Objective:: Pathogenic microbes may be transmitted directly from the orthodontist to the patient or from the patient to the doctor, and indirectly from patient to patient. The latter may occur via contaminated instruments or surfaces, and is referred to as cross-contamination. The objective of this study was to evaluate the extent of bacterial contamination of orthodontic pliers and the efficacy of the disinfection techniques applied after clinical use. We also sought to examine under standardized conditions the virucidal, bactericidal and fungicidal effects of disinfection techniques used in practice. Materials and Methods:: The efficacy of various disinfection methods was determined after clinical use in-vivo on 10 test subjects and in-vitro with deliberate contamination. The following disinfection methods were tested: 1. Iso-Septol spray 2. Incidur® spray 3. Trough disinfection in combination with 5% Sekusept® Plus solution 4. Ultrasound bath in combination with 5% Sekusept® Plus solution 5. Thermal disinfection For in-vitro contamination we used the test organisms Staphylococcus aureus, Escherichia coli, Candida albicans, Coxsackie virus B4, HSV 1, and Adenovirus type 5. The tests were carried out six to eight times for each organism. The Weingart pliers and distalend cutters were tested. The criteria for effective disinfection were a reduction in infectiosity of five log steps (for bacteria and fungi) or four log steps (viruses). Statistical analysis was carried out using the Wilcoxon and Whitney U-test. Results:: The presence of contamination following clinical use was not adequately eliminated with all disinfection methods. The spray methods exhibited shortcomings in disinfection. For the type of contamination defined, trough disinfection with 5% Sekusept® Plus and the Incidur® and Iso-Septol spray disinfection methods provided insufficient disinfection. Conversely, the ultrasound bath with 5% Sekusept® Plus solution and steam disinfection met the criteria for effective disinfection for all microbes. No statistically significant difference was found between the oiled and unoiled states. In some cases, there were slightly higher rates of contamination with the Weingart pliers as with the distalend cutters. However, these were not statistically significant. Conclusions:: It should be possible to disinfect lipophilic viruses and the usual bacterial infections adequately with all methods, provided that the use of sprays and trough disinfection is preceded by cleaning with brush and water, followed by drying. With hydrophilic viruses, however, the spray and trough disinfection methods are limited in their efficacy and cannot be considered adequate. Exclusively chemical methods are therefore less effective than thermal or physical-chemical methods. Thermal disinfection and the ultrasound bath in combination with 5% Sekusept® Plus are clearly superior to spray disinfection and trough disinfection alone. The ultrasound bath and thermal disinfection can therefore be recommended for the disinfection of orthodontic pliers. We recommend that the pliers be cleaned beforehand due to their uneven surface
