Failure analysis of eleven Gates Glidden drills that fractured intraorally during post space preparation. A retrieval analysis study
Abstract The purpose of this study was to determine the failure mechanism of clinically failed Gates Glidden (GG) drills. Eleven retrieved GG drills (sizes #1 to #3) which fractured during root canal preparation were collected and the fracture location was recorded based on macroscopic observation. All fracture surfaces were investigated by a SEM. Then the fractured parts were embedded in acrylic resin and after metallographic preparation, the microstructure and elemental composition was evaluated by SEM and EDS. The Vickers hardness (HV) of all specimens was also determined. Macroscopic examination and SEM analysis showed that the drills failed near the hand piece end by torsional fatigue with fatigue cracks initiating at several locations around the circumference and propagating toward the center. Final fracture followed by a tensile overloading at the central region of cross section. Microstructural analysis, hardness measurements and EDS show that the drills are made of a martensitic stainless steel like AISI 440C. Based on the findings of this study, clinicians should expect fatigue fracture of GG drills that have small size during root canal preparation. Selection of a more fatigue resistant stainless steel alloy and enhancing the instrument design might reduce the incidence of quasi-cleavage fracture on GG drills.
An accident with a Gates Glidden drill in endodontic practice.
An unusual accident in clinical endodontic practice is described. The Gates Glidden drill is currently being used for establishing straight-line access in endodontic practice (1). One potential hazard in using the Gates Glidden drill is that it can separate within the canal (2). This article reports an accident involving a Gates Glidden drill separating in the elbow of a dentist during endodontic practice and to discuss the safety of using a Gates Glidden drill.
The Effectiveness of Two Approaches to the Teaching of High School American History
The purpose of this study was to test the effectiveness of studies in depth utilizing selected materials which had been developed for teaching high school American history.