Cleaning of dental handpieces and associated parameters: Internal and external cleaning, drying and rotation.

Purpose To evaluate the cleaning of dental handpieces and its associated parameters, internal, external cleaning and drying, and rotation, for two washer-disinfectors: Teon+ by W&H, and a dental rack for WD290 by Belimed. Methods An original method was developed with resin flags on dental burs to assess the inner rotation during the cleaning cycle. Concerning the cleaning and drying evaluation, three groups (9, 24 and 22 handpieces) were used in different conditions: soiled with Soil Test, soiled with heparinized blood, used in real conditions after a dental procedure, and clean (as control). Cycles were performed with the two washer-disinfectors, followed by a visual evaluation and a biuret reaction test. Results The method we developed was effective to assess the inner rotation of handpieces. The internal cleaning was successful for real conditions and control handpieces, but unsuccessful for all the artificially soiled handpieces except one. All the handpieces showed substantial humidity on their inner surfaces after cleaning. The internal cleaning of handpieces and its evaluation are both difficult to perform. A questioning about the relevance of some tests required in the ISO 15883 about handpieces requires further study. Cleaning devices and their parameters should be optimized to offer better cleaning skills, and testing-tools should be developed and validated to easily assess their performances. Clinical significance Easy-to-use testing tools should be developed and validated, and dental handpiece cleaning tests should be redefined to fit with the reality of practices. According to the actual performance of cleaning, and even though sterilization will largely contribute to the reduction of the infectious risk of internal handpiece structures, it is unclear whether cleaning procedures can ensure totally safe practices.