Sterilisation And Infection Control Question And Answers

Sterilisation And Infection Control Important Notes

1. Critical items

  • Includes instruments that contact tissues or penetrate tissues
  • Usually, there are disposable or single-use items
  • Example: scalpels, blades, endodontic files, syringes, etc

2. Semi-critical items

  • Items that are handled by gloved hands coated with blood and saliva or that may touch mucosa
  • These can be either disposable or they can be cleared, sterilized or disinfected
  • Example:  air water syringe tip, suction tips, prophy angle, handpiece

3. Noncritical items

  • These are environmental surfaces such as chairs, benches, floors, walls, and supporting equipment
  • They are not ordinarily touched during treatment
  • These surfaces can be cleaned, disinfected, and covered

Sterilisation And Infection Control Long Essays

Question 1. Discuss various methods of sterilization.


Various methods of sterilization:


It is defined as the process by which an article, surface, or medium is freed of all living organisms either in a vegetative/spore state. Its method is.

Conservation And Operative Dentistry Sterilisation And Infection Control Sterilisation


1. Presoaking:

  • Prevent drying of blood, saliva, and debris
  • Facilitate cleaning

2. Cleaning:

  • Remove blood and saliva


  1. Manual – Use of nylon brushes + detergents
  2. Ultrasonic – Provide fast and thorough cleaning
  3. Enzyme cleaning – Has specific catalytic behavior

3. Packaging:

  • Protects instruments from contamination after sterilization and before use


  1. Self-sealing
  2. Paper plastic
  3. Peel pouches
  • Sterilization
  • Monitoring of sterilization
  • Handling of processed instruments

Sterilization of Different Instruments:

Conservation And Operative Dentistry Sterilisation And Infection Control Sterilisation of Different instruments

Question 2. Infection Control.



Immunization: Vaccination recommended for Hepatitis B for all dental personnel

Personal Barrier

1 Handwashing:

Sterilisation And Infection Control

2. Gloves:

  • Protects against contamination
  • Changed between patients and for the same patient if it is worn/torn


  1. Surgical
  2. Latex
  3. Vinyl
  4. Double gloves for HBV and HIV [Hepatitis B Virus and Human Immunodeficiency Virus]

1. Face masks:

  • Protects from inhalation of aerosols
  • Prevents spatter from patient’s mouth
  • Prevents splashes of contaminated solution
  • Changed once per hour/between patients/whenever it becomes moist

2. Protective clothing:

  • Reusable/disposable gowns with long sleeves, high neck, and long knee length

3. Eyewear:

  • Prevention against Hepatitis B
  • Prevent bacterial/viral contact

Surgical Asepsis:

  • Preparation of surgical site
  • Draping the patient

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

  • Isolation

Surface Asepsis:

  • Sterilization of instruments
  • Use of disposable instruments
  • Wrapping with aluminum foil or applying disinfectant to things that are often touched during treatment such as dental light, chair

Disposable of waste:

  • Methods:
    • Incineration
    • Burial in a landfill
    • Discharge of liquid to a sewer
    • Sterilization

Sterilization And Infection Control Short Essays

Question 1. Hot Air Oven.


Hot Air Oven:


1. Chamber with double wall

  • Inner-copper plate
  • Outer – Asbestos

2. Adjustable holes – Monitor time and temperature

3. Thermostat – Regulate temperature

Time And Temperature:

  • 160°C – 1 hour
  • 180°C – Vz hour

Instruments That Can Be Sterilized:

  • Glassware, forceps, scissors, scalpels, swabs


  • Fitted for even distribution of air
  • Not overloaded
  • Arranged to allow free circulation
  • Cooled for 2 hours before opening the door.

Question 2. Autoclave.




  • Water boils when its vapor pressure equals that of the surrounding atmosphere
  • Steam is produced
  • It condenses to water as it contacts the surface and transfers its latent heat to it.

Time And Temperature:

  • 121°C – 15 minutes at 15 lbs pressure
  • 136°C – 3 minutes at 30 lbs pressure

Articles That Can Be Sterilized

  • Culture media, saline, syringes, needles, dressings, gloves, aprons, gowns


  • Rapid
  • Effective
  • Good penetration

Question 3. Glass bead sterilization.


Glass bead sterilization:

  • A rapid method of sterilization
  • Salt used: 1% sodium silico-aluminate, sodium carbonate, or magnesium carbonate
  • Salt is replaced by glass beads provided the beads are smaller than 1 mm in diameter as larger beads enable to transfer of heat to the endodontic instrument
  • Time: 5-15 seconds, Temperature – 437 – 465°F


  • The handle portion is not sterilized


  • Economic
  • Salt does not clog the root canal

Sterilisation And Infection Control Short Answers

Question 1. Autoclave



Autoclave is the process of sterilization by saturated steam under high pressure above 100 degrees C temperature

Sterilization Conditions:

Conservation And Operative Dentistry Sterilisation And Infection Control Sterilisation Conditions


  • Articles sterilised in autoclave are:
  • Culture media
  • Rubber articles like tubes, gloves, etc
  • Syringes and surgical instruments
  • OT gowns, dressing materials
  • Endodontic instruments
  • Hand instruments

Question 2. Contour.



  • Buccal and lingual surfaces of teeth possess some degree of convexity
  • Facilitate seepage of food
  • Present over cervical third on facial surfaces of all the teeth, lingual surfaces of incisors, and canines.
  • Middle third – On lingual surfaces of posteriors


1. Normal contour

  • Shunt food toward the buccal vestibule
  • Stimulate intervening tissues

2. Over contour

  • Plaque accumulation
  • Interferes with self-cleaning action

3. Under contour

  • Opening of embrasure
  • Affect the gingival

Conservation And Operative Dentistry Sterilisation And Infection Control Buccal and lingual curvatures

Question 3. Contacts.




  • Broad contact faciolingually
    • Prevents seepage of food
  • Broad contact occlusogingivally
    • Sticky food is held
    • Irritates gingiva
  • Contact located apically
    • Packing of sticky food
    • Impinges tissue
  • Contact located initially
    • Predisposes to proximal caries
    • Prevents food being pushed into embrasures
  • Contact located buccally
  • Loose contact
    • Food lodgement
    • Gingival problems
    • Caries

Question 5. Embrasures.



  • V-shaped spaces originating at the proximal contact area between adjacent teeth
  • Types – Facial, lingual, incisal/occlusal and gingival


  • Serve as spillways for the escape of food
  • Prevents forcing the food into the contact area

Sterilisation And Infection Control Viva Voce

  1. Disinfectants containing 70-90% ethyl alcohol are considered the most effective disinfectants on cleaned surfaces
  2. Sterilants used for high-level disinfection of items for reuse are glutaraldehydes at 2-3 % concentrations
  3. Sterilization must be tested routinely
  4. Autoclave is done at 121°C temperature for 15 min at 15 lb pressure
  5. Chemiclave is done at 131°C for 30 min at 20 lb pres-sure
  6. Too little contour may result in trauma to the attachment apparatus
  7. Improper contact can result in food impaction between teeth
  8. When embrasures are decreased in size, additional stress is created on teeth
  9. Lingual embrasures are usually larger than facial embrasures

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