Hygiene in the dental office

Asepsis

• a set of precautions and procedures to prevent microbial contamination of the sterile environment (e.g. including the operating theatre)
• disinfection of the hands of the operating team
• sterile clothing of the operating team (gown, gloves, surgical caps, mouth and nose drapes, surgical gowns...)
• patient skin disinfection
• protection of the operating field with sterile drapes
• preparation of sterile instruments and materials for operating tables
• treatment of feeding cords and hoses with sterile cloth sleeves
• disinfection of operating theatre rooms and air disinfection

Disinfection

Physical

Boil in water

atmospheric pressure, exposure 30 minutes, distilled water under pressure (Papin pot principle) - 0.1-0.15 MPa, exposure 20 minutes

objects - metal, glass, rubber, ceramics, stoneware, porcelain, textiles, thermostable plastics

Boil in oil

silicone lubricating oils, 150 °C, 30 minutes (!!! steam explosive !!!)

then centrifugation (removal of excess oil)

dental handpieces and elbows (must be disassembled and cleaned first)

turbines - steam sterilisation up to 135 °C (contains plastic parts)

other handpieces - hot air sterilisation up to 180 °C (all metal)

Washing and steaming appliances

temperatures above 90 °C, follow the procedures specified by the manufacturer

• UV radiation

germicidal emitters - direct and indirect irradiation of space for air disinfection

bactericidal action - wavelength 253.7-264 nm

only on the surface of objects

mercury vacuum silicon lamps

long-term (overnight) exposure

• other methods

filtration, annealing, incineration, pasteurisation (heating to 60-65 °C for 30 minutes, then heating to 85-90 °C or 134 °C for a few seconds and rapid cooling)

hot air flow in dryers (110 °C for 30 minutes)

Chemical

solutions or aerosols of chemical disinfectants of a specified concentration

specified duration of action - spectrum of effectiveness

often toxic substances (limited concentration only)

• spray disinfection

foam, aerosol

• disinfection by wiping, washing or immersion in a disinfectant solution for a specified time (usually 30 minutes) or until dry

Physico-chemical

simultaneous action of physical and chemical processes

• paraformaldehyde disinfection
• disinfection by boiling - in water, 60 °C, disinfectant additive in washing, washing and cleaning machines

Substances used for chemical disinfection:

• inorganic acids – HNO3, HCl, H2SO4

exceptionally for disinfection of glass and porcelain (more in industry and veterinary medicine)

• alkalis

NaOH, KOH 5–10% – cleaning and disinfection of drill bits (they dissolve detritus)

Ca(OH)2 – wall bleaching, gross disinfection

• organic acids – citric, acetic, lactic, benzoic (food preservatives)
• peroxyacids – peracetic, perpropionic, permravenic - vapours, solutions, aerosols

wide spectrum of action - microbes including mycobacteria, spores and viruses

40% peracetic acid = Persteril

• oxidizing agents
• hydrogen peroxide

3% - disinfection of wounds

6–10% - periodontal rinsing in periodontology

30% - endodontics (Perhydrol)

• potassium manganate (hypermanganese) – 0,1–0,3% - mouth rinses, treatment of skin lesions
• soaps – solid (sodium), oily (potassium) - emulsification and dissolution of fats

mechanical cleaning of instruments and body surface

bactericidal action - penetrate the body of microorganisms

disinfectant soaps - from naphthenic acids, addition of disinfectants (hexachlorophenone) - for surgical hand washing

• alcohols – degreasing, poultices, sometimes hand disinfection
• halogens – chlorine and iodine products
• chlorine products – chlor lime, chloramines, chlorseptol

salt content HClO - decomposes in water - oxygen in the nascent state

efficiency decreases rapidly (no longer effective after 60 minutes)

disinfection of laundry and containers, in powder for sinks, aerosol for air disinfection

chloroseptol - 0.25-0.5% - hand disinfection, disinfection of rubber gloves and drains

