The Deterioration of the Surface of Dental Burs by Washing and Sterilization

Recently, the number of accidents, involving dental bur break has increased in our hospital. It has been thought that one of the causes of the accident might be the deterioration of dental burs by the repeated washing and sterilizing. Purpose : This study aims to clarify the cause of the deterioration of dental burs in the process of washing or sterilizing. Materials and methods : The burs examined were the Zekrya burs made of tungsten carbide. The burs were washed by ultrasonic cleaner or by washer-disinfector, or sterilized by autoclave or by the HPDS (Hydrogen peroxide/Plasma Discharging Sterilization at low temperature). After repeating the washing or sterilizing process 30 times, the surface of each bur was observed by the EPMA (Electron Probe Micro-Analyzer) by 7,000-time magnification. Results: 1. The EPMA analysis showed that the surfaces of the blade of the dental burs treated by the HPDS contained many cracks. 2. The surfaces of the blade of the dental burs that were treated by the autoclave showed a porous aspect. 3. Ultrasonic cleaner and washerdisinfector did not influence the surfaces of the blade of the dental burs. 4. At macroscopic level, the level of the surface deterioration may be distinguished by the darkening tendency of the bur's color.