All instruments laid out for the treatment of a patient - whether used or not - have to be regarded as "contaminated" by micro-organisms etc. They have to be routinely submerged into a disinfectant solution at the end of the treatment, even if a later sterilization is intended or planned.

It is important here to prepare or use a proper disinfectant solution by observing the correct concentration and usage time and especially a regular renewal of the disinfectant solution, whether contamination is visible or not.