred to the laboratory for incubation at 37°C for 48 h [Figure 2], followed by a colony-counting procedure with the help of a colony counter device by the microbiologist. All the patients were treated by a single operator to prevent the inter-operator bias.
Figure 1: Position of blood agar plate.

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Figure 2: Blood agar plates at right, left and behind patient's mouth, respectively, in Group 1, 2 and 3.

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Statistical analysis

For determination of overall inference, one way-ANOVA test was performed. Tukey's Post hoc test was applied for analysing intergroup comparison of CFU.

  Results Top

In this study, thirty patients were selected and were randomly divided into distilled water, povidone-iodine and CHX groups; each group consisted of ten subjects. The clinical parameters were recorded to confirm the diagnosis of chronic periodontitis.

The mean colony counts on all sides in Group 1, Group 2 and Group 3 were compared in [Table 1]. This indicates that Group 3 (CHX gluconate) had effective CFU reduction (29.2 ± 1.47CFU) when compared to distilled water (126.8 ± 24.02CFU) and povidone-iodine (70.1 ± 2.13 CFU). On applying one-way ANOVA test, the 'F' ratio obtained was 123.4 with a P = 0.001, which was statistically significant. These results can be attributed to the antiseptic and antimicrobial properties of CHX. The comparison of mean CFU on the right side (156.2 ± 10.7, 123.4±5.56 and 43.2 ± 1.87), left side (124.3 ± 8.3, 61.8 ± 2.9, 29.9 ± 3.1) and back side (80.2 ± 2.6,24.9 ± 3.2,14.1 ± 2.42) of the patient in Group 1, Group 2 and Group 3 respectively, showed statistically significant (P = 0.001) results as demonstrated in [Table 2], [Table 3], [Table 4].
Table 1: Comparison of mean colony count on all sides amongst different groups

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Table 2: Comparison of mean colony count on right side amongst different groups

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Table 3: Comparison of mean colony count on left side amongst different groups

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Table 4: Comparison of mean colony count on back side among different groups

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  Discussion Top

Gingivitis and periodontitis are associated with local factors of plaque and calculus and the response of the host against them.[15] Systemic conditions such as diabetes, smoking habit and the presence of other chronic diseases also play a part in the development of periodontal diseases.[16] However, scaling and root planning forms the cornerstone and is the primary treatment for the majority of cases of gingivitis and periodontitis.[17] Various mechanical methods for the removal of plaque and calculus is employed, which includes hand scaling, ultrasonic scaling or root planning by hand instruments.

Every profession carries with it the risk of professional hazards. In dentistry, neck and back pain related to posture is one of the hazards.[18] Another issue is the exposure of the dentist and the dental staff to the chemicals and toxic gases or vapours in the clinic.

Multiple methods have been devised for the protection of the dentists and the staff to overcome the issue of airborne and blood-borne infections and pathogens. This includes practising the principle of 'universal precautions', use of barrier methods, using high power suction, pre-procedural rinse, air filters in the operatory and using ultraviolet lights.[19]

The effectiveness of pre-procedural rinsing is proven in many studies.[20] While performing ultrasonic scaling, the depth of the periodontal pockets and the length of the scaler tip is between 4 and 7 mm.[21] The antibacterial effects of pre-procedural rinsing does not extend to these depths. Thus, there is an adjunctive need for the use of an antimicrobial chemical agent to minimise the actual production of the contaminated aerosol generated.

CHX digluconate 0.12% has been used extensively in the dental and medical profession for a long time. In dentistry, it is used in the cases of gingivitis and periodontitis as an adjunct to scaling and root planing. CHX has an antimicrobial property that is attributed to its action on the inner cytoplasmic membrane. Due to its broad-spectrum antimicrobial activity and good substantivity, it is recommended as a gold standard for plaque control.[22]

Elemental iodine and its derivatives are highly potent and have a broad spectrum of antiseptic action.[23] Diluted PVP-iodine is capable of killing Aggregatibacter Actinomycetemcomitans, Porphyromonas gingivalis and other periodontal pathogens with as little as 15 s of contact.[24] PVP-iodine also effective against herpes virus and yeasts.[24] However, herpes virus shows resistance to CHX.

