title: Removal of simulated biofilm: a preclinical ergonomic comparison of instruments and operators.
abstract: BACKGROUND
  Periodontal scaling might cause musculoskeletal disorders, and scaling instruments might not only have different effectiveness and efficiency but also differ in their ergonomic properties. The present study assessed ergonomic working patterns of experienced (EO) and less experienced operators (LO) when using hand and powered devices for periodontal scaling and root planning.
  
  
  METHODS
  In an experimental study using periodontally affected manikins, sonic (AIR), ultrasonic (TIG) and hand instruments (GRA) were used by 11 operators (7 EO/4 LO) during simulated supportive periodontal therapy. Using an electronic motion monitoring system, we objectively assessed the working frequency and positioning of hand, neck and head. Operators' subjective evaluation of the instruments was recorded using a questionnaire.
  
  
  RESULTS
  Hand instruments were used with the lowest frequency (2.57 ± 1.08 s(-1)) but greatest wrist deviation (59.57 ± 53.94°). EO used instruments more specifically than LO, and generally worked more ergonomically, with less inclination of head and neck in both the frontal and sagittal planes, especially when using hand instruments. All groups found hand instruments more tiring and difficult to use than powered instruments.
  
  
  CONCLUSIONS
  Regardless of operators' experience, powered instruments were used more ergonomically and were subjectively preferred compared to hand instruments.
  
  
  CONCLUSIONS
  The use of hand instruments has potential ergonomic disadvantages. However, with increasing experience, operators are able to recognise and mitigate possible risks.
authors.affiliation: Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-University of Kiel, Kiel, Germany. graetz@konspar.uni-kiel.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Graetz
authors.affiliation: Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Plaumann
authors.affiliation: Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Rauschenbach
authors.affiliation: Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Jule
authors.initials: J
authors.lastname: Bielfeldt
authors.affiliation: Clinic for Conservative Dentistry and Periodontology, School of Dental Medicine, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Christof E
authors.initials: CE
authors.lastname: Dörfer
authors.affiliation: Department of Operative and Preventive Dentistry, Charité-University of Berlin, Berlin, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Schwendicke
mesh_terms: D018441:Biofilms; D003762:Dental Instruments; D012534:Dental Scaling / Q000295:instrumentation*; D004867:Equipment Design; D006804:Ergonomics; D006801:Humans; D008348:Manikins; D011187:Posture / Q000502:physiology*; D011795:Surveys and Questionnaires; D014464:Ultrasonic Therapy / Q000295:instrumentation*
keywords: Dental plaque; Dental scaling; Ergonomics; Musculoskeletal diseases; Self-assessment