• iodine products

iodine tincture - 5% alcohol solution

iodophores - complex compounds, large spectrum of effectiveness, less allergies

Iodisol - disinfection of skin and mucous membranes, 1:20 for gargling and mouth rinses

Iodonal - surface and coarse disinfection

• metal compounds – Hg and its compounds, Ag, Sn
• mercury – inorganic compounds are not used (toxicity)
• organic compounds – less toxic but also less effective

Famosept Super

1% solution of phenylhydrargyrum boricum

storage of sterile instruments, mucous membrane disinfection, wound flushing, hand disinfection

• aldehydes

wide spectrum of effectiveness - bacteria, fungi, viruses, spores (in sufficient concentration)

disadvantages - irritation, pungent odour

• formaldehyde – colourless gas with a characteristic pungent odour

36-40% aqueous solution = formalin

2-20% - coarse disinfection

part of instrument storage solutions and surface disinfection solutions

vapours - disinfection of textiles, plastics, instruments (in closed chambers)

tablets, gels - for small instrument cartridges (release CH2O gas)

• glutaraldehyde – 2% – good and rapid effect on vegetative forms of microbes

longer exposure - even spores

3% - also effective against hepatitis virus

decontamination of endoscopes and other instruments

1-2% solution + Na2CO3 - disinfection of fingerprints at 10 minutes exposure (alginates)

• cyclic compounds – phenolic and cresol preparations, halogen and diphenyl derivatives

the effect can be increased by combining with alcohol, certain organic compounds, soap

• phenol – part of instrument storage solutions

Chlumsky's solution (solutio fenoli comphorata) - disinfectant inserts into root canals, it is used to fill mule drains

• surfactants

anioactive (carboxyl soaps, sulphonate detergents)

cationic (quaternary ammonium compounds)

amphoteric

non-ionogenic

germicidal, non-virucidal and sporocidal

not to be combined with soaps and strong oxidizing agents

• Ajatin – quaternary ammonium base with high phenol coefficient

supplied as a 10% solution and diluted accordingly

0.5-1% - surface disinfection of skin, rinses and instrument storage

Ajatin tincture = 1% alcohol solution

disinfection of the operating theatre

• Septonex

sodium carbonate is often added during chemical disinfection

facilitating the penetration of disinfectants into the body of microorganisms

speeds up the disinfection process

increases the bactericidal effect of soapy water and sublimate in particular

used in a 2% solution

Sterilization

Physical

Steam sterilization

sterilization with saturated steam under pressure, the most reliable, the most used today

autoclave

• Autoclave

pressure boiler with double wall, tight, screw-closable lid

connected via a pressure reducing valve to the central steam supply or to the steam generating plant itself (for electric or gas heating)

thermometer, pressure gauge, vent valve

internal compartment connected to vacuum extraction

measuring recording device - operation control

preparation of instruments to be sterilised:

containers and cassettes with perforated walls or lids (the openings are closed with a sliding cuff after sterilisation)

Lukasterik - low-pressure polyethylene or paper packaging

instruments are sealed or wrapped in it

operation:

heating time

equilibration time - steam is introduced into the sterilisation compartment with simultaneous air extraction

sterilisation (exposure) time - determined for each instrument for the respective pressure and temperature values and for the different materials

drying time

temperature pressure overpressure exposure

°C kPa bar kPa bar min 121 205 2,05 105 1,05 20 134 304 3,04 204 2,04 10

Hot air sterilisation

exploits the effects of hot dry air at certain parameters

simplicity of installation and operation

safe results

higher temperatures must be achieved

longer exposure

instruments:

metal, glass, porcelain, ceramic, stoneware

cannot be sterilised - textiles, rubber, pulp (heat damage)

