This document discusses sterilization protocols for dentistry during the COVID-19 pandemic. It defines sterilization and disinfection, and describes various methods of sterilization including heat, chemicals, filtration, and radiation. It outlines safety protocols for personal protective equipment, patient care, clinical areas, and laboratories. Proper sterilization and disinfection of dental equipment and surfaces is crucial to prevent transmission of the virus.

1. Sterilization protocols in
prosthodontics during Covid-19
pandemic.
Dr. Ashitha Dominic
2nd year PG
Kannur Dental College

2. CONTENTS
• DEFINITION
• METHODS OF STERILISATION
• LEVELS OF DISINFECTION
• BASIC SAFETY PROTOCOLS
Personal care protocol
Patient care protocol
Clinical & operatory protocol
Laboratory protocol
• CONCLUSION
• REFERENCES 2

3. Definitions :
⦁ Sterilisation: It is defined as a process by which an article,
surface or medium is freed of all living micro-organisms
either in vegetative or spore state.
⦁ Disinfection: The destruction or removal of all pathogenic
organisms, or organisms capable of giving rise to infection.
3

4. Methods Of Sterilisation
A. Physical agents
• Sunlight
• Drying
• Dry heat : flaming, incineration, hot air oven
• Moist heat
• Filtration
• Radiation
• Ultrasonic & sonic vibrations
4

5. B. Chemical agents
• Alcohols
• Aldehydes
• Dyes
• Halogens
• Phenols
• Surface active agents
• Metallic salts
• Gases
5
Methods Of Sterilisation

6. Physical agents
⦁ Sunlight: Active germicidal effect due to combined
effect of Ultraviolet rays and heat rays.
⦁ Drying: 4/5th of weight of bacterial cell consist of
water and hence drying has a deleterious effect on
many bacteria.
6

7. ⦁ Heat: The killing effect of heat is due to protein denaturation,
damage by oxidising molecules, destroying cell constituents and
the toxic effect of elevated levels of electrolyte.
Dry Heat
• Flaming: An inoculating loop or wire, the tip of forceps and searing
spatulas can be sterilized by holding them over a Bunsen flame till
they become red hot.
7

8. ⦁ • Incineration: This is an excellent method for terminal sterilization for
destroying biomedical waste.
⦁ • Hot air oven: This is the most widely used method of sterilization by
dry heat. Sterilization is achieved by conduction. The heat is absorbed
by the surface of the item to be sterilized, which then penetrates to
the centre, until the entire item reaches the desired temperature.
8

9. Moist heat
Temperatures below 100 C
⦁ Pasteurization of milk: The milk is heated at either 63°C for 30
minutes or 72°C for 15-20seconds, followed by cooling quickly to 13
°C or lower.
⦁ Inspissation: Media such as LowensteinJensen and Loeffler's serum
are rendered sterile by heating at 80- 85°C for half an hour/on
three successive days in an inspissator.
9

10. ⦁ Temperature at 100°C
⦁ • Boiling: Vegetative bacteria are killed immediately at 90-100°C
but bacterial spores can withstand long periods of boiling. In cases
where boiling is considered adequate, the material should be
immersed in the water and boiled for 10-30 minutes.
⦁ Steam at atmospheric pressure (100°):
⦁ An atmosphere of free steam is used to sterilize culture media
which may decompose if subjected to higher
⦁ temperatures.
⦁ A Koch or Arnold steamer is usually used .
10

11. ⦁ Tyndallisation or Intermittent Sterilisation: It is a method used for
media containing sugars or gelatin. • An exposure to 100°C for 20
minutes on three successive days is used.
⦁ Steam under pressure:
⦁ The equipment used is an autoclave.
⦁ Principle: • The principle of the autoclave
⦁ or steam sterilizer is that when water boils,
⦁ its vapor pressure equals that of the
⦁ surrounding atmosphere.
11

12. Vacuum autoclaves in which air is evacuated from a metal chamber by
vacuum pump are now becoming popular in dentistry.
Gravity displacement autoclaves are small, automatic bench-top
autoclaves. They work on the principle of downward displacement
of air as a consequence of steam entering at the top of the chamber.
12

