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Year : 2018  |  Volume : 21  |  Issue : 2  |  Page : 226-229
Efficacy of titanium dioxide nanoparticle spray to disinfect mobile phones used by endodontist: A bacteriological study

Department of Conservative Dentistry, SVS Institute of Dental Sciences, Mahabubnagar, Telangana, India

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Date of Submission21-Aug-2017
Date of Decision02-Dec-2017
Date of Acceptance11-Dec-2017
Date of Web Publication22-Mar-2018


Aim: The objectives of this study were to determine the bacterial contamination of the mobile phones that were used by the endodontist in comparison with the general dentist and also to determine the usefulness of titanium dioxide nanospray (TiO2NS) in mobile phone decontamination.
Materials and Methods: Samples from the 60 mobile phones were taken using moist sterile swabs before, 10 min, and 1 week after the use of TiO2NS. Before collection of the swabs, the participants' informed consent was obtained. Samples obtained were cultured on blood agar to identify bacterial isolates.
Results: All 60 mobile phone cultures were found to be culture positive. There was a significant reduction in the mean number of colony-forming units after decontamination with TiO2NS (P < 0.001).
Conclusions: The results from this study showed that the mobile phones may act as an important source of nosocomial pathogens and TiO2NS would be an effective decontaminant. Therefore, it is important for dental professionals to practice routine mobile phone disinfection protocol to reduce the chances of occurrence of nosocomial infections.

Keywords: Bacterial contamination; endodontist; general dentist; mobile phones; nosocomial pathogens; titanium dioxide nanospray

How to cite this article:
Palaniswamy U, Habeeb A, Mohsin M. Efficacy of titanium dioxide nanoparticle spray to disinfect mobile phones used by endodontist: A bacteriological study. J Conserv Dent 2018;21:226-9

How to cite this URL:
Palaniswamy U, Habeeb A, Mohsin M. Efficacy of titanium dioxide nanoparticle spray to disinfect mobile phones used by endodontist: A bacteriological study. J Conserv Dent [serial online] 2018 [cited 2022 Aug 13];21:226-9. Available from:

   Introduction Top

Since 1973, when Cooper had invented the first handheld cellular mobile phone, the communication technology has grown leaps and bounds. The health-care delivery has become more efficient with the advent of telenetwork. India's telecommunication network is the second largest in the world.[1] Cell phones used by dental professionals more so by the endodontist can harbor various potential pathogens and become an exogenous source of nosocomial infections.[2]

Nosocomial infection or hospital-associated infection (HAI) is any disease acquired by the patient undergoing medical care,[3] and about 75% of these infections are present in developing countries.[4] The source of infection may be from the air, dental equipment, hands of dental surgeons, and other staff, which can be considered as exogenous, whereas the bacterial flora in the operative site as endogenous.[5] The pathogens that are usually involved in HAIs include Streptococcus spp., Acinetobacter spp., Enterococcus, Pseudomonas aeruginosa (P. aeruginosa), coagulase-negative staphylococci (CoNS), Staphylococcus aureus Scientific Name Search  (S. aureus), Legionella and Enterobacteriaceae,  Escherichia More Details coli (E. coli).[6] These are growing problems in many health-care institutions.[7]

Singh et al.,[8] Braddy and Blair,[9] Karabay et al.,[10] and Ulger et al.[11] reported the colonization of potentially pathogenic organisms on various objects such as personal digital assistants, pagers, hands and mobile phones. These objects have been suggested as possible vectors for the transmission of nosocomial pathogens from health-care providers to patients. The volume of aerosols and spatter that are produced during dental treatment can cause contamination of surfaces in the dental operatory which is of particular concern, and these surfaces which contain viable organisms can become potential reservoirs for infection,[12] thereby enabling the survival of infectious agents for extended periods unless they are eliminated by disinfection or sterilization procedures.[13]

At present in India, there are no disinfection guidelines for mobile phones of health-care workers that meet hospital standards, nor are there any regulations restricting dental professionals and other staff from carrying these items into the operatory. Since the risk of nosocomial infections involved using mobile phones in dental hospitals has not yet been determined, this study sought to address this issue by screening the mobile phones of endodontist and general dentist for microbial pathogens and to assess the usefulness of titanium dioxide nanospray (TiO2 NS) for decontamination.

