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   Table of Contents    
ORIGINAL ARTICLE
Year : 2016  |  Volume : 20  |  Issue : 3  |  Page : 273-278  

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study


1 Department of Periodontics, The Oxford Dental College, Bengaluru, Karnataka, India
2 Department of Periodontics, Government Dental College, Victoria Hospital Campus, Fort, Bengaluru, Karnataka, India

Date of Submission14-Aug-2014
Date of Acceptance23-Feb-2016
Date of Web Publication4-Jul-2016

Correspondence Address:
Shobha Krishna Subbaiah
Department of Periodontics, The Oxford Dental College, 10th Mile, Hosur Main Road, Bommanahalli, Bengaluru - 560 068, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-124X.182599

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   Abstract 

Background: Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Materials and Methods: Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A - dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. Results: In Group A – 15 out of thirty samples were contaminated, in Group B – all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Conclusion: Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.

Keywords: 16S ribosomal RNA sequencing, aerosol contamination, contact lenses, protective eyewear, ultrasonic scaler


How to cite this article:
Afzha R, Chatterjee A, Subbaiah SK, Pradeep AR. Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study. J Indian Soc Periodontol 2016;20:273-8

How to cite this URL:
Afzha R, Chatterjee A, Subbaiah SK, Pradeep AR. Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study. J Indian Soc Periodontol [serial online] 2016 [cited 2019 Oct 16];20:273-8. Available from: http://www.jisponline.com/text.asp?2016/20/3/273/182599


   Introduction Top


Periodontitis is an inflammatory disease affecting the supporting structures of the teeth. The goal of periodontal therapy is to eliminate disease and restore the periodontium to a state of health which includes comfort, function, and esthetics that can be maintained adequately by both the patient and dental professional. After thorough scaling and root planing, a profound reduction in motile rods, Spirochetes, and putative pathogens, such as Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans, and an increase in coccoid cells occur.[1]

Although ultrasonic scalers are used routinely on patients, there are a few deleterious effects or hazards associated with its use. For example, it may produce thermal damage to the tissues, aerosol production contaminated with blood, and there is a high electromagnetic radiation emitted with these devices that can interfere with electrical devices such as cardiac pacemakers, neurologic disturbances of the hand caused by vibration such as “white finger” and hearing loss.[2]

Aerosols are liquid and solid particles, 50 μm or less in diameter, suspended in air. Aerosol from ultrasonic instrumentation always contains blood and lingers in the air for 30 min or longer in the entire operatory and areas of the dental office outside the operatory.[1],[3]

The aerosol produced by sonic and ultrasonic instrumentation may contain potentially infectious blood- and air-borne pathogens. Pneumococci, staphylococci, alpha hemolytic, streptococci, and Mycobacterium tuberculosis are among the bacteria that have been found in dental aerosols. Aerosols also subject dental personnel and patients to many viruses including herpes simplex virus, hepatitis virus, influenza virus, common cold viruses, Epstein–Barr virus, and Cytomegalovirus. Additional concerns are pathogens that do not originate from patients but are from the contaminated water lines of the dental unit or the ultrasonic device. Putative pathogens such as Pseudomonas species and Legionella pneumophilia have been isolated from dental unit water and can become aerosolized by an ultrasonic scaler.[1]

The microorganisms which have been isolated in dental aerosols are associated with various diseases such as staphylococcal infection, tuberculosis, viral infections, conjunctivitis, and other skin infections.

Culture plates opened for 1 min during use of high-speed handpieces on five tuberculosis patients with positive sputum were all positive up to 48 inches away.[4],[5],[6]Serratia marcescens placed in dental unit water supplies as a tracer microorganism have been recovered over 6 ft away from an operating high-speed handpiece.[3]

Bacterial aerosols are an important consideration for infection control and occupational health hazards in the dental clinic since infective agents can be transmitted via aerosols to patients or dental staff.[7],[8],[9] To prevent this transfer of infection, it is recommended that patients with infectious disease be treated only with hand scalers. Unprotected patients may be more susceptible to infection from the aerosol than dental personnel who are wearing protective barriers such as masks, gloves, eyewear, and clinical clothing.[1]

This study is the first of its kind as per our knowledge where we investigated the contamination of contact lenses after scaling and root planing with piezoelectric ultrasonic scalers. The contact lens wearers are at great risk of developing ocular infections because of incorrect usages and unhygienic maintenance of contact lenses. In most of the cases of corneal ulcers or bacterial keratitis, the microorganisms cultured from the eye have also been isolated from the contact lenses. Many of these adverse responses are produced as a result of bacterial colonization of the contact lenses. Concerns about microbial contamination of contact lenses and the adverse responses associated with its use have been expressed since their inception. However, there are no reported cases or studies of microbial contamination of contact lenses after dental treatment procedures such as scaling and root planing with ultrasonic scalers which produce aerosol or splatter.