13. Filtration
Types of filters
⦁ Candle filters are used widely for the purification
⦁ of water for industrial and drinking purposes.
⦁ 1. Unglazed ceramic filters
⦁ 2. Diatomaceous earth filter
⦁ Sintered glass filters
⦁ They have low absorptive property and can be cleaned easily but are brittle
and expensive.
⦁ Membrane filters
⦁ They are made of cellulose esters or other polymers and
⦁ have largely replaced other types of filters.
13

14. ⦁ Radiation
⦁ Two types of radiation are used for sterilization.
⦁ 1. Non ionizing and
⦁ 2. Ionizing.
⦁ Infrared and ultraviolet rays are of the non-ionizing, low-energy type,
while gamma rays and high-energy electrons are the ionizing, high
energy type.
14

15. Recent advances in sterilization
⦁ Plasma sterilization: Plasma is known as the fourth state of matter
and consists of ions, electrons or neutral particles. A radio
frequency energy is applied to create an electromagnetic field.
⦁ Flash sterilization: Flash sterilization was originally
⦁ defined by Underwood and Perkins as sterilization
⦁ of an unwrapped object at 1320°C for 3 minutes at
⦁ 27-28 lbs. of pressure in a gravity displacement
⦁ sterilizer.
⦁ Effects of sterilization on periodontal instruments, JOP, vol 53, no:7, 2011. 15

16. Chemical agents
Aldehydes
Formaldehyde is active against the amino group in the protein
molecule. In aqueous solutions it is markedly bactericidal, sporicidal
and virucidal.
Glutaraldehyde
Has an action similar to that of formaldehyde.
It is especially effective against the tubercle
bacilli, fungi and viruses.
16

17. Alcohols
Ethyl alcohol (ethanol) and isopropyl alcohol
are the most frequently used.
Halogens
Iodine in an aqueous and alcoholic solution has
been widely used as a skin disinfectant.
Phenols
Lysol and cresol are widely used as
disinfectants in hospital.
17

18. Commonly used disinfectants
18

19. Gases
Ethylene oxide: This is a colorless liquid with
a boiling point of 10.7C
and highly penetrating at normal
temperature and pressure.
Formaldehyde gas: • This is employed for
fumigation of operation
theatres and other rooms.
Hydrogen peroxide fogging: Bactericidal
action is by oxidizing the cell wall of the
organism. This has replaced fumigation.
19

20. Surface active agents:They are
widely used as wetting agents,
detergents and emulsifiers.
Metallic salts: Silver, copper and
mercury salts are used as
disinfectants.
20

21. Levels of disinfection
High-level disinfectant: This is a chemical that kills all microbial
pathogens except large numbers of spores.
Eg : glutaraldehyde and hydrogen peroxide.
Intermediate-level disinfectant: A chemical that kills all microbial
pathogens including mycobacteria and non-enveloped viruses
except spores. Eg : alcohol, phenolic compounds and iodophores.
Low-level disinfectant: A chemical that kills only vegetative bacteria,
fungi and lipid enveloped viruses,
Eg : quaternary ammonium compound.
21

22.  Basic safety protocols
Patient care
Personal care
Clinic & operatory care
Laboratory care
22

23. Personal Care protocol
⦁ 1. All asymptomatic treatments/elective procedures should be deferred.
⦁ 2. Proper donning and doffing protocols of PPE(Personal Protective
Equipment.
Gown: Make it mandatory to wear a full cover gown that cover from neck to
knee, arms to end of wrist and wraps on to the back (should be disposable).
Mask : 1. Triple layer surgical mask. 2. N-95 .It is advisable to recheck if the mask
is fitting the face and below the chin snugly and is fastened in the middle of the
head and the neck securely. If there is a respirator attached check the filter’s
patency.
23

24. Goggles and Face Shield: Place it over the face and eye after proper
disinfecting them.
Gloves: Nitrile / Surgical grade gloves should be preferred. Avoid using
the non-sterile “examination gloves “.
Whenever possible two pair of gloves are to be worn, the inner pair
should be of a different color, so as to notice easily any inadvertent tears
on the outer pair of gloves. Glove should be worn so as to extend to
cover the wrist of the gown.
WHO does not recommend using an alcohol based hand sanitizer when
wearing gloves.
24