In this study, its growth of CFU on all the agar plates placed at different sides and with different distances was observed. This suggests that a sufficient amount of aerosol was generated at all times during ultrasonic scaling procedures. It has been observed that the microorganisms spreading through aerosol mode mostly travel towards the patient's chest and the right side of the patient. A similar result was seen in this study where the colony count was higher for the right side of the patient as compared to the left or the backside while using any type of coolant [Table 3].

CHX and povidone-iodine coolant were effective in reducing the number of bacteria in all three locations studied, as compared to the distilled water [Table 2]. CHX showed a better reduction in CFU growth as compared to povidone-iodine [Table 5]. The reason behind the better efficacy of CHX as compared to povidone-iodine could be due to its faster action, not reduction in efficacy even after exposure to bodily fluids and due to its substantivity (residual effect). Similar results were seen in the study done by Vandana et al.[25] and Jawade et al.[11]
Table 5: Comparison of mean colony count on all sides among different groups by Tukey's post hoc test

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Some patients may report an unpleasant taste of the solutions. However, this use is for a short duration of scaling appointment only, and it is not advised for daily use.

The dental team should use a multipronged approach for the reduction and containment of dental aerosol production. Face masks, gloves, head cap and eye goggles are the first line of defence. The second layer consists of pre-procedural mouth rinse and the use of high-volume evacuation. Based on this study, the addition of CHX or povidone-iodine to water coolant in ultrasonic scaler should also be routinely employed by the periodontists as it is inexpensive and effective.