Keeping the above facts in mind, the present study was performed to evaluate aerosol contamination of contact lenses of the dentist after scaling and root planing with ultrasonic scalers, qualitative analysis of microorganisms on contact lenses of the dentist, to determine the effectiveness of protective eyewear.


   Materials and Methods Top


Source of data

The participants for this study were selected from the outpatient section in the Department of Periodontics, The Oxford Dental College, Hospital and Research Centre, Bangalore, India. Thirty subjects (ten males, twenty females aged between 35 and 50 years) diagnosed with moderate to severe chronic periodontitis were enrolled in this study. The study protocol was approved by the ethical committee of the institution and informed consent was obtained from the participants.

Selection criteria

Inclusion criteria

  • Subjects aged between 35 and 50 years
  • Moderate to severe chronic periodontitis (as per the American Academy of Periodontology classification)
  • Minimum of twenty teeth present
  • No history of periodontal or antibiotic therapy in the preceding 6 months
  • Thirty dentists who wear contact lens without any history of eye infection in the last 6 months.


Exclusion criteria

  • Subjects with definite contraindications for the use of ultrasonic and sonic scaling devices, for example, patients with known communicable diseases that can be transmitted by aerosols
  • Subjects with a cardiac pacemaker
  • Subjects with respiratory diseases such as chronic pulmonary disorders
  • Immunocompromised subjects
  • Subjects with titanium implants, which can be etched or gouged
  • Pregnant or lactating mothers.


After subject selection, 15 subjects were randomly assigned to each treatment group (using a computer-generated system- The randomization scheme was generated by using the Web site Randomization.com, ), Group A – 15 dentists wearing contact lenses and protective eyewear, Group B – 15 dentists wearing contact lenses only. Daily disposable contact lenses (Bausch and Lomb Soflens - daily disposable) were used by the dentists in both the groups. The lenses were aseptically worn after wearing a fresh sterile particle free glove (Fisher Scientific particle-free gloves). Sterile water was used in the booster. Scaling and root planing were rendered with piezoelectric ultrasonic scalers (piezoelectric scaler [Biosonic]) in combination with high volume evacuation (HVE) for about 30 min in both the groups. After scaling and root planing with ultrasonic scalers, the lenses were aseptically collected wearing a fresh sterile particle free glove and transferred into a sterile test tube containing brain heart infusion broth M210 (composition-ingredients gm/L, calf brain, infusion from 200.000 beef heart, infusion from 250.000 proteose peptone 10.000 dextrose 2.000 sodium chloride 5.000 disodium phosphate 2.500 final pH at 25°C - 7.4 ± 0.2). The samples were then subjected to microbiological analysis (culture and 16S rRNA [16S ribosomal RNA] gene sequencing). All the samples were cultured on brain heart infusion broth M210 and incubated in aerobic and anaerobic conditions for 24–48 h at 37°C. A variety of molecular techniques are used in identification and estimating the phylogenetic relatedness of prokaryotes, the comparison of 16S rRNA isolated from thousands of strains is of particular importance. 16S rRNAs are the best studied molecular markers since ribosomes have a central role in gene expression. 16S rRNAs of bacteria and Archaea are used to determine the phylogenetic relationship among these organisms. The advantage of using 16S rRNA is that it is found in all organisms and large enough molecules provide a significant number of nucleotides to compare sequence.

