Sterilization
Question.1. Write briefly on sterilization.
Or
Write short note on sterilization in surgery.
Or
Write short note on sterilization.
Answer. Sterilization is the complete removal of all types of microbes. It can be attempted by one of the following methods of sterilization.
1. Heat method: Dry heat or moist heat
2. Ionizing radiation
3. Ethylene oxide gas.
Sterilization Heat Method
- Dry heat: The most common apparatus, which works on the principles of dry heat, is hot air oven.
- The hot air oven, which has controlled cycles,160°C for one hour are suitable for killing bacteria on materials, which are not penetrated by steam.
- Dry heat oxidize the bacterial cytoplasm, e.g. glassware, oils, petroleum jelly.
Read And Learn More: General Surgery Question And Answers
- Moist heat: Steam kills bacteria by coagulating cytoplasm and is an extremely effient sterilizer when used under increased pressure when the temperature exceeds 100°.
- Autoclave is the apparatus used which causes sterilization by moist heat within 30 min.
- The autoclave work at temperature of 121°C at 15 Ibs pressure per square inch for 15 to 20 minutes.
Sterilization Ionizing Radiation
Gamma rays are lethal, non-charged, ultrashort, wavelength rays with great penetrating power from a radioactive isotope such as cobalt-60, disposable plastic syringes, sutures and rubber glass are examples.
Sterilization Ethylene Oxide Gas
- It is a highly toxic inflammable gas, which kills all types of microbes including bacterial spores.
- CO2 is mixed with ethylene oxide gas to reduce likelihood of explosion.
- The gas diffuses well through items such as plastic materials, swab,s and paper.
Question.2. Discuss the asepsis and antiseptic measures in orodental surgery patients.
Answer. Asepsis means precautions taken before any surgical procedure against development of infection.
Antisepsis means all surgical procedures done after taking precautions.
- The concept of asepsis can be applied in any clinical setting.
- The element requiring careful attention is equipment or supplies. Medical and dental equipment can be sterilized by chemical treatment, radiation, gas, or heat.
- Personnel can take steps to ensure sterility by assessing that sterile packages are dry and intact and checking sterility indicators such as dates or colored tape that changes color when sterile.
- Besides overall attention to the clinical environment and equipment, clinicians need to be attentive to their own practices and those of their peers in order to avoid inadvertent contamination.
- Aseptic technique is most strictly applied in the operating room because of the direct and often extensive disruption of skin and underlying tissue.
Aseptic technique helps to prevent or minimize postoperative infection.
- The patient is prepared or prepped by shaving hair from the surgical site, cleansing with a disinfectant such as iodine, and applying sterile drapes.
- In all clinical settings, handwashing is an important step in asepsis.
- In general settngs, hands are to be washed when visibly soiled, before and after contact with the patient, after contact with other potential sources of microorganisms, before invasive procedures, and after removal of gloves.
- Patients and visitors should also be encouraged to wash their hands. Proper handwashing for most clinical settngs involves removal of jewelry, avoidance of clothing contact with the sink, and a minimum of 10–15 seconds scrubbing hands with soap, warm water, and vigorous friction.
A surgical scrub requires use of a long-acting, powerful, antimicrobial soap, careful scrubbing of the fingernails, and a longer period of time for scrubbing.
- Institutional policy usually designates an acceptable minimum length of time required.
- Thorough drying is essential, as moist surfaces invite the presence of pathogens.
- Contact after handwashing with the faucet or other potential contaminants should be avoided.
- The faucet can be turned of with a dry paper towel, or, in many cases,through use of foot pedals.
- Despite this careful scrub,bare hands are always considered potential sources of infection.
- An important principle of the aseptic technique is that fluid (a potential mode of pathogen transmission) flies in the direction of gravity.
With this in mind, hands are held below elbows during the surgical scrub and above elbows following the surgical scrub.
- Sterile surgical clothing or protective devices such as gloves, facemasks, goggles, and transparent eye/face shields serve as a barrier against microorganisms and are donned to maintain asepsis in the operating room.
- This practice includes covering facial hair, tucking hair out of sight, and removing jewelry or other dangling objects that may harbor unwanted organisms.
- This garb must be done with deliberate care to avoid touching external, sterile surfaces with nonsterile objects including the skin.
- This ensures that potentially contaminated items such as hands and clothing remain behind protective barriers, thus prohibiting inadvertent entry of microorganisms into sterile areas.
