title: A comparative in vitro study of a magnetostrictive and a piezoelectric ultrasonic scaling instrument.
abstract: BACKGROUND
  The effects of magnetostrictive ultrasonic instruments and piezoelectric ultrasonic instruments on tooth surfaces seem to differ with regards to root debridement.
  
  
  OBJECTIVE
  The purpose of this study was to compare a magnetostrictive ultrasonic scaling instrument with a piezoelectric ultrasonic scaling instrument and a hand curette regarding time taken, calculus removal, tooth surface roughness (Ra), and SEM examination before and after instrumentation.
  
  
  METHODS
  30 extracted human teeth with subgingival calculus were assigned to one of three treatment groups (n=10). The working force was standardised for both ultrasonic instruments at 200 g and for the curette at 500 g.
  
  
  RESULTS
  The results revealed that the time needed for instrumentation was 126.1+/-38.2 s for the curette, significantly more than for the piezoelectric ultrasonic instrument (74.1+/-27.6 s; p<0.05) and 104.9+/-25.4 s for the magnetostrictive ultrasonic instrument. Remaining calculus was similar for all three groups. The end Ra values were significantly worse for the piezoelectric instrument (2.02+/-0.41; p<0.05) compared to 1.42+/-0.48 for the curette and 1.36+/-0.41 for the magnetostrictive instrument. The SEM examination revealed the smoothest surfaces but, subjectively, the most tooth substance loss after the curette, followed by the magnetostrictive instrument, with the least substance loss, and then the piezoelectric instrument, with medium substance loss.
  
  
  CONCLUSIONS
  The piezoelectric ultrasonic scaler was more efficient than the magnetostrictive ultrasonic scaler in removing calculus but left the instrumented tooth surface rougher.
authors: Clinic for Preventive Dentistry, Periodontology and Cariology, Centre for Dental Medicine, University of Zürich, Zürich, Switzerland.
authors: A
authors: A
authors: Busslinger
authors: K
authors: K
authors: Lampe
authors: M
authors: M
authors: Beuchat
authors: B
authors: B
authors: Lehmann
mesh_terms: D000704:Analysis of Variance; D003728:Dental Calculus / Q000473:pathology / Q000628:therapy; D012534:Dental Scaling / Q000295:instrumentation*; D004560:Electricity; D004867:Equipment Design; D006801:Humans; D008280:Magnetics / Q000295:instrumentation; D008855:Microscopy, Electron, Scanning; D011312:Pressure; D013223:Statistics as Topic; D013357:Subgingival Curettage / Q000295:instrumentation; D013997:Time Factors; D014070:Tooth / Q000648:ultrastructure; D014464:Ultrasonic Therapy / Q000295:instrumentation*