Failure of ethylene oxide to sterilize extracted human teeth

Objectives. The purpose of this study was to determine if ethylene oxide could sterilize extracted human teeth to be used in research. Methods. An occlusal preparation was cut in freshly extracted molars, and a small hole was drilled into the pulp chamber. A suspension of Bacillus subtilis (globigii) endospores, the standard biological monitor used for ethylene oxide sterilization, was injected into the pulp cavity, and the pulp cavity access was filled with composite material and sealed with a light-cured sealant. The teeth were exposed to either a 30°C or 63°C ethylene oxide sterilization process. Following exposure, the teeth were aseptically split and cultured to reveal viable spores. Results. Sixty-four percent of the teeth exposed to “cold” ethylene oxide treatment and 80% of the teeth exposed to the “warm” treatment still contained viable spores. Significance. Ethylene oxide cannot be relied on to sterilize extracted human teeth. Therefore, before they are used in research, other methods should be used to ensure killing of bloodborne pathogens that may be present within the teeth.