Cleaning Ability of Different Ultrasonic Cleaning Solutions

Objective: Ultrasonic cleaning has been shown to be a valid method of cleaning instruments prior to sterilization, but limited studies compare the effectiveness of different solutions. This study evaluated the cleaning efficacy of commercial ultrasonic cleaning solutions. Methods: Used were 18 ultrasonic cleaning agents (general purpose, enzymatic and germicidal, in liquid, powder, and tablets forms), a tap water control and one ultrasonic cleaning unit. Each cleaning run included 15 dental instruments with five (surgical scissors, dressing pliers, tissue forceps, cement spatulas, and mouth mirrors) soiled by immersion of their working ends in defibrinated sheep blood containing hydroxyapatite (0.05g/mL). Air-drying for 60 minutes followed. All solutions were fresh, made according to manufacturer recommendations and degassed. Instruments went into a basket and the unit operated for ten minutes. Baskets underwent immersion rinsing in three tap water baths. Saline-moistened sterile cotton tipped applicators went over the working ends. The applicator then went into 2.0mL of saline and vortexed for ten seconds. Measurement of blood was employed by clinical laboratory dipsticks (Hemostix®). Comparison of blue color development to standards determined relative numbers of red blood cells present. A t-test determined cleaning effectiveness between solutions. Results: Surgical scissors were the most difficult instrument to clean. One of the germicidal cleaning solutions produced the poorest cleaning (p<0.01). As expected, tap water was a poor cleaner, yet performed equal to three of the commercial products and better than one (p<0.01). In general, solution cleaning varied more by brand than by type. However, enzymatic powders did perform significantly better (p<0.01) than enzymatic tablets. Five cleaning solutions as a group performed better (p<0.01) than the others tested. Conclusion: Cleaning efficacy varied among instruments as well as the cleaning solutions. One powdered enzymatic cleaner was the most effective. Complete removal of blood was uncommon, especially when testing surgical scissors.