  Conclusion Top

This study indicates that CHX gluconate as an ultrasonic liquid coolant significantly reduces the microbial content of dental aerosols generated during scaling when compared with distilled water. CHX gluconate showed better CFU reductions when compared with povidone-iodine. Povidone-iodine also showed better CFU reduction when compared with distilled water. Hence, povidone-iodine can also be used as an ultrasonic liquid coolant for reducing the number of dental aerosols during ultrasonic scaling.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Volgenant CM, de Soet JJ. Cross-transmission in the dental office: Does this make you ill? Curr Oral Health Rep 2018;5:221-8.  Back to cited text no. 1
Sethi KS, Mamajiwala A, Mahale S, Raut CP, Karde P. Comparative evaluation of the chlorhexidine and cinnamon extract as ultrasonic coolant for reduction of bacterial load in dental aerosols. J Indian Soc Periodontol 2019;23:226-33.  Back to cited text no. 2
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Nulty A, Lefkaditis C, Zachrisson P, Van Tonder Q, Yar R. A clinical study measuring dental aerosols with and without a high-volume extraction device. Br Dent J. 2020 Nov 20;1-8. doi: 10.1038/s41415-020-2274-3.  Back to cited text no. 3
Izzetti R, Nisi M, Gabriele M, Graziani F. COVID-19 transmission in dental practice: Brief review of preventive measures in Italy. J Dent Res 2020;99:1030-8.  Back to cited text no. 4
Miller RL, Micik RE, Abel C, Ryge G. Studies on dental aerobiology. II. Microbial splatter discharged from the oral cavity of dental patients. J Dent Res 1971;50:621-5.  Back to cited text no. 5
Harrel SK, Molinari J. Aerosols and splatter in dentistry: A brief review of the literature and infection control implications. J Am Dent Assoc 1939 2004;135:429-37.  Back to cited text no. 6
Micik RE, Miller RL, Mazzarella MA, Ryge G. Studies on dental aerobiology. I. Bacterial aerosols generated during dental procedures. J Dent Res 1969;48:49-56.  Back to cited text no. 7
Jamal M, Shah M, Almarzooqi SH, Aber H, Khawaja S, El Abed R, et al. Overview of transnational recommendations for COVID-19 transmission control in dental care settings. Oral Dis. 2021;27:655–64.   Back to cited text no. 8
Feres M, Figueiredo LC, Faveri M, Stewart B, de Vizio W. The effectiveness of a preprocedural mouthrinse containing cetylpyridinium chloride in reducing bacteria in the dental office. J Am Dent Assoc 2010;141:415-22.  Back to cited text no. 9
Gupta G, Mitra D, Ashok KP, Gupta A, Soni S, Ahmed S, et al. Efficacy of preprocedural mouth rinsing in reducing aerosol contamination produced by ultrasonic scaler: A pilot study. J Periodontol 2014;85:562-8.  Back to cited text no. 10
Jawade R, Bhandari V, Ugale G, Taru S, Khaparde S, Kulkarni A, et al. Comparative evaluation of two different ultrasonic liquid coolants on dental aerosols. J Clin Diagn Res 2016;10:ZC53-7.  Back to cited text no. 11
Kotsilkov K, Emilov D, Popova C. Subgingival irrigations with povidone-iodine as adjunctive treatment of chronic periodontitis. J IMAB Annu Proc Sci Pap 2010;15:84-8.  Back to cited text no. 12
Research, Science, and Therapy Committee. Informational paper: Modulation of the Host response in periodontal therapy. J Periodontol 2002;73:460-70.  Back to cited text no. 13
Kanagalingam J, Feliciano R, Hah JH, Labib H, Le TA, Lin J-C. Practical use of povidone-iodine antiseptic in the maintenance of oral health and in the prevention and treatment of common oropharyngeal infections. Int J Clin Pract 2015 Nov;69:1247-56.  Back to cited text no. 14
Murakami S, Mealey BL, Mariotti A, Chapple IL. Dental plaque-induced gingival conditions. J Periodontol 2018;89 Suppl 1:S17-27.  Back to cited text no. 15
Nazir MA. Prevalence of periodontal disease, its association with systemic diseases and prevention. Int J Health Sci (Qassim) 2017;11:72-80.  Back to cited text no. 16
Tariq M, Iqbal Z, Ali J, Baboota S, Talegaonkar S, Ahmad Z, et al. Treatment modalities and evaluation models for periodontitis. Int J Pharm Investig 2012;2:106-22.  Back to cited text no. 17
Ayatollahi J, Ayatollahi F, Ardekani AM, Bahrololoomi R, Ayatollahi J, Ayatollahi A, et al. Occupational hazards to dental staff. Dent Res J 2012;9:2-7.  Back to cited text no. 18
Yang M, Chaghtai A, Melendez M, Hasson H, Whitaker E, Badi M, et al. Mitigating saliva aerosol contamination in a dental school clinic. BMC Oral Health 2021;21:52.  Back to cited text no. 19
Marui VC, Souto ML, Rovai ES, Romito GA, Chambrone L, Pannuti CM. Efficacy of preprocedural mouthrinses in the reduction of microorganisms in aerosol: A systematic review. J Am Dent Assoc 1939 2019;150:1015-26.e1.  Back to cited text no. 20
Balejo RD, Cortelli JR, Costa FO, Cyrino RM, Aquino DR, Cogo-Müller K, et al. Effects of chlorhexidine preprocedural rinse on bacteremia in periodontal patients: A randomized clinical trial. J Appl Oral Sci 2017;25:586-95.  Back to cited text no. 21
Thangavelu A, Kaspar SS, Kathirvelu RP, Srinivasan B, Srinivasan S, Sundram R. Chlorhexidine: An elixir for periodontics. J Pharm Bioallied Sci 2020;12 Suppl 1:S57-9.  Back to cited text no. 22
Eggers M. Infectious disease management and control with povidone iodine. Infect Dis Ther 2019;8:581-93.  Back to cited text no. 23
Kanagalingam J, Feliciano R, Hah JH, Labib H, Le TA, Lin JC. Practical use of povidone-iodine antiseptic in the maintenance of oral health and in the prevention and treatment of common oropharyngeal infections. Int J Clin Pract 2015;69:1247-56.  Back to cited text no. 24
Vandana K, Desai R, Kaur R, Singh I. Effect of chlorhexidine, povidone iodine, and ozone on microorganisms in dental aerosols: Randomized double-blind clinical trial. Indian J Dent Res 2014;25:160.  Back to cited text no. 25
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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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