Question

Chemical methods of sterilization in periodontology

Answer 1

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Chemical sterilization has been used as a reliable method, but it presents its own set of challenges. The major concerns are (1) the possibility that the sterilant will react with the polymer material being sterilized; (2) the toxic effect of residual chemicals left on the product; and (3) operator safety associated with the exposure to a sterilant.

Ethylene oxide (EO) sterilization

While chemical methods, such as EO, have proven to be effective at much lower temperatures than thermal sterilization, there is a concern that a certain level of humidity is required to work in concert with the gas to achieve the desired SAL. This is a disadvantage of this method because, for absorbable polymers, moisture can accelerate chain degradation and adversely affect the mechanical properties of the material. Another disadvantage is that EO is known to be a carcinogen and highly explosive, which introduces many safety concerns for operators. In addition, the gas can react with the polymer being sterilized. Incomplete removal of EO and hence residual gas and its reaction by-products (such as ethylene chlorohydrin) in implanted materials are of great concern. Accordingly, extra time is required for aeration of the materials to ensure that the residual amounts are brought down to safe levels. It is also worth noting that EO is essentially a surface sterilant and its diffusion into the bulk of a device is limited. Penetration depends on the amount of surface area that needs to be exposed to the gas and the path that the gas needs to take to reach all areas of the device. For example, it ismore difficult to sterilize the inside of a long narrow tube than it is to sterilize the outside surface of a device.