OBJECTIVEThe purpose was to analyze the effects of three sterilization methods (dry heat sterilization, steam sterilization, chemical sterilization) on the corrosion of dental fissure burs.

METHODS100 dental fissure burs were distributed to 10 groups. One was control, the burs in the other 9 groups were treated by dry heat sterilization, steam sterilization, chemical sterilization with 5, 10, 15 cycles respectively. Weight method, scanning electron microscope, micro-hardness measurement were used to analyze the corrosion of dental fissure burs.

RESULTSThe fissure burs gained their weight with cycles of sterilization. 5, 10, 15 cycles of dry heat sterilization, 10, 15 cycles of steam sterilization and 15 cycles of chemical sterilization, the weight of fissure burs were significantly increased (P < 0.05). Scanning electron microscope showed differences on the surfaces of dental fissure burs among the three sterilization groups. After sterilization, spot or partial erosion were seen on the surface of the burs. The steam sterilization groups showed the most evident changes, followed by chemical sterilization groups and dry heat sterilization groups. X-ray energy spectrometer showed the steam sterilization groups had the largest percentage of W, followed by dry heat sterilization groups, chemical sterilization groups and control group. Fe had the opposite trends. Micro-hardness reduced after sterilization. The reduction was most clear in steam sterilization group, followed by chemical sterilization and dry heat sterilization ( P< 0.05). The difference between 5 and 10 times of steam sterilization and 5, 10, 15 times of chemical sterilization were significant difference (P < 0.05). There was no significant difference between 5, 10, 15 times of dry heat sterilization (P > 0.05).

CONCLUSIONThe corrosion is most severe in steamsterilization group, followed by chemical sterilization, dry heat sterilization. Dry heat sterilization shows less corrosion.