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Different Chemical Sterilizations

Surgical equipments

Sterilization is as old as medicine. For ages, man has either consciously or remotely know the relationship between dirt, microbes, infections and decay. The battle against decay and infections has pushed doctors and scientists into developing different sterilization methods geared towards eradicating and keeping off any form of microbes on a surface, custom trays or a substance. The most popular procedure include heat treatment and chemical sterilization.

When is Chemical Sterilization Most Appropriate?

Chemical sterilization comes in when the device in use, or the target substance, is sensitive to heat. This could be rubber or plastic custom trays. Most of the chemical sterilizers are highly reactive low temperature gases or liquid that will either be in direct contact with the target substance or interact with it through a semi-porous membrane or custom strays.

A variety of chemical sterilization procedures exist to cater for sterilant-item compatibility. Choosing the right sterilization chemical will help you avoid contamination or chemical damage to the item you wish to sterilize.

The most common procedures that will work with custom trays in the lab include

  • Ethylene oxide
  • Aldehydes
  • Alcohols
  • Phenols
  • Halogens

Ethylene Oxide Chemical Sterilization

Ethylene oxide is a highly toxic, flammable, reactive gas that is appropriate for custom trays sterilization at relatively low temperatures. It’s high penetration rates gives it the power to seep through different custom trays, for instance thin plastic membranes, making it appropriate for thorough equipment sterilization.

The fact that the gas doesn’t work so well on dried microorganisms limits its use as a general purpose sterilizer. A relative humidity of 40 to 90 percent is necessary to improve efficiency and you must let the sterilized equipment lie for a while to get rid of all the ethylene oxide from the custom trays.


The most popular aldehyde that dominates the custom trays chemical sterilization arena is formaldehyde. This water-soluble gas is easy to deploy using special gas apparatus. It is effective on a wide range of viruses, fungi and bacteria. It will disinfect custom trays and other equipment when dissolved in water while a controlled gaseous discharge can disinfect the air inside rooms.

Direct contact with the skin could result into inflammation or eczemas.

Alcohol Sterilization

Alcohols are a perfect protection against bacteria and fungi. Even though they cannot kill bacteria spores, their rapid action and relatively safe handling makes them the one-touch sterilant of choice during surgical, laboratory or general skin and hand disinfection. The most popular alcohols used in this case are

  • 80 percent ethanol
  • 60 percent propanol
  • 70 percent isopropanol


Phenol, or simply carbolic acid, is a popular protein denaturing sterilization chemical that could work in specific substance sterilization. They are relatively weak and will rarely perform well against spores and viruses. Their moderate effect on organic materials makes them suitable for disinfecting products rather than applying on used equipment and apparatus.


Last on the list of popular chemical sterilization options is chlorine and iodine. These halogens are a popular general microbicidals that are strong enough to kill spores and are rarely use to sterilize custom trays. Chlorine will sterilize and disinfect many things, from water to equipment and surfaces. The less strong iodine often mixes with potassium iodide with alcohol to create tincture of iodine that is used to disinfect skin and small wounds.

Choosing the right chemical disinfectant for the right job will not only ensure total sterilization but also keep the integrity of your equipment and their intended use. The best way to staying on top of this is by understanding how each sterilant works, its strengths and weaknesses from the word go.

Dry heat methods for sterilizing custom tray

Provision of sterile equipment is pivotal in centers where health services are rendered. Ranging from dental clinics to other medical establishments, you can bet on the vitality of such a procedure. In dental clinics, the custom tray must always be sterilized alongside other equipment used. The grave repercussions of using an unsterilized equipment can only be imagined. In other terms, a medical practitioner must always ensure that, before any procedure, the instruments to be used are sterile.

Types of dry heat sterilization

Dry heat sterilization methods are of two types: the static air type and the forced air type.

  • The static air type

This kind of sterilization is commonly referred to as the oven type sterilizer. Here, the heating coils which are found at the bottommost part of the unit initiates the rising of the hot air inside the chamber through gravity convection. This dry heat sterilizer is, however, relatively slow in heating and a consequential longer time for sterilization of the custom tray.

  • Forced air type

Here, the sterilizer has a motor driven blower that circulates hot air throughout the chamber. The hot air is blown at a high velocity which makes it possible to transmit the energy faster form the air to the instrument. Forced air type dry heat sterilization method, unlike its static counterpart, ensures that the hot air is spread uniformly throughout the chamber thus making it more ideal.

Factors essential to achieving sterilization

For sterilization to be attained, there are factors that have to be considered some of which are listed below.

  • Temperature

Heat works to denature proteins in bacteria on the custom tray. Essentially, denaturing involves disrupting the hydrogen bonds and thus leading to the death of the bacteria. When the temperature of the autoclave is tuned higher, it reduces the time it would take to sterilize the custom tray. In the autoclave, the temperature of the saturated steam is in direct proportion to pressure.

  • Time

The fundamental goal of sterilization is to kill all organisms. However, all organisms do not die at the same time. This brings in the time factor in during the process of sterilization. Basically, you have to maintain sterilization conditions inside the autoclave chamber for a time sufficient enough to kill the organisms on the custom tray that take a relatively longer time to die. Otherwise, you’d not be killing all the organisms on the equipment.

  • Air removal

Air insulates the surface of the custom tray being sterilized hence preventing it from effectively being sterilized. So to ensure you have done the process optimally, you must see to it that you remove the air from the surface of the custom tray. Failure to remove it, a contamination spot can form on the surface which can be turn out to be dangerous for the patient who would go through the procedure. There are two methods you can use to remove air from the surface of the custom tray: gravity displacement autoclaves and dynamic air removal method.

So in summary, the methods of dry heat sterilization above are selectively applicable in certain instruments. Additionally, you have to work within the manufacturer’s set conditions lest you cause a malfunction of the sterilizer or destroy the custom tray for instance. Not to forget, the success of sterilization will depend on whether or not you have followed instructions.