   Materials and Methods Top

This study was conducted at SVS Institute of Dental Sciences, Mahabubnagar, India. A total of 60 endodontist and general dentist (n = 30 each) were included in the study. The criteria for participant selection were that they should be involved in the direct patient care and possessed a mobile phone for not <3 months. Before commencing the study, informed consent was obtained from all the participants. Samples were collected from all mobile phones of the participants by rolling sterile cotton swabs moistened with sterile normal saline. All exposed external surfaces of the mobile phones including if any back or flip covers present were also swabbed. Before each sample collection, the investigator wore a new pair of latex gloves to avoid cross-contamination. After the initial sample was obtained, all the external surfaces of the mobile phones were cleaned with sterile gauze and sprayed with TiO2 NS (Armor 8, Armor Life Sdn Bhd, Kuala Lumpur, Malaysia), from a distance of 2 feet. Spray droplets were wiped with sterile gauze and allowed to dry for 10 min, and a repeat swab was taken. All collected samples were sent within 1 h to the Department of Microbiology and Immunology, SVS Institute of Medical Sciences, Mahabubnagar, India, for culture and identification of the bacteria. Swabs were streaked onto blood agar and incubated at 37° C for 24 h. Later, the mean number of colony-forming units (CFUs) was measured. Identification of isolated bacteria was done using Gram stain, morphology, catalase, and oxidase reaction. A slide coagulase test was used to differentiate staphylococcal isolates into S. aureus and CoNS. Antibiotic sensitivity was done using the Kirby–Bauer disc diffusion method on Mueller-Hinton agar.[14] Methicillin-resistant S. aureus (MRSA) was confirmed by testing with cefoxitin disc diffusion test on Mueller-Hinton agar with 4% sodium chloride and incubated at 35°C for 24 h.

Data obtained were analyzed by SPSS 17.0 version (SPSS Inc. Chicago, USA) and GraphPad Prism software 6.0 version (GraphPad Software. Inc, La Jolla, CA). The comparison of datasets was performed by ANOVA test and unpaired t-test. The association between two variables was done by Fisher's exact test; the P ≤ 0.05 was considered as statistically significant.

   Results Top

Samples from sixty mobile phones of endodontist and general dentist showed the growth of organisms. However, the bacterial load (mean CFUs) was significantly higher in the mobile phones belonging to the general dentist. The most common organism detected was CoNS (n = 59, 98%). S. aureus organisms were detected on 15 devices (25%). Other contaminating pathogens were Acinetobacter, Bacillus spp., Diphtheroids, Micrococci, MRSA, Pseudomonas, and Staphylococcus citreus. MRSA organisms were detected in four devices (7%) with no vancomycin-resistant enterococci. The overall rate of bacterial contamination with potentially pathogenic bacteria (S. aureus, MRSA, Acinetobacter, Pseudomonas, and S. citreus) was 47%. There was a significant difference between the two groups in relation to Diphtheriods and bacillus species (P = 0.042 and P = 0.002, respectively) as summarized in [Table 1]. There was a significant reduction in the mean number of CFUs after decontamination with TiO2 NS which was effective even after 1 week (P < 0.001) [Table 2]. The mean CFU counts before, 10 min, and 1 week after TiO2 NS were 236.00 ± 187.50, 17.98 ± 24.55, and 53.10 ± 79.00, respectively, thereby reducing the bacterial load by around 78% even after 1 week of TiO2 NS use.
Table 1: Type of bacterial colonization on mobile phones of endodontist and general dentist in the study

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Table 2: Total bacterial load obtained from mobile phones before, 10 min, and 1 week after spraying of titanium dioxide nanospray

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   Discussion Top

Mobile phones have become an essential part of our day-to-day lives. Every individual is in the possession of a mobile phone at any given point of time. Therefore, it is also important to focus on the possibility of phones acting as potential reservoirs for pathogens. With the advent of touchscreen phones, the same part of the phone touched with fingertips is pressed against face and mouth, thereby upping the chances of infection. Thus, not only patients but also doctors are at the risk of nosocomial infections. The possibility of electronic devices to transmit nosocomial pathogens by their use in the hospitals has been reported by Ulger et al.[11] So far, all the studies that had been performed were limited to medical personnel and health-care workers. The rate and levels of bacterial contamination of mobile phones have not been assessed among endodontist and the general dentist.

Recent attempts to quantify the environmental hazards caused have shown the seriousness of potential cross-contamination.[12] Dental operatory per se is a cause of contamination because of the aerosols generated during dental operatory procedures.[15] Hence, not only the hands of a dental doctor as reported by Brady et al.[16] but also the atmospheric contamination aids in infecting mobile phones. Prolonged use, as well as the products such as disinfectants, composite resins, and alcohol, may increase the permeability of the gloves.[17] An improper adherence to hand hygiene protocol may also aid in mobile phone contamination.

Most of the mobile phones of the participants in the study showed a high rate of bacterial contamination. Many samples also showed contamination with nosocomial pathogens (Acinetobacter, MRSA, Pseudomonas, S. aureus, and S. citreus). Samples collected from endodontist had less microbial load compared to the general dentist, which might be due to the greater awareness and use of rubber dam during operatory procedures and also the restriction of their procedures to conservative dentistry and endodontics.

