Chapter 29 Ultrasonic Instrumentation Flashcards
Applies to sound (acoustic) energy, having a frequency above the highest that is audible to the human ear (20 kHz)
Ultrasonic
Foward and backward movement
Oscillation
Irrigant creating a continuous flow, demonstrating removing loosely attached biofilm and endotoxin from the root surface, in addition to flushing debris from the treatment site.
Lavage
Characterized by formation and explosive collapse of microscopic bubbles in a flowing liquid resulting from forces acting on the liquid. The violent collapse of the microbubbles forms high-velocity liquid jets that aid in debriding oral biofilm from the tooth surface.
Cavitation
Occurs near any object in oscillating motion in liquid, including ultrasonic scaler tips and cavitation bubbles, and is characterized by vigorous swirling motion of the fluid.
Acoustic microstreaming
The conversion of electrical current into high-frequency mechanical vibrations is attained by a transducer that is either what?
magnetostrictive/piezoelectric
The insert of the magnetoristrictive ultrasonic scaler is composed of?
A stack of thin nickel strips soldered together at the ends and attached by a connecting body to a tip
How is a piezoelectric ultrasonic scaler differentiated from a magnetoristrictive scaler?
The tip which screws onto the handpiece using a torque wrench, the handpiece contains a crystalline/quartz disc which contracts in response to alternating application of current
Ultrasonic debridement mechanisms of action
Mechanical, irrigation, cavitation, acoustic microstreaming
Vibratory action of the oscillating blunt tip against the deposit disrupts or ablates the deposit from the tooth’s surface
Mechanical
Lavage action of water flowing over tip flushes biofilm from the tooth’s surface and debris from the treatment site
Irrigation
Removal/disruption of biofilm by turbulent currents of water surrounding the tip
Acoustic microstreaming
Holds the insert to surround the nickel stack in a spiral of copper wire which generates a magnetic field upon application of electrical current, resulting in magnetostriction of the stack
Magnetorestrictive Handpiece
Houses control that regulates power level and water flow; provides connection between foot switch and handpiece
Magnetorestrictive Base unit
When engaged, sends electrical current through the base unit to the handpiece, activating movement of the tip
Magnetorestrictive Foot switch
The number of complete back-and-forth cycles (stroke) the oscillating tip completes per second, measured in kilohertz
Operating frequency
Screws onto handpiece by a torque-controlled wrench
Piezoelectric tip
Embeds ceramic or crystal discs that encircle a metal bar. The terminal end of the bar is threaded to allow attachment of the tip
Piezoelectric handpiece
Houses controls that regulate power level and water flow, provides connection between foot switch and handpiece
Piezoelectric base unit
When engaged, sends electrical current through base unit to the handpiece, activating movement of the tip
Piezoelectric foot switch
Stroke length is measured by?
displacement amplitude
How far the tip is displaced from a position of zero movement, represents half the peak to peak displacement of the tip and is measured in microns
displacement amplitude
A flow rate of what provides a sufficient flow of water for cooling and occurrence of microstreaming and cavitation?
20-30mL/min
Diameter refers to the width or thickness at the active area. True or false?
True
