title: An in vitro investigation into the cutting action of ultrasonic radicular access preparation instruments.
abstract: The aim of this study was to investigate the dentine cutting action of a CT4 and SJ4 radicular preparation inserts (Excellence in Endodontics/Analytic Technology, Orange, CA, USA) used in a Piezon Master 400 ultrasonic handpiece (Electro Medical Systems SA, Nyon, Switzerland). Calibration of the ultrasonic inserts was carried out at minimum, medium and maximum power settings using light microscopic measurement of the tip displacement amplitudes (x120 mag). Polished dentine samples were instrumented, at monitored loads, at the three chosen power settings, to produce uniform dentine cuts. The resultant dentine debris was collected for SEM analysis, and comparison with that produced by rotary instruments. The depth of dentine cut was measured at x30 magnification. Fracture of the SJ4 insert was noted at medium power setting. Results revealed a significant increase in both displacement amplitude and depth of dentine cut with power setting (ANOVA P < 0.001). Dentine chip size increased with power, and differed in structure and appearance from those produced by rotary instruments. In conclusion, ultrasonic cutting is influenced significantly by power setting, and dentine chip formation is fundamentally different to rotary instrumentation.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Birmingham, Birmingham, UK.
authors.forename: M
authors.initials: M
authors.lastname: Waplington
authors.forename: P J
authors.initials: PJ
authors.lastname: Lumley
authors.forename: L
authors.initials: L
authors.lastname: Blunt
mesh_terms: D000704:Analysis of Variance; D002138:Calibration; D003804:Dentin / Q000601:surgery* / Q000648:ultrastructure; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008855:Microscopy, Electron, Scanning; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D014092:Tooth Root / Q000601:surgery* / Q000648:ultrastructure; D014464:Ultrasonic Therapy / Q000295:instrumentation*