Comparison of Pre-Cleaning Methods on the Sterilization and Microstructure of Dental Diamond Burs

Nova Southeastern University, Davie, Florida, USA

Objective. This study compared bacterial growth after autoclaving contaminated diamond burs pre-cleaned by four different methods. Background. Studies show autoclaving to be the most effective method to sterilize dental instruments including burs. It has been reported that autoclaving of diamond burs is not 100% effective. National guidelines require pre-cleaning prior to autoclaving but no studies compare pre-cleaning methods on sterilizing diamond burs. Methods. IRB approval was granted(2017-299). Twelve medium grit multiple-use diamond burs were used for testing of four pre-cleaning groups and 3 control groups for a total of 96 burs. These groups included positive controls, negative controls, single-use diamond controls and the four research groups. Each bur was contaminated by preparing one tooth per patient. In groups of 12, the burs were pre-cleaned by either manual scrubbing, ultrasonic, diamond cleaning stone, or steam cleaning. The pre-cleaned burs were autoclaved at 270° F for 35 minutes. They were placed in sterile tubes filled with Brain Heart Infusion broth under aseptic technique at 37° C for 72 hours. The presence of bacterial growth was assessed by measuring the absorbance values. Microstructure analysis was performed using Scanning Electron Microscopy (SEM). Results. After autoclaving, no bacterial growth was observed in any group. SEM studies demonstrated thatdiamond burs pre-cleaned by manual scrubbing removed the diamond chips. Conclusions. All pre-cleaning methods were equally effective in showing complete sterilization of diamond burs. Manual scrubbing of diamond burs is not recommended since it results in a compromised instrument. Grant. Funded by the HPD Research Grant (035067).