Evaluation of Aerosol Contamination during Ultrasonic Procedures

Background: Operator safety during dental & periodontal treatment is a non-negotiable necessity. The production of airborne material, during dental procedures is obvious to the dentist, dental team and the patient. Aim: The aim of the present study was to evaluate, the colony forming units (CFU) generated from aerosol during ultrasonic procedure in gingivitis and periodontitis subjects that act as a potential risk factor for spread of infectious agents for both operator and patients. Materials and Methods: The present study included 18 subjects which were randomly assigned into 3 equal groups. Group I (Control group) subjects were treated with ultrasonic scaling alone, whereas; Groups II & Group III (Test groups) subjects used pre-procedural mouthrinses before scaling & root planing (Chlorhexidine and Povidone Iodine). Blood agar plates were used to assess the aerosol contamination and were placed at operator’s eye level, subject’s eye & chest level. These plates were then incubated for 72 hours and microbial growth were quantified as colony forming units (CFU/plate). Different colonies were identified by standard biochemical methods. Results: This study showed that the antiseptic mouthrinses significantly reduce the bacterial CFU in the aerosol. Povidone Iodine was found to be superior to Chlorhexidine when used pre-procedurally. Conclusion: The following conclusion was drawn that the use of pre-procedural rinses significantly reduced the aerosol contamination and hence chances of cross-infection in the dental units.


INTRODUCTION
Modern dentistry is founded upon a preventive philosophy in which subjects are encouraged to attend regular examination. 1 Potential problems may be detected at an early stage and appropriate action taken before they become more serious. Treatment of periodontal diseases primarily aims towards the reduction of embedded microorganism in the sub-gingival biofilm. Mechanical debridement of the periodontal pocket has been demonstrated to significantly improve gingival health. 2 Although, there is limited evidence of clinical efficacy and safety, there is a strong trend among clinicians to give preference to ultrasonic instruments for subgingival debridement. 3 Dr. Neha Verma, 1 Dr. Dhritiman Baidya, 2 Dr. Barkha Makhijani, 3 Dr. Neema Shetty, 4 Dr. Aditi Mathur, 5 Dr. Balaji Manohar 6 1,2 Resident, 3 Senior lecturer, 4,5 Reader, 6 Professor and Head, Department of Periodontics

Pacific Dental College and Hospital, Udaipur, India
Many routine dental procedures produce aerosol and splatter composed of various combinations of water like organic particles, such as tissue and tooth dust; and organic fluids, such as blood and saliva. 4 They also contain bacteria (streptococci and staphylococci), protozoa, fungi and blood borne viruses. 5,6 The terminology, "aerosol and splatters" in dental environment were proposed by Micik and collegues [7][8][9][10][11] in their pioneering work on aerobiology. They defined aerosol "as suspensions of liquid and/or solid particles in the air generated by coughing, sneezing, or any other act that expels oral fluids into the air (particle size is 50 micrometers)". The smaller particles of an aerosol (0.5 to 10 µm in diameter) have the potential to penetrate and lodge in the smaller passages of the lungs and are thought to carry the greatest potential for transmitting infections. Splatters are defined as "airborne particles larger than 50 µm in diameter". They stated that these particles behaved in a ballistic manner. This means

18
Journal of Nepalese Society of Periodontology and Oral Implantology : Vol. 1, No. 1, Jan-Jun, 2017 The production of airborne material during dental procedures is obvious to the dentist, the dental team and the subject. Dental health professionals, because of repeated exposures to these microorganisms, are at high risk for developing infectious diseases. Transmission of microorganisms from person to person may occur by direct contact with contaminated tissues or instruments or by aerosols containing infectious agents. 12,13 The major source of potential aerosol contamination in a dental set up is the ultrasonic scaler. As soon as the water spray is emitted from the hand piece of the instrument, it can mix with the subject's saliva and blood present to form a potentially pathogenic aerosol. 14  Hence, the aim of the present study was to evaluate, the CFU generated from aerosol during ultrasonic procedure in gingivitis and periodontitis subjects that act as a potential risk factor for spread of infectious agents for both operator and subjects.
The objective was to compare and evaluate the effectiveness of two commercially available mouthrinses namely Chlorhexidine and Povidone Iodine as a pre-procedural mouthrinses in reducing the number of CFU in aerosol samples. antibiotics, prior to dental procedure and those currently on medication.