• Hot air sterilizers - well insulated thermal cabinets with a volume of 30-400 l

built-in fan for controlled air circulation

indoor - electric heating (controlled by adjustable thermostat, external control by thermometer located outside the unit)

temperature - 50-200 °C

exposure - inversely proportional to temperature

dependent on the quality and quantity of sterilised material

empirically determined for each type of apparatus

includes the time required for instruments to cool down to 80 °C

exposure temperature (min) 160 °C 60 170 °C 30 180 °C 20

mainly used after working hours (time consuming)

less used today, replaced by autoclaves

Radiation sterilisation

uses the effects of ionizing radiation (cold sterilization)

electromagnetic waves, gamma rays, ultra-hard X-rays

radiation source = cobalt isotope 60Co

products may be sealed in plastic packaging

no need for air extraction

economically costly

demanding safety precautions

mainly in industry - sterilisation of disposable items (needles, syringes...)

Chemical

use - sterilization of plastic materials that do not tolerate high temperatures (implant prostheses...)

• formaldehyde sterilization

formaldehyde in a vacuum device under given parameters, temperature 60-80 °C

• ethylene oxide sterilization

ethylene oxide - in liquid (below 10,7 °C) and gaseous form

Hand hygiene

the hands are the most important agent in the transmission of infection !!!

microbial flora

transient - adheres to surfaces when touching infected objects

eliminated by normal handwashing

resident (permanent) - deep in the skin, at the mouth of sebaceous and sweat glands

only partially eliminated by normal hand washing

Hand washing

removal of dirt using liquid soap and water for 30 seconds

drying - disposable towel

Hygienic hand washing

removal of impurities and partly of the transitory flora before surgical hand disinfection

washing hands including forearms with liquid soap and disinfectant for 1-2 minutes

alcohol disinfectants, rinse with drinking water

drying with a sterile towel

washing hands including forearms with liquid soap without disinfectant 2 x 5 minutes using sterile toothbrush, rinsing with drinking water, drying with sterile towel

Hygienic hand disinfection

elimination of transient flora

performed after microbial contamination of the hands

immersion of hands in disinfectant, rinsing with drinking water after a specified time, drying with a sterile drape

alcohol preparation - rubbed into dry hands for a specified time, do not rinse

after repeated disinfection, treat hands with regenerating cream

Surgical hand disinfection

elimination of transient microflora, blocking of resident flora in the inner layers of the skin

• classical procedure (surgical hand washing)

the hands, including the forearms, are washed for 2 × 5 minutes using a sterile brush, rinsed with drinking water during the washing

drying of the hands with a sterile drape

washing hands with 70% alcohol for 3 minutes (Sterilium Sagrosept, Deladerm...)

immersion of the hands for 1 minute in a disinfectant solution (Iodonal, Chloramine...)

drying with a sterile drape

• quick procedure (abbreviated hand washing)

hands including forearms are washed with warm water and soap for 1 minute using a sterile toothbrush, rinsed with potable water and dried with a sterile drape

immersion of hands in disinfectant solution for 2-3 minutes

rinsing hands with distilled water

immersion of the hands in the disinfectant solution again for 2-3 minutes

drying with a sterile cloth

• procedure for the use of alcoholic disinfectants

hygienic washing of hands and forearms with disinfectant liquid soap and water for 1-2 minutes (or use a sterile toothbrush on the nail beds)

disinfectant soaps - C40, Triformin Mehaso, Primasept M, Lamyderm...

dry hands thoroughly with a sterile drape

treatment with an alcohol disinfectant containing a residual substance recommended for surgical hand disinfection

the amount of solution recommended by the manufacturer is repeatedly rubbed into the skin of the hands and forearms for a specified time (usually 2 x 2,5 minutes)

the hands should be kept moist for the entire duration of the application (i.e. 5 minutes)

Gloves

necessary to change gloves with each patient (examination, treatment)

this is preceded by hygienic hand disinfection

surgical procedures - surgical hand washing, putting on sterile gloves

General principles of operational hygiene in dental establishments

The dental workplace is a place with a significant risk of infection transmission due to contact of unprotected hands of the doctor with the patient's mouth, inhalation of infectious aerosol, etc.

