title: A laboratory study to determine the effects of universal and rotating ultrasonic inserts on wrist movement and scaling time efficiency of dental hygienists.
abstract: OBJECTIVE
  The purpose of this study was to determine if differences existed in range of wrist movements and scaling time efficiency of dental hygienists using a rotating ultrasonic insert when compared with a standard universal insert.
  
  
  METHODS
  A convenience sample of 32 consenting experienced dental hygienists who met inclusion criteria was invited to participate. Using a cross-over research design, the 32 participants were randomly assigned to one of the two subgroups. Subgroup A (n = 16) used the rotating universal ultrasonic insert on a typodont, rested for 15 min and the standard universal insert on a different typodont. Subgroup B (n = 16) used the standard universal ultrasonic insert on a typodont, rested for 15 min and the rotating universal ultrasonic insert on a different typodont. Each participant used the rotating and standard universal ultrasonic scaling inserts to remove 2 cm3 artificial calculus from two different typodonts for up to 15 min per insert. Scaling time efficiency was determined using a Modified Volpe-Manhold Calculus Index, measuring the amount of artificial calculus remaining after ultrasonic scaling. While scaling, each participant wore the WristSensor goniometry gloves, which determined changes in wrist movements (flexion and extension and ulnar and radial deviations), measured as a deviation from the neutral position.
  
  
  RESULTS
  A paired t-test (P = 0.05) using 30 subjects with useable data, revealed no statistically significant differences between the two different inserts in terms of wrist movements and scaling time efficiency. A multivariate analysis of variance revealed no statistically significant differences in the percentage of time dental hygienists were in high, medium or low-risk posture categories while using the rotating ultrasonic insert compared with the standard universal insert. Based on the results of this laboratory study, dental hygienists using a rotating ultrasonic insert appear to experience no ergonomic advantage in terms of wrist postures or timesavings over a standard insert.
authors.affiliation: Gene W. Hirschfeld School of Dental Hygiene, Old Dominion University, Norfolk, VA 23529-0499, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Hawn
authors.forename: S L
authors.initials: SL
authors.lastname: Tolle
authors.forename: M
authors.initials: M
authors.lastname: Darby
authors.forename: M
authors.initials: M
authors.lastname: Walker
mesh_terms: D018592:Cross-Over Studies; D012090:Cumulative Trauma Disorders / Q000517:prevention & control; D003728:Dental Calculus / Q000145:classification / Q000628:therapy; D003756:Dental Hygienists; D012534:Dental Scaling / Q000295:instrumentation / Q000379:methods*; D004526:Efficiency / Q000502:physiology*; D004867:Equipment Design; D006804:Ergonomics; D006801:Humans; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D017748:Time Management; D014464:Ultrasonic Therapy / Q000295:instrumentation*; D014954:Wrist Injuries / Q000517:prevention & control; D014955:Wrist Joint / Q000502:physiology*