Statistical analysis

Power analysis calculations were performed before the study was initiated. The statistical analysis was performed using commercially available software (SPSS version 10.5, IBM, Chicago, IL, USA). Tables and graph were generated using Microsoft Word and Excel. Contingency coefficient test was used for intergroup comparisons [Figure 1]. It gives the association between the groups and the responses. Statistical significance was defined as P < 0.01, which is highly significant.
Figure 1: Contingency coefficient test

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   Results Top


Culture

All the samples were cultured on brain heart infusion broth M210 and incubated in aerobic and anaerobic conditions for 24–48 h at 37°C. After 48 h of incubation, in Group A (contact lens + with protective eyewear) - 15 out of thirty samples [Figure 2] and in Group B (contact lens + without protective eyewear) - all the thirty samples were contaminated [Figure 3] and [Table 1]. Out of sixty samples, 45 were contaminated and of 45 samples, five samples showed fungal growth (two samples in Group A and three in Group B [Figure 4], [Figure 5] and [Table 1]). Forty out of sixty samples were analyzed using 16S rRNA sequencing.
Figure 2: Group A showing fungal and other bacterial colonies

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Figure 3: Group B showing bacterial growth around the lens

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Table 1: Contamination groups cross tabulation

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Figure 4: Group A showing fungal growth

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[Figure 5]

Histopathological examination

Grams' staining was done for forty contaminated samples which revealed most of the samples were Gram-positive bacteria [Figure 6] and [Figure 7].
Figure 6: Group A and Group B showing Gram positive bacteria AT 4X

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Figure 7: Group A and Group B showing Gram positive bacteria AT 20X

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16S ribosomal RNA sequencing

Out of sixty samples, 45 were contaminated. In 45 samples, five showed fungal growth. Forty contaminated samples were analyzed using 16S rRNA sequencing. The 16S rRNA sequencing results revealed that in Group A - ten samples were contaminated with Streptococcus mutans, three with Staphylococcus aureus, and two with fungi. In Group B – 21 samples were contaminated with S. mutans, six with S. aureus, and three with Fungi. (In total 31 samples were contaminated with S. mutans strain, nine with S. aureus and five with Fungi.) Overall, the results of this study indicate low microbial contamination of contact lens in Group A (contact lens with protective eyewear) when compared to Group B (contact lens without protective eyewear) which is statistically significant (P < 0.01) [Table 2]. However, even after wearing protective eyewear, there is contamination of the contact lens which can be very hazardous to the eyes [Flowchart 1 [Additional file 1]].
Table 2: Symmetric measures

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   Discussion Top


Disease transmission and barrier techniques during dental treatment have been areas of recent concern in dentistry. The interest in dental aerobiology has been stimulated by concern with the obvious splatter caused by the visible particles emanating from the patient's mouth during dental procedures. The driving force to conduct this study is an observation that dentists do not wear protective eyewear while rendering treatment which is very important in preventing damage to the eyes. The interest of the present study was to determine aerosol contamination of contact lenses of the dentist after scaling and root planing using a piezoelectric scaler in combination with HVE, qualitative analysis of microorganisms on contact lenses of the dentist, and to determine the effectiveness of protective eyewear in preventing the contamination of the contact lens.

The oral cavity harbors numerous bacteria and viruses from the respiratory tract, dental plaque, and oral fluids. It is a unique environment which provides an ideal medium for the growth of bacteria. Any dental procedure that has a potential to aerosolize the saliva will cause airborne contamination with organisms from some or all of these sources. Contamination of clothing and skin by touches or splashes is unavoidable in clinics. The hazards of cross contamination are far reaching. Any cross infection can result even in the death of the person in case of an immunosuppressed patient.

Ultrasonic scalers are known to produce a fine spray called aerosol or splatter, and these aerosols are often produced from areas of significant disease activity including bleeding.[10] Aerosols may be heavily contaminated with oral organisms and present a considerable microbial challenge to the dentist, patients, and the nursing staff. It contains infected droplets which remain suspended in the environment for about 30 min or longer and can be inhaled into the lungs. The contaminated water in dental chair waterlines is yet another source for transmission of infection.[11] This may potentially contribute to the transmission of infections through the dental office, which has become a source of increased concern to the dental profession.

This study is the first of its kind as per our knowledge where we investigated the contamination of contact lenses of the dentists after scaling and root planing with ultrasonic scalers. Scaling and root planing was rendered for 30 min after which the lenses were aseptically collected and cultured in both aerobic and anaerobic conditions. The microbial contamination of contact lens in Group A was less when compared to Group B, (statistical significance was defined as P < 0.01, which is highly significant) proving the importance of wearing protective eyewear. However, even after wearing protective eyewear, there was contamination of the contact lenses which can be very hazardous to the eyes. In the present clinical and microbiological comparative study, the sample size can be considered as one of the limitation.

