Care or neglect of burs: A comparative study of different sterilization methods

HR Pooja; Priya Nagar; Andrea Natalia Mascarenhas; C H. Chandana Krishna Shree

doi:10.4103/srmjrds.srmjrds_22_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 13 | Issue : 2 | Page : 54-57

Care or neglect of burs: A comparative study of different sterilization methods

HR Pooja, Priya Nagar, Andrea Natalia Mascarenhas, C H. Chandana Krishna Shree
Department of Pediatric and Preventive Dentistry, Krishnadevaraya College of Dental Sciences, Bengaluru, Karnataka, India

Date of Submission	04-Feb-2022
Date of Decision	05-May-2022
Date of Acceptance	07-May-2022
Date of Web Publication	20-Jun-2022

Correspondence Address:
Dr. H R Pooja
Department of Pediatric and Preventive Dentistry, Krishnadevaraya College of Dental Sciences, Hunsamaranahalli, International Airport Road, Bengaluru - 562 157, Karnataka
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/srmjrds.srmjrds_22_22

Abstract

Background: Burs are unique by virtue of their complex architecture which makes precleaning and sterilization difficult to achieve. Inadequate sterilization causes cross infection. Aim: The aim of the present study was to assess and compare the effectiveness of various sterilization methods of dental diamond burs commonly utilised in dental practice. Methodology: The current study was done to investigate the efficacy of four decontamination methods on fifty diamond burs. These burs were used among ten patients who were indicated for pulp therapy in primary deciduous molars. Access cavity preparation was prepared using dental burs and divided into five groups: Group I - being control group (unsterilized), Group II - Contaminated burs sterilized using 2% glutaraldehyde, Group III -Contaminated burs sterilized in autoclave, Group IV - Contaminated burs sterilized in ultraviolet steriliser, and Group V - Contaminated burs sterilized using 70% isopropyl alcohol. All the burs were immersed in the Brain − Heart Infusion broth, incubated for 24 h at 37°C to check the sterility of burs. Bacterial culture (Broth turbidity) was then measured for its optical density (OD) using the spectrophotometer. OD values reading were recorded and statistical analysis was done using Kruskal–Wallis test and Mann–Whitney's post hoc TEST. Results: Among all decontamination methods, 2% glutaraldehyde and autoclave showed the most significant change in microbial load compared to the other group at P < 0.001. Conclusion: Sterilization with 2% glutaraldehyde followed by autoclave of dental burs is the key step in achieving success in the endodontic procedures with less microbial load which determines the success of pulpectomy procedures.

Keywords: Dental burs, glutaraldehyde, optical density, spectrophotometer, ultraviolet sterilizer

How to cite this article:
Pooja H R, Nagar P, Mascarenhas AN, Krishna Shree C H. Care or neglect of burs: A comparative study of different sterilization methods. SRM J Res Dent Sci 2022;13:54-7

How to cite this URL:
Pooja H R, Nagar P, Mascarenhas AN, Krishna Shree C H. Care or neglect of burs: A comparative study of different sterilization methods. SRM J Res Dent Sci [serial online] 2022 [cited 2023 Mar 31];13:54-7. Available from: https://www.srmjrds.in/text.asp?2022/13/2/54/347812

Introduction

Infection control is one of the booming spheres in dentistry. In our day-to-day practice in dental set up, dentists reuse the instruments on multiple number of patients after sterilization. If adequate sterilization is not done, it can pose a risk of transmitting disease, not only to patients but also to the dental staffs, clinicians and the parents or guardians accompanying child patient during the course of treatment.^[1]

