Sterilization 2

Uses of  Flash sterilization:

it is for processing cleaned patient-care items that can not be packaged and stored before use. it also use when there is no time to sterilize an item by the preferred package methods.

Low-Temperature Sterilization Technologies

Low-temperature sterilization technologies are used instead of steam for sterilizing heat-sensitive or moisture-intolerant surgical equipment and supplies.

Hydrogen Peroxide Gas Plasma

new sterilization technology based on plasma was patented in 1987. gas plasmas have been referred to as the fourth state of matter(liquids,solids,gases,gas plasmas) gas plasmas are generated in an enclose chamber under deep vacuum using radio frequency or microwave energy to excite the gas molecules and produce charged particles many of which are in the form of free radicals, it's a highly reactive species and thereby disrupt the metabolism of microrganisms

Cleaning the dental chair and instrument

You must wear masks and gloves

use dental cleanser

clean the dental chair

use dental cleanser

suck the cleanser

wash out the dental instrument

brush the dental instrument

put instrument into the disinfectant

dry the dental instrument

put instrument into the sterilization pouch 

    wash your hands~~~ finish

                                                             

Factors affecting the efficacy of disinfection and sterilization

Factors:

1.Number and location of microorganisms
2.Innate resistance of microorganisms
3.Concentration and Potency of disinfectants 
4.Physical and Chemical factors
5.Organic and Inorganic matter
6.Duration of exposure
7.Biofilms


Number and location of microorganisms:
all others condition remaining constant, the larger number of microbes need more time to elimination all of them, because this reason, people need to scrupulous cleaning of medical instruments before disinfection and sterilization. It can reduce many microorganisms on the instruments. increases the margin of safety when the germicide is used according to the labeling and shortens the exposure time required to kill the entire microbial load. 

Innate resistance of microorganisms:
microorganisms vary greatly in their resistance to chemical germicides and sterilization processes, intrinsic resistance mechanisms in microorganisms to disinfectants vary. the user needs to employ exposure times and a concentration of germicide needed to achieve complete destruction.

Concentration and Potency of disinfectants:
with other variables constant, high concentrated has the greater efficacy and the shorter time necessary to achieve microbial kill than the low concentrated.Considering the length of the disinfection time, which depends on the potency of the germicide,also is important. This was illustrated by Spaulding who demonstrated using the mucin-loop test that 70 percent isopropyl alcohol destroyed 10000 M.tuberculosis in 5 mins,whereas a simultaneous test with 3 percent phenolic required 2-3 hours to achieve the same level of microbial kill.

Physical and Chemical factors:
several physical and chemical factors also influence disinfectant procedures:temperature,PH,relative humidity,and water hardness.

Organic and Inorganic matter:
Organic matter in the form of serum, blood, pus, or fecal or lubricant material can interfere with the antimicrobial activity of disinfectants.The effects of inorganic contaminants on the sterilization process were studied during the 1950s and 1960s.　These and other studies show the protection by inorganic contaminants of microorganisms to all sterilization processes results from occlusion in salt crystals, so the cleaning before sterilization and disinfection is very important. organic and inorganic matter are very easy to remove by washing.

Duration exposure:
items must be exposed to the germicide for the appropriate minimum contact time.

Biofilms:
Microorganisms may be protected from disinfectants by production of thick masses of cells and extracellular materials, or biofilms.

Approach to Disinfection and Sterilization

Why is this topic necessary?

because disinfection and sterilization are similar, but there still some important different between them. so people need to know what is the different between them and their different definition and application...
disinfection and sterilization are both decontamination processes. disinfection is the process that kill most of the disease producing microorganisms, and sterilization is the process of killing "all" the microorganisms. this is the main different between sterilization and disinfection, and there are others different between  them. like methods, types, application.

Methods:

disinfection use phenolic disinfectants, heavy metals, halogens, bleach, alcohols, hydrogen peroxide, detergents, heating and pasteurization.

sterilization use heat, chemicals, irradiation, high pressure, and filtration.

Application:

Disinfection is used mostly to decontaminate surfaces and air.

Sterilization is used for food, medicine and surgical instruments.

Spaulding Classification

Critical items: Itmes that used in surgery, which pierce oft and hard tissue-scalpel blades,burs,extraction forceps,elevator,needles,files,bone-rongers,periodontal instrument used in prophylaxis,surgical drains for abscesses, and other instrument used in surgery,dental explorers,periodontal probes,biopsy punch,surgical drains,endodontic files and reamers, and implants

Semicritical items:items that do not necessarily penetrate soft and hard tissues but which cross the vemilion border into the oral cavity-mouth mirrors,handpiece,anesthetic syringes,chip syringes,amalgam condensers,impression trays,air/water syringe tips,high-volume evacuator tips

Non critical items:items used in dentistry,which do not cross the vemilion border or penetrate the soft tissues-chair light handles,instrument trays,high touch work surfaces,bracket tables,chair controls,air/water syringes,hoses and dental chairs

sterilization

Definition of sterilization:

1.the act of sterilizing 2.the condition of being sterilized 3.elimination of all living microorganisms.

Steam sterilization basic principle:

six factors are particularly critical to assure successful steam sterilization 1.Time: every microorganisms the exposure time to kill them are different, a minimum amount of time at sterilization temperature is required to kill all the organisms.
2.Temperature: the second critical factor in steam sterilization is the temperature of the saturated steam controlled in the chamber of the sterilizer,this chart illustrates approximately how much time is required to achieve equivalent microbial lethality at different moist heat exposure temperatures you can clearly demonstrates how increasing the temperature dramatically reduces the time needed to achieve sterilization



















3.Moisture: moisture in the steam has a major impact on its ability to denature, or coagulate proteins: hence the importance of using saturated steam. saturated steam is at equilibrium with heated water at the same pressure, which means it contains the maximum amount of moisture without liquid condensate present. saturated steam is recommended for steam sterilization. 4.Direct Steam Contact:direct steam contact with the surface of the object to be sterilized is required for the steam to transfer its stored energy to the object. without direct stem contact to all surfaces, the item will not be sterilized. the amount of energy stored in steam is much higher than dry air or water at the same temperature. 5.Air Removal: air is the biggest deterrent to steam sterilization. air must be removed from the chamber and the load before direct steam contact and sterilization can occur. this is accom-phlished in a steam sterilizer by a series of vacuum pulses prior to sterilization. a small amount of air will always be present in the autoclave chamber, but must be minimized. insufficient air removal, sterilizer chamber vacuum leaks and poor steam quality are the most common causes of sterilization failures. 6.Drying:items must be dry before they removed from the sterilizer,condensation is the natural result of steam ontact with the coller surfaces of the load during the heating and exposure phases. the presence of condensation can cause re-con-tamination of the load when removed from the sterilizer. A steam sterilizer dries the load after sterilization by drawing a deep vacuum in the chamber