Development of a validated process for manual preparation of dental transmission instruments

The goal of the study was to develop a validated manual preparation process that conforms to the requirements of validation guidelines. Twelve dental transmission devices from various manufacturers (turbines, handpieces, and contra-angle handpieces) were artificially contaminated with bovine hemoglobin for the test. Ten microliters (corresponding to 800 μg) of bovine hemoglobin solution (concentration 80 mg/ml) was pipetted into the spray water and spray air channels. The manual preparation was conducted by blowing air through the spray channels of the transmission instruments through an attachment to a treatment unit (model 1060T, KaVo, Biberach, Germany) for 5 s. The spray channels were cleaned with WL-Clean (Alpro, Georgen, Germany) as directed by the manufacturer. The spray channels were disinfected with WL-Cid (Alpro) and the spray channels were blow-dried with WL-Dry (Alpro) at the end of the exposure time as directed by the manufacturer. To determine the protein content (protein residue analysis) in the channels of the transmission instruments, 2 ml of an alkaline SDS solution (1%; pH 11) was flushed through the channels. For the quantitative protein residue analysis, the Biuret method was used as described in DIN EN 15883-1:2006. After the application of this method, all results of the protein residue analysis were within the acceptance criteria of the validation guideline. The newly developed manual preparation process is therefore confirmed as suitable from a hygienic viewpoint for preparation of transmission instruments in the dental practice.