Ultrasonic scalers generate aerosols with bacteria peaking at over 300 CFU/cu ft of dental operatory volume.[3] Barnes et al. demonstrated that the aerosol produced by the in vivo use of an ultrasonic scaler on periodontally involved teeth was contaminated with blood and that the contamination occurred regardless of the level of inflammation.[10] In a study by Bhat et al., sterile swabs were used to collect samples from the chest area and pocket area of the aprons/overcoats of dental students which were then cultured, the results showed that there was microbial contamination of overcoats of dental students.[12]

Many studies have confirmed that an aerosolized bacterial contamination is produced during the use of ultrasonic scalers and other dental equipment that produce an aerosol spray.[10],[13],[14] Miller et al. demonstrated that dental operations involving air and water sprays in combination with rotating instruments may cause levels of contamination exceeding those produced by common oral activities.[15] They showed that a sneeze and the use of the air turbine handpiece produced comparable aerosols and splatter. A four-fold increase of airborne bacteria has been observed in areas where aerosol producing equipment was used.[16] A considerable bacterial challenge exists in the aerosol produced by ultrasonic scalers, and it is probable that viruses and bacteria may be spread via this route.[17] The traditional view of this bacterial contamination in the dental office is that these are nonpathogenic bacteria.[18] However, studies have linked an increase in respiratory illness to the use of ultrasonic scalers.[19],[20] With the reported resurgence in bacterial diseases and the presence of other pathologic organisms with the potential for airborne transmission, there is an increased concern about aerosol contamination and decreased air quality in the dental office. Bacterial contamination from ultrasonic scaler due to aerosol has been noted in the past. According to the Center for Disease Control Guidelines for Infection Control in Dental Health-Care Settings (2003), preventive measures to control dental office air contamination include universal precautions, which consist of dental staff protective equipment (gown, mask, gloves, eyeglasses), preprocedural patient mouth-rinsing with antimicrobial products (such as chlorhexidine gluconate), operatory isolation (rubber dam), vacuum and electrostatic extraction of aerosols during dental procedures, air circulation methods (ventilation and air conditioning systems), air filtration systems for solid particles and mercury, ultraviolet lamps, disinfectants, and microbial controls for instruments and surfaces.

People choose to wear contact lenses for many reasons such as visual, esthetics, and cosmetics which are often motivating factors for people who would like to avoid wearing glasses or change the appearance of their eyes. Occasionally, adverse responses to contact lens wear occur such as microbial keratitis, contact lens-induced acute red eye, contact lens-induced peripheral ulcers, and infiltrative keratitis.[21] These adverse responses are frequently caused by bacterial contamination of the contact lens surface. One of the initial steps in the development of the bacterially driven adverse responses is the binding of bacteria to a contact lens.

Contact lenses do not protect the eyes and can increase the risk of exposure to microorganisms if contaminated fluids gain access beneath the lens. Eyes are particularly vulnerable to injury by high-velocity particles/debris generated during use of high-speed handpieces and ultrasonic scalers. It has been reported that the environment, the type of contact lens, the duration of wear, and the type of contact lens cleansing solution determined the microbial load on the contact lenses.[22],[23] The normal ocular microbiota in the absence of contact lens wear is composed almost exclusively of bacterial types such as Corynebacterium sp. and Propionibacterium sp.[24],[25]

Martins et al. observed the presence of fungi, parasites and bacteria in contact lens swabs cultures.[26] Several studies have examined the ability of bacteria to adhere to contact lenses. Subsequent to adhesion, it is likely that bacteria further colonize the lens surface by growing on that lens surface. These bacteria do not make up part of the normal ocular microbiota. Hume and Willcox demonstrated that S. marcescens was able to grow on a contact lens after adhesion to contact lenses coated with an artificial tear film.[27] The unique structure of the human eye, the use of contact lenses and the constant exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by microorganisms.


