Abstract
Objective: The purpose of this study was to evaluate and compare the rate of bacterial contamination of reused and new unused burs after different sterilization sessions. Materials and Methods: The test group consisted of 40 used fissure burs, and the control group of 40 unused new fissure burs (total n = 80). The burs from both groups were precleaned according to standard protocols and then subjected to two sterilization sessions (high-and low-steam pressure autoclaving). After each sterilization session, the burs were transferred into incubation tubes which contained thioglycollate culture medium and were monitored daily for a period of 48 h to detect any bacterial growth. Data were collected and statistical analysis was done using Fisher's exact test. Results: Of the 40 burs of the test group, 2 burs (5%) showed positive bacterial growth, whereas no bur from the control group showed any sign of bacterial growth after high-pressure autoclaving. The colony structure and Gram staining were compatible with the growth of Staphylococcus epidermis. After a second sterilization session at low-pressure steam autoclaving, no bacterial growth was observed for the test group, but 1 bur (2.5%) from the control group showed bacterial growth and Gram-positive staining matched well with the growth of Brevibacterium species. Conclusions: The new and unused burs were 100% sterile after high-pressure steam autoclaving, whereas 5% of the reused burs appeared positive with bacterial contamination. After low-pressure steam autoclaving, reused burs were 100% sterile, but 1 new bur demonstrated bacterial contamination. (C) 2015 S. Karger AG, Basel