25. 3. Any treatments generating splatter/aerosol to be done with complete
disposable PPE for all who are operating and assisting. Rubber dam
isolation should be made mandatory.
4. After every splatter related /aerosol generating treatment strict
fumigation is to be done.
5. Water reservoir of the dental chair can be added with 2.5% sodium
hypochlorite or 0.5% hydrogen peroxide.
6. Fees should be encouraged to be paid by Digital routes.
7. Undergo periodic personal health assessment and immediately go
under self-quarantine if developed any symptoms and should inform the
authorities.
25

26. 26

27. Recommendation for PPE in dental
settings
1. Proper selection and use of recommended PPE.
2. Wear gloves whenever there is contact with blood, body fluids, mucous
membranes, non-intact skin or contaminated equipment.
⦁ a. Do not wear the same pair of gloves for the care of more than one
patient.
⦁ b. Do not wash gloves. Gloves cannot be reused.
⦁ c. Perform hand hygiene immediately after removing gloves.
⦁ Use N95 or higher-level respirator during emergency dental care for
patients without COVID-19.
27

28. 3. Wear protective clothing that covers skin
and personal clothing during procedures or
activities where contact with blood, saliva, or
aerosol splatter is anticipated.
4. Reusable eye protection must be cleaned
and disinfected
Disposable eye protection should be
discarded after use.
5. Change gown if it becomes soiled.
28

29. 29

37. Patient care protocol
1. Strict written informed consent, screening
should be procured from all patients
regarding Covid and other diseases in
general. . Meticulous screening of even
asymptomatic patients are important.
2. Keep in mind that the patient may not be
giving a true picture of his/her history or
he/she may be unaware of his/her condition.
All patients must be considered a potential
asymptomatic COVID 19 carrier.

38. 3. Consider recently recovered patients also as a potential virus
carriers for at least 30 days after the recovery confirmation by a
laboratory test.
4. Maintenance of proper record, address, contact details are of
paramount importance.
5. The clinic assistants should also be given proper protective
equipment and should be trained in eliciting patient history as well
as basic checkup preferably using a non-contact thermal scanner.
6. When the patient arrives at the Dental set up, he/she should be
directed to the hand wash station situated outside the main
entrance. It is advisable to have the patient cover his face with a
mask and provided with a Protective gown including foot covers,
before he/ she is taken to the reception.

39. 7 After making the patient scrub their hands using hand
sanitizer or soap, ask them to keep their hands in their
pockets or without touching anywhere till they proceed
to sit on the dental chair.
8 The patient must be made to do a pre-procedural
mouth rinse using Betadine or 1% Hydrogen peroxide/
2% Povidone-Iodine mouth wash for at least 15 seconds
9 Patients should also be covered with a full length
drape with their hands tucked in and a head cap and
goggles and the immediate extra oral area may be
wiped with Betadine solution or a disposable disinfectant
face wipe before commencing the procedure.

40. 10 After the patient gets off the dental chair, the assistant
must ensure that all surfaces with which the patient or
aerosolized particles may have come in contact are
sprayed with surface disinfectant and wiped clean.
11 Encourage minimal follow-up visits.
12 High vacuum extra oral suctions used in conjunction
with high speed saliva ejectors, should be mandatory t0
minimize aerosol dissemination.
13 Intraoral imaging should be restricted and extra oral
radiographs should be utilized to reduce the excessive
salivation and gag reflex associated with intraoral
radiographs.
14 Patients using Removable Prosthesis should be given
additional hygiene recommendations for disinfection of
the prosthesis 40

41. Clinic & operatory protocols
1. All the clinical and auxiliary staff should be
provided proper PPE and should be trained in
sterilization and infection-control protocols.
2.For efficient work flow, a separate screening,
donning and doffing room should be designated.
Donning & doffing should be regularly practiced
as improper donning/doffing will lead to cross-
contamination.
3. It is preferable to work with minimal staff or use
a rotation of your existing staff.
41