- Personnel assist the surgeon to wear gloves and garb and arrange equipment to minimize the risk of contamination.
Donning sterile gloves requires specifi technique so that the outer glove is not touched by the hand.
- A large cuf exposing the inner glove is created so that the glove may be grasped during donning.
- It is essential to avoid touching nonsterile items once sterile gloves are applied;the hands may be kept interlaced to avoid inadvertent contamination.
- Any break in the glove or touching the glove to a nonsterile surface requires immediate removal and application of new gloves.
- Asepsis in the operating room or for other invasive procedures is also maintained by creating sterile surgical fields with drapes.
- Sterile drapes are sterilized linens placed on the patient or around the field to delineate sterile areas.
- Drapes or wrapped kits of equipment are opened in such a way that the contents do not touch nonsterile items or surfaces.
Aspects of this method include opening the furthest areas of a package fist, avoiding leaning over the contents, and preventing opened flops from falling back onto contents.
Other principles that are applied to maintain asepsis include:
- All items in a sterile field must be sterile.
- Sterile packages or fields are opened or created as close as possible to time of actual use.
- Moist areas are not considered sterile.
- Contaminated items must be removed immediately from the sterile field.
- Only areas that can be seen by the clinician are considered sterile, i.e. the back of the clinician is not sterile.
- Gowns are considered sterile only in the front, from chest to waist and from the hands to slightly above the elbow.
- Tables are considered sterile only at or above the level of the table.
- Nonsterile items should not cross above a sterile field.
- There should be no talking, laughing, coughing, or sneezing across a sterile field.
- Personnel with colds should avoid working while ill or apply a double mask.
- Edges of sterile areas or fields (generally the outer inch) are not considered sterile.
- When in doubt about sterility, discard the potentially contaminated item and begin again.
- A safe space or margin of safety is maintained between sterile and nonsterile objects and areas.
- When pouring flids, only the lip and inner cap of the pouring container is considered sterile.
The pouring container should not touch the receiving container, and splashing should be avoided. - Tears in barriers are considered breaks in sterility.
Question.3. Write short note on autoclave.
Answer. It is the means of moist heat sterilization.
- It is the method of choice for sterilization of instruments as it eliminates even resistant spore-forming microorganisms, fungi, viruses along with vegetative microorganisms.
- It works on principle of steam under pressure.
- It has two pressure cycles i.e.
- 15 psi pressure at 121°C for 30 minutes.
- 30 psi pressure at 134°C for 3 to 5 minutes also known as Flash method.
Autoclave Mechanism of action
Steam is the mixture of heat and water vapor.
As it comes in contact with any cool surface it get condensed and heat is released from water.
This heat is taken by surface it comes in contact with. Heat goes on penetrating deeper layers of object.
Steam and air move in vertical direction and the movement is quicker penetration of steam into the material, it is also better if articles are placed vertically in autoclave.
Autoclave Advantages
- It is economical.
- Penetration is good.
- Cycle time is short.
- It is monitored easily.
- No exhaust or special chemicals are to be required.
Autoclave Disadvantages
- Carbon steel gets damaged.
- Moisture retention is present.
Question.4. Write short note on methods of sterilization of dental instruments.
Answer. Following are the methods for sterilization of a dental instrument:
- Placing the instrument presoaking solutions, i.e.phenolic compounds prevents drying of debris and also helps in microbial killing.
- Autoclaving is the most accepted method of sterilization of surgical instruments as it eliminates bacteria, viruses, fungi, and spores.
It works on the principle of steam under pressure of 15 lb at l2l°C for 20 min or 30 lb at l34°C for 3 minutes.
It has excellent penetration, facilitating exposure of all instrument surfaces to the steam. - Dry heat ovens or the unsaturated chemical vapor sterilizers are the other means of sterilization.
Hot air ovens require 160°C and 2 hours for sterilization - Ultraviolet light may kill microorganisms that are directly exposed to the light; however, the light may not reach all the surface of an instrument. A temperature of l60°C–l70°C maintained for l hour is capable of sterilization.
- Glass bead sterilizers are used to sterilize endodontic files and burs in beads. They require 10 seconds for sterilization.
Question.5. Write briefly on chemical sterilization.
Answer. Chemical sterilization is also known as cold sterilization.
Following are the various chemicals used in chemical sterilization:
Question.6. Write difference between sterilization and disinfection.
Answer.
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