Summary The risk of infections in dental practices has been attracting for decades the interest of researchers from all over the world. A serious problem related to the transmission of blood-borne viruses is the thorough removal of organic matter, and mainly blood, from dental instruments when performing manual pre-sterilization decontamination. Application of benzidine test to prove the presence of blood traces on large and small dental instruments prepared for sterilization for the purpose of assessing the quality of the manual pre-sterilization decontamination. A total of 485 benzidine tests had been performed on selected 205 large and 280 small dental instruments visibly contaminated with blood. Of the total of 485 tested samples, blood traces were found in 63 (12.99 ± 1.53%). In the group of large instruments, positive benzidine test was obtained in 7.80% compared to 16.78% in the small instruments with the difference being statistically significant (p = 0.003). All 63 positive samples were additionally processed using ultrasound. Blood traces were found in 8 instruments with all of the positive samples being obtained from the barbed broaches. The manual cleaning does not guarantee decontamination of the dental instruments unlike the ultrasonic cleaning where any blood traces are being completely removed from the large instruments. In terms of the small instruments, there are still blood traces present after the ultrasonic cleaning which requires for it to be combined with a suitable enzyme cleaner, and the barbed broaches, as a requirement, should be used on a disposable basis.