42. 4 Hand pieces, burs, diagnostic instruments, etc.,
have to be autoclaved, in sealed pouches. Used
burs should be soaked in a proper disinfectant
solution after scrubbing prior to autoclaving. When
ever possible dispose the burs after single use.
Scrubbing the diagnostic instruments and hand
instruments in a concentrated soap solution for 20
seconds prior to autoclaving may be a good
practice as soap is one of the best antiviral means.
42

43. 5. IMPRESSIONS should be thoroughly disinfected
before pouring or sending to the laboratory as a
standard protocol(Septodent spray, Cidex-
Glutaraldehyde).
Impression compound - 1:10 dilution NaOCl, iodophore
for specfic time,
2% Glutaraldehyde
Alginate -1:10 dilution Sodium Hypochlorite or
iodophors 1:213 synthetic phenols for 10 min
Zinc-oxide eugenol impression paste-2%
Glutaraldehyde or Chlorine compounds
Elastomers impression materials -2% Glutaraldehyde,
0.5%NaOCl for 10 min. There is autoclavable
elastomers but can cause dimensional changes
43

44. Impression disinfection
Dental impressions can give rise to the transmission of
microorganisms and infections.
Clean & rinse the impression
• Cleaning effciency can be improved by gently
scrubbing impression with brush & antimicrobial
detergent
• Sprinkle dental stone on to the impression berfore
rinsing
Spraying/ immersion
• Immersion assures exposure of all surfaces of the
impression.
• After rinsing the impression/tray it is placed in a
bag and liberally spray the entire impression/tray.
• Seal the bag to create charged atmosphere. 44

45. Impression trays disinfection
• Pre-cleaning removes bio-burden &any
adherent impression material
• Ultrasonic cleaning can aid in removing
residual set gypsum
• Cleaning, pack , heat sterilise
• Single use trays to be discarded after
one use
• Custom acrylic trays to be disinfected.
45

46. 6.It is preferable to move to digital dentistry with the use
of Intra oral scanners for digital impressions,
46

47. 7.Minimize use of Air Conditioners and restrict
its use while aerosol generating procedures are
underway. Regular cleaning of its filters should
be done. During fumigation/fogging let the AC
on so as to let the fumigant reach its filters.
8.It is preferable to revamp the HVAC system in
the clinic to suck out contaminate air and push
in fresh air so that the airborne particles may be
shunted out in a clinical environment The clinic
should also be equipped with a superior quality
high vacuum suction and to prevent splatter
preferably and Extraoral suction system .
47

48. ⦁ Cubicle Preparation
⦁ 1. Surface disinfection
⦁ 2. Disinfecting counter tops
⦁ • Any item that cannot be autoclaved should be
⦁ disinfected with a fresh iodophor solution and
⦁ protective cover should be placed.
⦁ • Surfaces can be covered with plastic wrap,
aluminium
⦁ foil or impervious backed absorbent paper.
⦁ • Counter tops should also be disinfected with
⦁ appropriate disinfectants.
48

49. Sterilization & disinfection of patient
care items & devices
⦁ Use single-use devices for one patient only and dispose of
appropriately. Cleaning, disinfection and sterilization of dental
⦁ equipment, Patient-care items (e.g., dental instruments, devices, and
equipment) should be categorized as critical, semicritical, or
noncritical, depending on the potential risk for infection associated
with their intended use. (Spaulding's classification)
49

50. • Critical items, such as surgical instruments and Implant drills periodontal
scalers, are those used to penetrate soft tissue or bone. They have the
greatest risk of transmitting infection and should always be sterilized using
heat.
• Semi-critical items (e.g., mouth mirrors, tooth preparation burs, composite
condensers and plastic instruments, cement carriers , reusable dental
impression trays) are those that come in contact with mucous membranes or
nonintact skin These items have a lower risk of transmission and should also
be sterilized using heat.
• Noncritical patient-care items (e.g., radiograph head/cone, blood pressure
cuff, face-bow) are those that only contact intact skin. These items pose the
least risk of transmission of infection. In the majority of cases, cleaning, or
if visibly soiled, cleaning followed by disinfection with an EPA-registered
hospital disinfectant is adequate.
50

