Modern times have introduced new technology into the medical world as well as fear in the public. Never before have people been so concerned about spreading diseases or even the common cold to others, and this has made the sterilizer industry invaluable. Additionally, sterilizers are a cost-effective sterilization method for industries that would rather disinfect equipment and reuse it than to constantly purchase new equipment.
There are many types of sterilizers, but the two most common are the dry heat sterilizer and the steam sterilizer autoclave. Dry heat sterilizers use very high temperatures to kill microorganisms. To effectively kill spores, dry heat sterilizers must reach 170 degrees Celsius and remain at that temperature for one hour. This type of sterilizer is particularly useful when sanitizing metal instruments because it does not rust the equipment nor dull metal edges.
Steam sterilizers, or autoclaves, like dry heat sterilizers use very high temperatures to destroy harmful microorganisms, but they also use pressure over a specific amount of time to disinfect. Contrarily, autoclaves must only reach about 121 degrees Celsius for fifteen minutes to sterilize. They are the most popular sterilizer choice because they can be used with a variety of equipment; however, the steam may damage unprotected instruments. This damage can cause corrosion or dullness to the equipment. Consequently, thorough drying after the steam exposure is very important; otherwise dampness could invite these dangerous organisms to penetrate the very items you are trying to clean.
What is Autoclave (Sterilization by Steam)?
Sterilization is the destruction of all forms of microbial life, as verified by demonstrating the killing of highly resistant bacterial spores. It is the highest level of microbial kill. Sterilization by steam or autoclaving is one of the most common and widely used methods for sterilization in dental practices. The process refers to a process of instrument sterilization that uses time, temperature and pressure to kill all forms of microbial life, including spores. An autoclave is a pressure chamber, kind of a vessel that uses high-pressure steam to sterilize equipment and supplies. This is believed to be one of the most efficient methods of sterilization, destroying all microorganisms, both pathogenic and non-pathogenic, including spores and viruses. Autoclaving requires a minimum of 121 degrees celsius (250 degree Fahrenheit) with steam pressure of 15 pounds per square inch (psi), for 15 minutes to ensure sterilization.
What are the Advantages of Moist Heat Sterilization?
- Take less time to sterilize
- Require low temperature
- Easy to monitor and control
- Low cost and non-toxic
What are the Disadvantages of Moist Heat Sterilization?
- Cannot sterilize the heat-sensitive instrument
- Lead to corrosion after sterilization
- Repeated exposure of instrument can lead to damage
What is Dry Heat Sterilization?
Dry heat sterilization is yet another popular method for sterilization that uses time and heat to kill all forms of microbial life, including microbial spores and viruses. This process is basically sterilizing using an oven. Dry-heat ovens are used to sterilize items that may corrode in the steam autoclave. The unit requires maintenance and does not corrode or rust instruments and equipment. The amount of time necessary to sterilize depends on the temperature of the oven. Dry heat sterilization usually takes about an hour or so at 340 degrees Fahrenheit or 2 hours at 320 degrees Fahrenheit. It must only be used for items that are damaged by, or are impenetrable to, moist heat. The only downside to dry heat sterilization is that it is relatively slower than autoclaving.
What Are the Advantages of Dry Heat Sterilization?
- Tend to be non-toxic and reliable
- Low cost and easy to install
- No chances of corrosion
- Tend to be eco-friendly
- It penetrates materials effectively
What Are the Disadvantages of Dry Heat Sterilization?
- Takes more time for sterilization
- Exposing the instrument to a higher temperature is dangerous
- Require extremely high temperature
Difference between Autoclave and Dry Heat Sterilizer
Sterilization by steam is carried out by a specialized pressure-induced chamber called an autoclave that uses high-pressure steam to sterilize equipment and supplies. It is one of the most common and the oldest methods for sterilization of instruments and materials, mostly used in dental offices. Autoclaves are available in various sizes and types. Another popular method used for sterilization in the dental offices is through dry heat. One of the simplest methods of dry heat sterilization is direct flaming. Although, dry heat sterilization is relatively slower than autoclave processing, it is good for instruments that tend to rust in a moist autoclave. Let’s take a look at the two sterilization processes in detail.
Method of Autoclave and Dry Heat Sterilizer
While autoclaving and dry heat sterilization are two of the commonly used methods of sterilization in dental practices, autoclaving is one of the most common and the oldest methods for sterilization of instruments and materials used mostly in hospitals. Autoclaving refers to a process of instrument sterilization that uses time, temperature and pressure to kill all forms of microbial life, whereas dry heat sterilization is basically sterilizing using an oven that uses time and heat to kill all forms of microbial life, including microbial spores and viruses.
To ensure sterilization, the pressure chamber or the autoclave is required to increase the saturation steam temperature to minimum of 121 °C or 250 °F with steam pressure at 15-16 pounds per square inch (PSIG) for 15 to 30 minutes. It is important to follow the directions specific to the autoclave with which you’re working. Dry heat sterilization usually takes about an hour or so at 340 °F or 2 hours at 320 °F. The instruments must be dry before sterilization and the door should not be opened until the entire cycle is completed.
Applications of Autoclave vs. Dry Heat Sterilizer
Sterilization by steam can be used for all items that can accept heat and moisture but steam can penetrate dense materials such as containers, wraps, PVC tubing, etc. Steam can also damage plastic and rubber items. They are also used to decontaminate biological wastes. Although, dry heat sterilization is relatively slower than autoclaving, it is widely used to sterilize materials that may be damaged by moisture or are impenetrable by steam. They are used to remove pyrogens from glassware, most commonly in the pharmaceutical industry. However, dry heat should never be used on soft rubber goods.
Frequently Asked Questions
- Is Moist Heat Better Than Dry Heat?
Moist heat sterilization penetrates deeper into the tissues making it more effective than dry heat sterilization. It also takes a shorter period than dry heat.
- When Should You Use Moist Heat?
Immediately after exercises. Research shows that moist heat immediately after exercise was more effective than dry heat just after exercise.
- Why Is Dry Heat Bad For Muscles?
They leave the skin dehydrated. This happens so since dry heat like electric heating pads and saunas draw moisture from the body.
- What Does Moist Heat Do For Muscles?
Aid in the heat penetration into the muscles. Hence, some people feel that moist heat provides better pain relief.
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