   Conclusion Top


Protective measures recommended to reduce the risk of infection from aerosols may be classified as physical, chemical, and personal safeguards. This study highlights the importance of protective eyewear in the prevention of contamination of the contact lenses. But, even after wearing protective eyewear there was contamination of the contact lenses. Going by the results of this study, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn it is recommended to wear protective eyewear. Limitations of the study include sample size and absence of a negative control. Therefore, similar studies with a larger sample size and a negative control are required to affirm the observations of our study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Pattison GL, Pattison AM. Scaling and root planing. In: Newman MG, Takei HH, Carranza FA, editors. Clinical Periodontology. 9th ed. Philadelphia: W.B. Saunders Company; 2002. p. 631-45.  Back to cited text no. 1
    
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Wirthlin MR, Choi JH, Kye SB. Use of chlorine dioxide mouthrinse as the ultrasonic scaling lavage reduces the viable bacteria in the generated aerosols. J West Soc Periodontol Periodontal Abstr 2006;54:35-44.  Back to cited text no. 3
    
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Barnes JB, Harrel SK, Rivera-Hidalgo F. Blood contamination of the aerosols produced by in vivo use of ultrasonic scalers. J Periodontol 1998;69:434-8.  Back to cited text no. 10
    
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McEntegart MG, Clark A. Colonisation of dental units by water bacteria. Br Dent J 1973;134:140-2.  Back to cited text no. 11
    
12.
Bhat SS, Bhat VS, Rao LV, Mathew RT. A study on microbial contamination of overcoats of dental students. Kerala Dent J 2013;36:105-10.  Back to cited text no. 12
    
13.
Bentley CD, Burkhart NW, Crawford JJ. Evaluating spatter and aerosol contamination during dental procedures. J Am Dent Assoc 1994;125:579-84.  Back to cited text no. 13
    
14.
Harrel SK, Barnes JB, Rivera-Hidalgo F. Aerosol and splatter contamination from the operative site during ultrasonic scaling. J Am Dent Assoc 1998;129:1241-9.  Back to cited text no. 14
    
15.
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. 15
    
16.
Gehring F. Total bacterial count and the occurrence of Streptococcus mutans and Streptococcus sanguis in the air of various work areas. Dtsch Zahnarztl Z 1976;31:149-52.  Back to cited text no. 16
    
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Holbrook WP, Muir KF, Macphee IT, Ross PW. Bacteriological investigation of the aerosol from ultrasonic scalers. Br Dent J 1978;144:245-7.  Back to cited text no. 17
    
18.
Miller RL, Micik RE. Air pollution and its control in the dental office. Dent Clin North Am 1978;22:453-76.  Back to cited text no. 18
    
19.
Allsopp J, Basu MK, Browne RM, Burge PS, Matthews JB. Survey of the use of personal protective equipment and prevalence of work related symptoms among dental staff. Occup Environ Med 1997;54:125-34.  Back to cited text no. 19
    
20.
Rosen S, Schmakel D, Schoener M. Incidence of respiratory disease in dental hygienists and dietitians. Clin Prev Dent 1985;7:24-5.  Back to cited text no. 20
    
21.
Holden BA, Sankaridurg P, Jalbert I. Adverse responses – Which ones and how many. In: Sweeney DF, editor. Silicone Hydrogels – The Rebirth of Continuous Wear of Contact Lenses. 1st ed. Oxford: Butterworth Heinemann Publishers; 2000. p. 150-213.  Back to cited text no. 21
    
22.
Iskeleli G, Bahar H, Unal M, Artunay O, Akova N, Torun MM. Microbiologic evaluation of frequent-replacement soft contact lenses. CLAO J 2002;28:192-5.  Back to cited text no. 22
    
23.
Lee KY, Lim L. Pseudomonas keratitis associated with continuous wear silicone-hydrogel soft contact lens: A case report. Eye Contact Lens 2003;29:255-7.  Back to cited text no. 23
    
24.
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25.
Fleiszig SM, Efron N. Microbial flora in eyes of current and former contact lens wearers. J Clin Microbiol 1992;30:1156-61.  Back to cited text no. 25
    
26.
Martins EN, Farah ME, Alvarenga LS, Yu MC, Höflin-Lima AL. Infectious keratitis: Correlation between corneal and contact lens cultures. CLAO J 2002;28:146-8.  Back to cited text no. 26
    
27.
Hume EB, Willcox MD. Adhesion and growth of Serratia marcescens on artificial closed eye tears soaked hydrogel contact lenses. Aust N Z J Ophthalmol 1997;25 Suppl 1:S39-41.  Back to cited text no. 27
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2]



 

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