A mobile phone which is frequently used remain swarm, creating the ideal breeding ground for bacteria. S. aureus and Acinetobacter which are resistant to drying, survive for weeks.[7] In this study, MRSA was isolated from four (7%) mobile phones, which represent a major nosocomial pathogen worldwide.[18] MRSA has been reported to cause necrotizing pneumonia, necrotizing fasciitis, pyomyositis, toxic shock syndrome, and Waterhouse–Friderichsen syndrome.[19]

Acinetobacter spp. were isolated from five (8%) mobile phones. Different terminologies with various definitions such as multidrug-resistant (MDR), extensive drug resistant, and pan-drug resistant have been used to describe their drug resistance. These bacteria are responsible for nosocomial-acquired pneumonia, bacteremia, meningitis, peritonitis, ophthalmitis, endocarditis, and urinary tract infections.[20] Studies have shown that Acinetobacter spp. is associated with 30% of nosocomial infections in the Intensive Care Units (ICUs).[2] Following a similar study in Israel, the use of cell phones in patient care areas have been banned in the concerned hospital, which had identified MDR Acinetobacter baumannii on the hands, cell phones of health-care workers, and patients admitted to the ICU.[21]Diphtheriods, which were isolated from 11 (14%) mobile phones are predominantly nosocomial pathogens. They survive in the form of biofilms and responsible for MDR endogenous infections.[22]

Manufactures of various brands of mobile phones do not provide any disinfection specification for these gadgets. In this study, the photocatalytic property of TiO2 NS reduced the bacterial load. Whenever a TiO2 NS-coated surface gets irradiated, the bacteria gets photokilled by TiO2 nanoparticles by a three-step mechanism (a) reactive oxygen species attack cell wall; (b) disordering the inner cytoplasmic membrane; and (c) killing and decomposing the toxic ingredients of bacteria.[23] It was observed in the study that, TiO2 NS not only gave excellent results 10 mins after its use but also effective even after 1 week.

   Conclusions Top

Mobile phones may aid in nosocomial infections. From our data, it appears that use of TiO2 NS on mobile phones may be effective in reducing microbial contamination even up to 1 week. Disinfection protocol should be made mandatory for the mobile phones to control nosocomial infections.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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Jayalakshmi J, Appalaraju B, Usha S. Cellphones as reservoirs of nosocomial pathogens. J Assoc Physicians India 2008;56:388-9.  Back to cited text no. 2
Hassan AK, Aftab A, Riffat M. Nosocomial infections and their control strategies. APJTB 2015;5:509-14.  Back to cited text no. 3
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Singh D, Kaur H, Gardner WG, Treen LB. Bacterial contamination of hospital pagers. Infect Control Hosp Epidemiol 2002;23:274-6.  Back to cited text no. 8
Braddy CM, Blair JE. Colonization of personal digital assistants used in a health care setting. Am J Infect Control 2005;33:230-2.  Back to cited text no. 9
Karabay O, Kocoglu E, Tahtaci M. The role of mobile phones in the spread of bacteria associated with nosocomial infections. J Infect Dev Ctries 2007;1:72-3.  Back to cited text no. 10
Ulger F, Esen S, Dilek A, Yanik K, Gunaydin M, Leblebicioglu H, et al. Are we aware how contaminated our mobile phones with nosocomial pathogens? Ann Clin Microbiol Antimicrob 2009;8:7.  Back to cited text no. 11
Murray JP, Slack GL. Some sources of bacterial contamination in everyday dental practice. Br Dent J 1957;134:172-4.  Back to cited text no. 12
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Wilker MA, Cockerill FR, Craig WA. Performance Standards for Anti-Microbial Susceptibility Testing: Clinical and Laboratory Standards Institute. 15th informal supplement. M 100-SI5. Vol. 5. Wayne, PA: National Committee for Clinical Laboratory Standards; 2005.  Back to cited text no. 14
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Brady RR, Verran J, Damani NN, Gibb AP. Review of mobile communication devices as potential reservoirs of nosocomial pathogens. J Hosp Infect 2009;71:295-300.  Back to cited text no. 16
Kanjirath PP, Coplen AE, Chapman JC, Peters MC, Inglehart MR. Effectiveness of gloves and infection control in dentistry: Student and provider perspectives. J Dent Educ 2009;73:571-80.  Back to cited text no. 17
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Gordon RJ, Lowy FD. Pathogenesis of methicillin-resistant Staphylococcus aureus infection. Clin Infect Dis 2008;46 Suppl 5:S350-9.  Back to cited text no. 19
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Sunada K, Watanabe T, Hashimoto K. Studies on photokilling of bacteria on TiO2 thin film. J Photochem Photobiol A 2003;156:227-33.  Back to cited text no. 23

Correspondence Address:
Dr. Udayakumar Palaniswamy
Department of Conservative Dentistry, SVS Institute of Dental Sciences, Appanpally, Mahabubnagar - 509 002, Telangana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JCD.JCD_236_17

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