MATERIALS AND METHODS
Based on the above criteria 18 subjects which were randomly assigned into 3 equal groups. All the procedure was carried out by a single examiner. Pasquarella et al. 16  To ensure the room was free from aerosol only one subject was treated per day.
For each subject, three agar plates were exposed during the study. Three standardized locations in the same operatory were chosen to be evaluated for aerosol collection i.e.
operator's eye level, subject's eye level and subject's chest level was considered as a parameter in this study as these position determine the risk to the operator and the subject respectively ( Figure 1). After fixing the position of agar plate at same predesignated sites for each subject, the three blood agar plates were kept uncovered to collect samples of aerolized bacteria. Piezo electric ultrasonic scaler was used for scaling and root planing. The tip of the instrument was kept in contact with teeth during the entire scaling procedure.
Power and supply of the coolant were turned to moderate setting. In this combination a fine water spray was generated at the tip of the device.

DISCUSSION
The American Dental Association has recommended that potential contaminated aerosols or splatter should be controlled during dental procedures. 17 While there have been no definitive epidemiologic studies that have linked dental aerosols to disease transmission, the presence of a cloud of contaminated aerosol and splatter, such as that produced by an ultrasonic scaler, should be of concern to the dental practitioner. 18 This study demonstrates that a sufficient amount of aerosol and splatter from the subject was ejected far enough to come into contact with dental personnel, dental auxiliary and subjects.
In the present study, an attempt was made to evaluate and compare the ability of different pre-procedural mouth rinses to lower the microbial counts during the use of aerosol producing ultrasonic scalers. Before starting treatment, almost no bacterial contamination of the air in the dental operatory was found. This was in contrast to the results found by Legnani et al. 19 who found contaminated atmosphere prior to the treatment procedure.
There is a considerable increase in CFU count seen during the  22 who observed the larger salivary droplets generated during dental procedures settle rapidly from the air with heavy contamination on the subject's chest.
This could be explained because of nearer distance and gravity that plays a role in precipitation of the suspended particles of aerosol.
The present study also demonstrates maximum reduction of aerobic colonies using Povidone Iodine at subject's eye level where as Chlorhexidine exhibited maximum reduction at operator's eye level and subject's chest level. This proves that almost 40-50 % reduction of bacterial load is achieved by pre-procedural mouth rinses. Subject's eye level is the second area of concern because it is nearest to the mouth after chest level. It has less contamination because it is against gravity and far away from source of contamination. Operator's eye is least affected but it can't be ignored It should be compulsory for both subject and operator to use eye wear, to prevent contamination during dental procedures.
Harrel and Molinari recommend three levels of defense in the reduction of aerosols. 23 The first recommended layer of defense is personal protective barriers such as mask, gloves and safety glasses. The second layer is routine use of an antiseptic pre-procedural rinse. Chlorhexidine is considered as the "Gold standard" of antimicrobial rinse because of broadspectrum antibacterial activity and substantivity of 8-12 hrs. 24,25 Povidone Iodine as a pre-procedural rinse effectively reduces gingival surface flora prior to oral prophylaxis with ultrasonic scalers and maintains this reduction throughout the duration of the prophylactic procedure. 26 The final layer is the use of high evacuation device.
The American Dental Association advocated protective eyewear for dental health personnel and subjects during dental procedures. 27

CONCLUSION
The results of the present study must be used for increasing awareness and quantifying the risk of operator and subject exposure to aerosolized microbial pathogens in the general dental office, which must be controlled by efficient preventive measures.