The principal method of sterilization of dental burs includes steam sterilizer, glass bead sterilizer, chemical disinfectants, hot air oven, surgical spirit, and more recently ultraviolet (UV) is also being used. Autoclave is the most commonly used wherein the combination of pressure of about 15 lbs, steam and a high temperature of about 121°C in the chamber for a longer period of time can destroy all microorganisms as well as spores effectively.^[2] UV rays are one of the potent methods and have been acknowledged for killing microbes without any use of cold sterilizer and heat during the procedure. The principle behind UV sterilizer is when the UV rays has been passed through any substance at particular wavelength, microorganisms cannot multiply.^[3] Applying certain chemicals and use of alcohol are other two widely used methods for disinfecting the dental burs. Antimicrobial properties of alcohol aid in disinfection of dental instruments. In the healthcare setup, alcohol is composed of major constituents such as isopropyl alcohol and ethanol which is bactericidal. They also provide other advantages such as tuberculocidal, fungicidal, and virucidal actions.^[4] Glutaraldehyde, a chemosterilizer acts like an antibiotic in providing a broad spectrum of action, thereby inhibiting the growth of microbes including bacterial spores, fungal spores, protozoans, viruses, etc.

Dentistry is one of the professions which exposes the dentist, dental staff, and the patient to various respiratory diseases, for example, COVID-19.^[5] Maximum of it through aerosols from the airotor and by various dental instruments including dental burs which are salvageable. Instruments are reused and majority of dentists practices the same worldwide and is also accepted by many administrative communities such as American Dental Association. Dental burs are sterilized and reused in dental practices for various procedures, but still only limited number of studies report the accurate method of sterilization of dental burs.^[6]

Thus, the aim of the present study was to assess and estimate the effectiveness of various decontamination processes of dental burs commonly used in dentistry.

Methodology

The study was conducted after obtaining approval from the institutional ethical committee. All the participants provided written informed consent for the participation in the study. All procedures performed in the study were conducted in accordance with the ethical standards given in 1964 Declaration of Helsinki, as revised in 2013. The sample size was estimated using the GPower software v. 3.1.9.4 (Franz Faul, Universität Kiel, Germany). Fifty diamond dental round burs (size no. 18) used in ten different patients who underwent pulp therapy were grouped randomly into five groups, ten in each group.

Group I: Control group (unsterilized)
Group II: Contaminated burs sterilized using 2% glutaraldehyde.
Group III: Contaminated burs sterilized in autoclave
Group IV: Contaminated burs sterilized in UV sterilizer
Group V: Contaminated burs sterilized using70% isopropyl alcohol.

Five burs were used in each patient for access cavity preparation. After the initial punch cut with one bur, the remaining four burs were used on each wall of the cavity for 30 s. One set of burs was directly transferred to Eppendorf tube containing Brain − Heart Infusion (BHI) broth without any decontamination procedure done for it and were referred to as Group I as controls.

Other four burs will be subjected to four different decontamination methods like:

Group II-contaminated burs was immersed in 2% glutaraldehyde for 15 min
Group III-contaminated burs was sterilized by autoclaving at 121°C, 15 lbs for 15 min
Group IV-contaminated burs was sterilized in UV sterilizer for 15 min
Group V-Contaminated burs was sterilized by immersing the burs in 70% isopropyl alcohol for 15 min

After sterilization, all the four burs were transferred to Eppendorf tube containing BHI broth. The tubes were incubated at 37°C for 24 h. Broth turbidity [Figure 1] was evaluated by measuring the optical density (OD) using Spectrophotometer, in the Microbiology laboratory, Krishnadevaraya College of Dental Sciences, Bengaluru, India. The comparison of mean OD values between groups using Kruskal–Wallis test and multiple comparison of mean difference in OD values between the groups using Mann–Whitney's post hoc test [Table 1] and [Table 2]. P < 0.001 was considered to be significant.

Figure 1: BHI broth showing increased turbidity indicating microbial load even after sterilisation dental burs in UV steriliser. BHI: Brain Heart Infusion, UV: Ultraviolet

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Table 1: Comparison of mean optical density values between groups using Kruskal–Wallis test

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Table 2: Multiple comparison of mean difference between different groups

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Results

Among all decontamination methods, Group II and Group III (2% glutaraldehyde and Autoclave) showed the most significant change in microbial load compared to the other groups. The test results showed the mean OD of microbial load for control group was 1.3428 ± 0.4093, glutaraldehyde group was 0.0626 ± 0.0487, autoclave group was 0.0067 ± 0.0041, UV group was 0.8385 ± 0.1775 and ethanol group was 0.1497 ± 0.2683. There was a significant difference observed in the mean OD of microbial load between five groups at P < 0.001 [Table 1].

