Comparative ergonomic evaluation of the hand-pieces of three instrument series for root planning

Introduction: Musculoskeletal disorders (MSD) are the most frequent cause of disability in the working population, exceeding accidental trauma in frequency. The risk of developing work-related upper limb disorders (WURLDs) is high among dental hygienists and the most frequently affected are elderly subjects and women. Since such disorders can have a negative effect on the working life and on the quality of life, it is of vital importance to put in place preventive measures. Aim: To make a comparative analysis of the hand-pieces of three different manual instruments used for root planning. Materials and Methods: To evaluate the physical characteristics (section, diameter, external surface, weight) of the hand-pieces of three series of instruments for root planning, twentynine dental hygienists students were videoed while working clinically. They were also interviewed using a specific questionnaire to determine subjective preferences in terms of perceived efficacy, safety, comfort and general acceptability of the hand-piece used. Results: Lightness, full-cylindrical section with larger- diameter ends, and coating with anti-slip silicone are the most appreciated characteristics of a handpiece. Conclusions: Ergonomic analyses of manual instruments are not frequent in the dental field, and the literature reports no guidelines to guide selection of the type of hand-piece of manual instruments. The data gathered may help manufacturers in designing new manual instruments, and guiding professionals in their selection.