Decontamination of surfaces and environments of surgeries and operating theatres

• thorough mechanical cleaning and disinfection
• two-stage
• one-stage – cleaning and disinfecting agents, or combination of disinfectants with detergents (Persteril, Chloramine B - combination with Jar, Pur, Corona, Sapon...)
• disinfectants - effectiveness against bacteria, yeasts, viruses
• Surfaces – decontamination - wiping with a cloth, rinsing, spraying
  • in records - area (section) treated, method of treatment, disinfectant, frequency of decontamination
  • painting - once a year outside the facility
  • construction work - prohibited during operation
• Air
  • physical methods (ventilation, UV radiation (germicidal lamps), air conditioning...)
  • chemical methods (formalin, Persteril) - not recommended - toxicity, irritation, odour
• Extraction equipment
  • for extraction of saliva, blood, aerosol... + narcosis devices
  • flushing hoses and equipment with warm water and detergent after each patient

Cleaning

• frequency according to the workplace (nature of procedures) – Decree of the Ministry of Health of the Czech Republic No. 440/2000 Coll..
• daily in all areas, in a humid manner
• rooms for invasive procedures (operating theatres) - before the start of the surgical programme and after each patient
• equipment separately allocated for this purpose only, storage in a designated place
• disinfectants in combination with detergents

Treatment of used linen

• put used linen into containers made of impermeable materials
• laundry - program adjusted
• thermo-disinfection (washing at 90 °C for 10 minutes)
• chemodisinfection (washing with disinfectant)
• drying - minimum 140 °C
• ironing - minimum temperature 150 °C
• storage - dedicated areas protected from contamination (mainly aerosols)

Waste management

• is regulated by the Waste Act No. 125/97 Coll.
• specific (category N - hazardous waste)
  • disposal in incinerators with combustion chamber and flue gas cleaning
  • decontamination in approved equipment, then disposal as non-specific waste
• non-specific (municipal and other waste category O - waste not contaminated with pollutants)
  • collect and sort on site into suitable containers - sealable and leak proof
  • disposable syringes and needles - dispose of whole without manual separation, after deterioration place in a rigid plastic container - labelled with place of generation and type of waste
  • medical waste - disposed of daily
  • disposal of amalgam !!! - amalgam separator must be used
    • sedimentation - waste water flows through a multi-chamber vessel with filters made of glass beads or ceramsite (increasing the sedimentation area), efficiency - over 95%
    • centrifugal - in a two-stage system, the heavy amalgam mass is centrifuged and deposited in a collection container, efficiency - 97 %, signalling device (operation, container filling, faults...)
    • dry amalgam waste (surplus, waste after mixing before application), placed in containers with disinfectant solution

Hygienic treatment of tools and instruments

• all instruments intended for manipulation in the oral cavity must be sterile !!!
• when treating, storing and handling instruments in the office
• pre-sterilization preparation – removal of microorganisms that have adhered to objects:
  • disinfection - immersion in a disinfectant with virucidal activity, observing the specified concentration and exposure time
  • mechanical cleaning - water, detergents, soaps, brushes
  • rinsing - under running potable water
  • drying - a place where there is no risk of airborne contamination
  • picking and packing - packing kits and sets, disposable paper, polyamide and combination packaging (+ processor test)
• sterilization
  • most often sterilisation with hot saturated steam under pressure (autoclaves)
  • small capacity sterilizers (Larioclave, Euroclave, Statim, Omega, Instaclave, Faro...)
  • shorter exposure time, lower sterilization temperatures → more dentist-friendly. more gentle on dental instruments
  • modern equipment - post-sterilization drying - sterilization of packaged instruments, printer output - monitoring of sterilization cycles, digital panels - easy control and monitoring of the cycle
• higher degree of disinfection
  • thermolabile devices, devices with optics (cannot be sterilized at high temperatures)
  • decontamination - as pre-sterilization preparation
  • disinfection - immersion of the instrument in a virucidal preparation of a given concentration for a given time, rinsing with sterile distilled water
  • storage in cassettes or other packaging
  • observe aseptic conditions during handling (do not expose to the risk of airborne contamination)
  • products - Sekusept forte, Cidex, Gigasept FF, glutaraldehyde + 0.3% NaHCO3...

