Magnetostriction is defined as the changing of a material’s physical dimensions in response to changing its magnetization. The conversion is attained by either a magnetostrictive or piezoelectric transducer. Ultrasonic dental instruments convert electrical current into high-frequency (25–30 kHz) mechanical vibrations (Lea and Walmsley, 2009). ![]() Ultrasound is used in many different fields, typically to penetrate a medium and measure the reflection signature (e.g., sonography used in obstetrics) or to supply focused energy (e.g., ultrasonic cleaning of jewelry) ( Figure 3.1).įigure 3.1 Range of sound frequencies. The term ultrasonic applies to sound (or acoustic) energy having a frequency greater than 20 kHz, above the range audible to the human ear (Walmsley, 1989). Humans can hear sound at frequencies up to 20,000 Hz or 20 kHz. Sound is a form of energy produced by vibrations. (Walmsley et al., 1984 Khambay and Walmsley, 1999). ![]() Ultrasonic scaling instruments oscillate (move forward and backward) a typically blunt metal tip at a high-frequency producing mechanical vibratory, cavitational and acoustic microstreaming forces that remove/disrupt the deposits. Hand scaling instruments (sickles, curettes, files, hoes, and chisels) remove/disrupt the deposits by manually stroking a bladed cutting edge across the tooth surface to mechanically break the bond between the deposit and the tooth (Lea and Walmsley, 2009). Adjust the operational variables as necessary in order to operate the ultrasonic scaling unit at a level of acoustic power appropriate for the treatment objective.Īs presented in Chapter 1, the objective of periodontal debridement is to reduce periodontal pathogens and promote periodontal health by disrupting and removing deposits, ranging from biofilm to calculus, without over-instrumentation of the root surface.Explain the relationship of key operational variables to the acoustic power produced by the ultrasonic scaling unit.Define the mechanisms of action by which ultrasonic instruments remove deposits from the tooth surface.Differentiate between magnetostrictive and piezoelectric ultrasonic transduction.On completion of this chapter, the student will be able to:
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