Effect of repeated sterilization and ultrasonic cleaning on curet blades

Instrument cleaning and sterilization are important steps in infection control. This study investigated the effect of repeated ultrasonic cleaning, cycles of autoclave or chemiclave, on the surface and cutting edge of stainless steel and carbon steel curets.

Eight carbon steel and six stainless steel Columbia #13/14 curets were cleaned or sterilized in a series of treatments by one of the following methods: ultrasonic cleaning, chemiclave sterilization, and autoclave sterilization. In addition, two carbon steel instruments were placed in an anticorrosive dip followed by autoclave. The blades of the curets were examined and photographed with the scanning electron microscope (SEM) at 200 X and 1000 X for baseline and after 2, 4, 8, 16, and 32 treatment cycles. Photographs were evaluated for visible change in surface appearance by four examiners independently. Photographs for each treatment time were compared to the baseline (pretreatment) photographs for the same instrument. They were scored as (1) no visible change; (2) slight change; or (3) moderate to major change. Changes observed were: surface pitting, corrosion products as additions to the surface, edge deterioration, or loss of structure.

Stainless steel curets showed slight or no change after the three treatments. Carbon steel curets were affected by all treatments. The chemiclave produced slight change. The autoclave produced slight change after the fourth treatment cycle and moderate to major change after the eighth cycle. Those carbon steel instruments treated by anticorrosive dip followed by the autoclave showed pronounced change after 16 or 32 cycles. The most varied results were from the ultrasonic cleaner; one blade showed moderate to major change after only four cycles, the other showed slight change at that point and major change only after 32 cycles.

With stainless steel curets, ultrasonic cleanings or sterilization with autoclave or chemiclave can be used without visibly affecting the cutting edge. With carbon steel instruments, chemiclave is the least damaging sterilization method followed by anticorrosive treatment before autoclaving. Use of the autoclave without the anticorrosive pretreatment or use of an ultrasonic cleaner negatively affects the integrity of the surface and cutting edge of these instruments.