Dr Parveen Lone
In dental practice Microorganisms may be inhaled, implanted, splashed onto skin or mucosal surfaces. They can spread by direct contact from one person to other or indirectly through instruments & equipments. The majority of procedures undertaken in dentistry generate aerosols. Infectious agents can spread by airborne transmission through respiratory droplets (droplets > 5 microns in size) generated by a patient when he is coughing, sneezing, talking & large droplets (splash and splatter). This is particularly the case as in dentistry the care provider has to operate in close proximity to the patient using droplet and aerosol generating procedures & it has implications in terms of how close items such as open boxes, gloves, or other materials or instruments are placed to the source of contamination like patient’s mouth or instrument washing sink.
Standard precautions are essential when cleaning the dental surgery environment, handling items contaminated with saliva (e.g. radiographs, dentures, orthodontic appliances, wax rims and other prosthetic work that have been in a patient’s mouth),handling blood , saliva
For asymptomatic carriers there is a dilemma regarding dental management of these symptomless infectious individuals of covid 19. On one hand, aerosol generating or potentially cough or vomit inducing dental procedures increases the risk of cross-infection whilst on the other hand patients’ well-being is compromised if treatment is not delivered. Treatment planning and work practice can therefore be modified to prevent Cross infection. Special precautions can be as follows.
Measures for controlling droplets & aerosol
1) Control the gag, cough & vomit reflux.
By proper patient positioning and behaviour management the patient should be relaxed and comfortable.
Retraction and suction must be performed with care
Intra-oral radiographs, especially bite wing and posterior films, may stimulate the gag reflex and one may consider using extra-oral views for screening purposes e.g. the OPG or the oblique lateral views. Trays may need to be adjusted for impression taking. Very sensitive patients may require anaesthesia of the oral mucosa before impression taking.
Patients suffering from traumatic injuries may have a significant amount of blood in the oral cavity. The reflexes may be induced if blood is swallowed or aspirated so effective evacuation is important
The use of pre-procedural mouthwash
Use of rubber dam isolation
Aerosol and splatter generation is inevitable when ultrasonic scalers, rotary brushes and air prophylactics are used. If conditions dictate, manual scaling and brushing should be used as similar clinical results could be obtained without aerosol generation.
Avoid the use of rotary hand pieces for operative procedures if possible. In selected cases, procedures such as chemo chemical caries removal or atraumatic restorative technique (ART) may be useful.
Minimise the use of a 3-in-1 syringe as this may create droplets due to forcible ejection of water/air.
Rotary instruments are used only after taking all universal precautions to prevent cross infection.
B. Dilution and removal of contaminated ambient air
This could be performed through using one or more of the following measures
High volume evacuation (HVE). HVE prevents or minimises the dispersion of infectious droplet nuclei into the air by removing them at the source as they are emitted. It is important that the filters in the suction apparatus are cleaned General ventilation. Clinics where air-conditioning is not available all windows should be kept open to encourage natural ventilation as much as possible.
The air quality may be improved by controlling the airflow patterns. The ventilation systems should be designed such that fresh incoming air mixes with and dilutes the contaminated ambient air and the mixture is then removed by an exhaust system.
Disinfect air/aerosol generated by Ultraviolet germicidal irradiation (UVGI):
It damages the DNA of microbes rendering them non-infectious and is effective against a wide range of airborne pathogen
Sanitisation of the dental clinic regularly
C Other safety measures
1) Design of premises the design of the premises, the layout of the dental surgery and treatment areas are important factors in implementing successful infection control
The dental operatory and instrument reprocessing rooms must have clearly defined clean and contaminated zones
The contaminated zone is the area which becomes contaminated by splashes & droplets originating from patients mouth (typically within distance of 1.8metrs) because Aerosol generated from patient can extend further than splashed material & also instrument cleaning area
The Clean Zone of dental clinic includes office, staff area, waiting & reception, areas used for storage of supplies & sterilised instrument & equipment
After gloving, staff may move from the clean zone to the contaminated zone but never the reverse direction, workflow for instruments and materials must be from the clean zone to the contaminated zone.
Computer keyboards in the dental operatory may harbour microorganisms and should be covered in treatment areas, and regularly cleaned in non-treatment areas. Patient notes written by hand or electronically must follow a protocol which prevents environmental contamination of the hard copy notes or computer keyboard.
Eating and common room areas for dental staff must be separate from patient treatment area. Lunchroom crockery must not be washed in the hand wash sinks or in instrument wash basins.
Food must not be stored in a refrigerator with dental materials, sealed clinical specimens or medical products such as drugs or blood to prevent cross contamination
Inanimate objects such as toys & other decorative items act as fomites and can spread infections through indirect contact, For this reason, it is prudent to wipe down the hard surfaces of all decorative items in reception and waiting areas on a periodic basis using alcohol based chemicals sprays or detergents & water
Cleaning the environment Equipments & instruments; Floors, walls and curtains pose a risk of disease transmission in a dental practice and must be maintained in a clean and hygienic condition, the practice should develop a schedule to ensure areas including floors, window sills, door handles, and telephone handsets, solid surfaces in the waiting room, Walls, blinds and window curtains in patient care areas must be cleaned daily
Equipment: Surfaces of dental units must be impervious as they may become Working surfaces in the contaminated zone & must be cleaned after every patient by wiping the surface with a neutral detergent or disinfectants like alcohol or hypochlorite solutions based sprays .
All used instruments should be dipped in H2o2, hypochlorite or alcohol to remove the infected debris & wiped with gauge and sterilised using autoclaving, hot air oven ,glass bead sterilisers & formalin chambers as per guidelines
Separate instrument kits for each appointed patient should be autoclaved separately and all instruments and material should be dispensed before treatment to avoid cross contamination.
Management & Disposal of sharps
Used disposable needle syringe empty cartridges of LA solution, burs, needles, scalpel blades, orthodontic bands, endodontic files and other single-use sharp items must be discarded in an approved clearly labelled, puncture and leak-proof containers directly. Bags and containers for medical waste should be appropriately colour coded and labelled as biohazard or medical waste &removed by a licensed contractor. Medical waste and hazardous chemical waste (which includes some blood, saliva, chemicals and mercury) must never be disposed of at local refuse tips that use compaction of an open landfill.
ADA’s Guidelines for Infection control contains a significant number of additions to the second edition published in 2012. In addition to the above all protocol.
In addition to above all protocol prescribed of covid 19 may be followed like
Use of PPE which including gowns/over garment, hair covers, N95,99, face masks, waterproof aprons, boots or shoe cover, goggles, face shield and head cover Keeping effective screening protocols, providing hand sanitizer & facemask to patient & attendants, physical distancing, prior appointment by telephone, limiting the no attendants with patient to avoid crowding in waiting areas.
It is the duty of all of us to maintain a safe practice and environment to prevent cross infection by following the universal precautions.
The author is Prof & Head Oral & maxillofacial surgery (OMFS) Indira Gandhi Government Dental College Jammu (IGGDCJ)
Dr Parveen Lone