Study of bone drilling dental tools wear: Measure and relation with cutting forces

Tool wear is a fundamental phenomenon that must be characterized to optimally plan machining operations. While wear is a well-known phenomenon for macrotools, with well-established wear parameters, the literature is less comprehensive in the field of microtools. The forms of microtool wear differ in general from macrotools. However, wear of microtools must be controlled. For example, referring to microtools used to drill the bone for dental implants, the control of tool and bone temperature is relevant, as the exposition of the bone to a high temperature can cause osteonecrosis. An uncontrolled tool wear can generate a local increase of temperature. The proposed contribution aims at showing our results on the three-dimensional geometric characterization of bone drilling dental tools wear and its relationship with cutting forces, considered as an indicator of the tool condition. An experimental campaign has been run, including 3D scans of the new tools and after the use. The comparison between scans allows a preliminary identification of the wear mechanisms. From these results, it will be possible to propose wear parameters for dental tools, which are expected to be reliable for microtools in general. Then the wear parameters will be associated to the cutting forces, and particularly the cutting torque, so that it is possible to decide whether a tool can still be used or has reached its end-of-service. The final aim is the definition of guidelines for the surgeon stating the correct use of bone drilling dental tools.