Multiple comparison of the mean difference between groups showed that the autoclave group had significantly least OD of microbial load in comparison with remaining study groups and control groups at P < 0.001. Then, it was followed by both glutaraldehyde and ethanol groups which showed significantly lesser OD values as compared to UV and control groups at P < 0.001. This was later observed next with UV group showing significantly lesser OD values with respect to the control group at P < 0.001. However, the mean OD values between glutaraldehyde and ethanol groups (P = 0.41) had no statistical significant difference observed [Table 2].

Discussion

Oral cavity is the residence to an enormous number of microorganisms. Dental treatments could aid in cross infection during the procedure. Various types of endodontic instruments are available according to the requirements of the clinician. The instruments are broadly classified according to their nature as disposable and reusable instruments based on sterilization processes. Dental bur is one of the reusable instruments which can be reused after proper sterilisation.

Dental burs are one such miniature instrument commonly put-to-use in dentistry for different types of procedures, which includes excavation of caries, crown reduction, access cavity preparation, osteoplasty, etc. Dental burs become deliberately contaminated with saliva, blood, necrotic tissue, and pathogens like microbes during the procedures. Thus, it is considered as one of the potential vehicle for the spread of infection. Most of the dental instruments which are handy are adequately cleaned and sterilised after use, but the diamond burs are most commonly failed to care for and neglected.^[7] Various medical and dental instruments sterilization guidelines were put-up by various international communities. For example, The International Organization for Standardization provides guidelines for the procedure how the moist heat sterilization occurs and the use of chemical disinfectants for sterilization of medical instruments/devices.^[8] Due to intricate anatomy of dental burs, cleaning and sterilization of it makes difficult to bring off. The spread of infection can occur if there is incompetent sterilization.^[7] Hence, the importance of sterilization of burs has to be understood. Sajjanshetty et al. conducted a comparative study to evaluate different decontamination methods used for dental burs and found that mean colony-forming units/ml of Streptococcus mutans was decreased maximum for autoclave with 80% reduction, 76% reduction for Lactobacilli.^[9]

Sheth et al. in the year 2017 conducted a study to assess newly introduced sterilization unit, named “SteriFast,” and compared with autoclave and glass bead sterilizer for sterilization of endodontic files using biological indicator, found that autoclave and new sterilization device (SteriFast) showed complete sterilization. The files sterilized using glass bead sterilizer showed bacterial growth (80%).^[10] In the present study, Autoclaving showed superior results indicating that it is one of the suitable methods to sterilize dental burs. We also found that 2% glutaraldehyde reduced the maximum microbial load. It mainly acts by denaturating cell wall proteins by acting with cellular constituents.

Eralp et al.^[11] (2006) conducted a study and found 2% glutaraldehyde to be more effective than other disinfectants in disinfecting various dental instruments. Naik et al.,^[12] found that sterilization of dental instruments is successful when instruments underwent sterilization in UV chamber for a duration of 45–60 min. It can also be used in adjunct with other sterilization methods. Inactivation of microorganisms occurs in UV sterilizer due to nucleic acid destruction through thymine dimers induction. It is maximum bactericidal effect was found to occur at 240–280 nm. In the present study, UV sterilization of diamond burs was done for 15 min according to the manufacturers' protocol and found to be less effective in comparison with other methods in reducing the microbial load.

In the present study, the contaminated burs are also subjected to sterilization by immersing the burs in 70% isopropyl alcohol for 10 min. However, it was found to be ineffective due to its low level of disinfection. Alcohols provide bactericidal action rather than bacteriostatic against vegetative spores of bacteria.^[4] Its optimum bactericidal concentration is at 60%–90% solutions in water (volume/volume). When it is diluted below 50% concentration, bactericidal property declines.