Dental instruments and their treatment:

• After use, instruments are immersed in disinfectant tubs and jars with disinfectant solution (usually 2-3%, exposure 30-60 min - depending on the manufacturer).
• Rinsed under running water or mechanically cleaned.
• Re-insert into the disinfectant solution for 15 min.
• Rinse under running water and dry.
• Lubricate the locks of the pliers with oil, sharpen sharp tools, curettes, scalers...
• Wrap them in sterilization bags or cassettes.

The expiration time of instruments in cassettes or tubs is 24 hours, that of instruments stored loose (in a bag) is 6 days. Protected material (in sealed bags) has an expiration time of 12 weeks.

Cleaning of preparation handles:

• immediately after treatment - external disinfection of the end cap
• external cleaning with mule and brush
• disassemble the tip, clean the inside - cleaning and lubricating sprays
• turbines and quick-acting handpieces - after 30 minutes of operation (2-3 times a day)
• normal and reduction handpieces - after 60 min of operation (1 × per day)
• operating test - displacement of excess oil, gradual lowering of the end cap from minimum to maximum operation (5-10 s)
• drills, grinders, root tools
  • after use - 10-15 minutes in undiluted disinfectant solution
  • rinse under running water
  • mechanical cleaning - UZ cleaner, soft brush
  • rinse under running water
  • drying
  • packing in sterilization bags, trays...

Overview

after decontamination

strictly observe civil cleanliness in all operating rooms of the dental facilityclean all rooms once a day with water and disinfectant - sanitary cleaning

wipe equipment and tools with a cloth soaked in disinfectant solution - furniture, chair, unit, at the end and especially at the beginning of the surgery

removable tips – disinfect, clean, sterilise in a suitable way in the apparatus.

non-removable tips - mechanically clean, disinfect

spittoons, sinks, siphons of washbasins to be filled with disinfectant solution or sprinkled with Chloramine or Chlorseptol

clean the unit, chair and adjacent working environment (suction hoses and hoses to the end-pieces) between patients during surgery hours

decontaminate used instruments in two steps (pre-disinfection, mechanical cleaning, rinsing, drying, assembling, or packing in sterilisation containers)

storage of sterile instruments - sealed cassettes, assembly into purpose-made sets sealed in packaging or cassettes

handling of sterile instruments - they are removed from the cassettes only with sterile feeding forceps - in a quiver with disinfectant solution, administered to the attending on a sterile tray covered with sterile pulp

sterile forceps are also used to remove drills, root instruments...

elbows and handpieces (including turbine handpieces) - sterilise in oil sterilisers, change after each use (only surface disinfection is not allowed !!!)

interaction between doctor, nurse and patient - protection of the patient's clothing with disposable paper or washable drape, disposable plastic water cup, doctor and nurse wearing disposable gloves, use of goggles or face shield, hygienic hand washing

sterile protective mask and gloves - procedures that violate the integrity of the skin and mucous membranes, communicating with body cavities

equipment must be individualised for each person

put away instruments immediately after the procedure

interweaving with the ethical principles of the protection and treatment regime

aim - to eliminate or minimise physical and psychological trauma to the patient during medical treatment

Links

References

• ĎULÍKOVÁ, Josefa. Dezinfekce a sterilizace. Urologie pro praxi [online]. 2004, vol. 4, p. 173-174, Available from <http://www.solen.cz/pdfs/uro/2004/04/09.pdf>. ISSN 1803-5299.