Biofilm on and structural damage of rotary cutting instruments after 5 cycles of clinical use and processing

Abstract

Background: Rotary cutting instruments (RCIs) are sterilized routinely. The authors aimed to analyze the structural integrity, presence of dirt, and microbial contamination of RCIs used in clinical practice after processing.

Methods: Eighty-four RCIs (42 carbide burs, 42 diamond burs) were divided into baseline, control, and test groups. The RCIs were evaluated by means of scanning electron microscopy and microbiological analysis. Evaluation criteria included presence of structural damage, dirt, biofilm, and isolated cells and their phenotypic profile.

Results: The carbide burs from all groups and diamond burs from the test groups had structural damage. Dirt was observed in the baseline and test groups. Three bacterial species were isolated from 4 RCIs (9.52%). An isolated cell was observed from 1 carbide bur. Biofilm was observed on 3 RCIs (7.14%).

Conclusions: RCIs should not be subjected to multiple uses; after the first clinical use they accumulate structural damage and dirt that hampers the cleaning step, causing failure in the sterilization process.

Practical implications: The presence of microorganisms and structural damage on the RCIs confirmed that they are not amenable to processing, a fact that characterizes them as a single-use health care product.

Keywords: Dental instruments; biofilm; microbiological analysis; scanning electron microscopy; sterilization.