In the year 2015, Kumar et al. conducted a study to evaluate the effectiveness of various disinfectants and techniques used in sterilization for disinfection and resterilization of dental burs and endodontic files, found that endodontic files and burs sterilized by autoclaving and glutaraldehyde showed complete sterilization, whereas Quitanet plus solution and glassbead sterilizer showed incomplete sterilization.^[13]

Appropriate sterilization of dental instruments is foremost important and the method of sterilization also plays a key role. If there is inadequate sterilization, life-threatening viruses can spread and pose a risk of increasing morbidity and mortality. Hence, cleaning and sterilizing of each and every instrument including the dental chair after every patient can prevent cross-infection and help in increasing the treatment outcome. In the present study, the maximum reduction in microbial load was observed following sterilization with glutaraldehyde and Autoclaving, followed by ethyl alcohol, UV sterilizer.

Conclusion

Sterilization with 2% glutaraldehyde or autoclave of dental burs is the key step in achieving success in the endodontic procedures with less microbial load which determines the success of pulpectomy procedures.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Mathivanan A, Saisadan D, Manimaran P, Kumar CD, Sasikala K, Kattack A. Evaluation of efficiency of different decontamination methods of dental burs: An in vivo study. J Pharm Bioallied Sci 2017;9:S37-40.
2.	Patil S, Mukhit Kazi M, Shidhore A, More P, Mohite M. Compliance of sterilization and disinfection protocols in dental practice – A review to reconsider basics. Int J Recent Sci Res 2020;4:38050-4.
3.	Aeran H, Sharma S, Kumar V, Gupta N. Use of clinical UV chamber to disinfect dental impressions: A comparative study. J Clin Diagn Res 2015;9:ZC67-70.
4.	Rutala WA, Weber DJ. Guideline for disinfection and sterilization in healthcare facilities; Centers for Disease Control and Prevention 2008.
5.	Sreekumar S, Varghese K, Abraham JP, Jaysa JJ. An in vitro evaluation of the efficiency of various disinfection and sterilization methods to decontaminate dental handpieces. J Dent Res Rev 2018;5:50. [Full text]
6.	Upendran A, Gupta R, Geiger Z. Dental infection control. In StatPearls 2021 Aug 13.
7.	Dioguardi M, Sovereto D, Illuzzi G, Laneve E, Raddato B, Arena C, et al. Management of instrument sterilization workflow in endodontics: A systematic review and meta-analysis. Int J Dent 2020;2020:5824369.
8.	Al-Jandan BA, Ahmed MG, Al-Khalifa KS, Farooq I. Should surgical burs be used as single-use devices to avoid cross infection? A case-control study. Med Princ Pract 2016;25:159-62.
9.	Sajjanshetty S, Hugar D, Hugar S, Ranjan S, Kadani M. Decontamination methods used for dental burs – A comparative study. J Clin Diagn Res 2014;8:ZC39-41.
10.	Sheth NC, Rathod YV, Shenoi PR, Shori DD, Khode RT, Khadse AP. Evaluation of new technique of sterilization using biological indicator. J Conserv Dent 2017;20:346-50. [PUBMED] [Full text]
11.	Eralp A, Gulcin, Sultan N, Ozdemir A. An In vitro evaluation of various disinfectants on different types of contaminated dental materials. Arastirma 2006;30:25-30.
12.	Naik RG, Dodamani AS, Vishwakarma P, Khairnar MR, Jadhav HC, Deshmukh MA. Assessment of efficacy of ultraviolet chamber in disinfecting dental instruments. Asian Journal of Pharmaceutical and Health Sciences 2016;6(4).
13.	Kumar KV, Kiran Kumar KS, Supreetha S, Raghu KN, Veerabhadrappa AC, Deepthi S. Pathological evaluation for sterilization of routinely used prosthodontic and endodontic instruments. J Int Soc Prev Community Dent 2015;5:232-6.