51. ⦁ Dental hand pieces and associated attachments, including low-speed
motors and reusable metallic hand instruments , should always be heat
sterilized between patients. Although these devices are considered
semi-critical, studies have shown that their internal surfaces can
become contaminated with patient materials during use. If these
⦁ devices are not properly cleaned and heat sterilized, the next patient
may be exposed to potentially infectious materials.
51

52. 52

53. 53

54. Laboratory protocols
1. Laboratory personnel should be adorned with
full PPE attire as is worn by the clinical staff.
2. There is evidence to suggest that there is a
risk of transmission of COVID-19 from dental
impressions, casts or dental prosthesis or
appliances. Also the virus can stay active on
various surfaces in the lab including plastic and
cardboard for several hours to few days. So it is
of paramount importance that these should be
thoroughly disinfected prior to handling both at
the clinic or operatory, on acceptance of the
work at the lab and prior to delivery.
54

55. 3.Labs need to use disinfectants containing virucidal
agents that are effective against enveloped viruses. The
active ingredients for these agents can include
Hydrogen peroxide; Sodium hypochlorite; Isopropyl
alcohol among others. The use of soap should be
thought of as an adjunct along with the other agents.
4. In case of spray, sprinkle the product directly on the
surface you are disinfecting. In case of wipe soaked with
disinfectant, it is important to wipe thoroughly the
surface to be disinfected. In both cases it is essential
ensuring that the whole surface to be disinfected has
been covered.. 5.Ensure disinfection of models, casts,
trays, articulators with at least 70 % isopropyl alcohol
based solutions.
55

56. 5.For disinfection of tables/ platforms, floors and sinks
preferably use a sodium hypochlorite based solution.
6.Hands need to be washed thoroughly with soap and
water after every case and avoid touching the face
while in lab. Washing hands is critical to practicing
standard precautions.
7.All technicians or lab personnel need to practice
social distancing in their place of work or seating as
much as possible and maintain a distance of at least 6
feet from each other.
8.While using the trimmers and buff other than using
the PPE see that the flints or fragments are sucked out
using a high vacuum suction.
9.Ensure regular fumigation of the dental laboratory.
56

57. • Prosthodontic items like alocohol torch ,
face bow, articulator, mixing spatulshade
guide can be contaminated by handling
and should be disinfected after each use
• Wax bites & bite registrations - use
iodophore spray disinfection
• Heavy body bite registration materials can
be disinfected by immersion method.
• Dental prosthesis - there is little effect on
chrome-cobalt alloy with short tern
exposures(10min). Do not store in
disinfectant before insertion, Store in
diluted mouthwash.
57

58. • Dental casts - idophor 1.76% for 1 hr, phenol 5%,
NaOCl 0.5%, chloramine T 0.25% can be added to
dental stone while pouring alginate impression
• Lathe - to reduce risk of injury from
aerosols,spatter &macroscopic particles use
protective eye wear, ensure plexiglass shield in
position, activate vaccum.
Pumice has been shown to pose a potential
contamination risk & is mixed with diluted 1:10bleach
or tincture of green or soap
58

59. Conclusion
⦁ All the activities are designed to accomplish one goal -
break the link in the chain of infection. Dental office and
labs should work closely together to co-ordinate control
of potential cross infection between people. the control
of infectious disease in prosthodontics is not difficult
and protecting himself is the major concern
59

60. “
References
• Ananthanarayan And Panikers. Textbook Of Microbiology. 10th Edition. India: Universal
Press; 2016.
• Rani L. Sterilization Protocols In Dentistry-a Review. Journal Of Pharmaceutical Sciences
And Research. 2016 Jun 1;8(6):558.
• Sreekumar S, Varghese K, Abraham JP, Jaysa JJ. An in vitro evaluation of the efficiency
of various disinfection and sterilization methods to decontaminate dental handpieces. J
Dent Res Rev 2018;5:50-3.
• Webinar on mangement of impression materials models in covid19 era; Dr veena jain, dci
webinar.
• IPS protocols in management of covid 19 pandemic
60