Effect of Different Types of Stools on Working Posture, Discomfort and Productivity in Dentistry

Abstract

Objective: This study evaluated different stools on working posture, discomfort and productivity during cavity preparations. Methods: An experimental laboratory-based simulated study was performed. The response variables were the variation in bilateral muscle contraction of the abdominal, lumbar, and posterior thigh regions using surface thermography as proxy measure; the risk of developing musculoskeletal disorders in the upper limbs using the Rapid Upper Limb Assessment; adherence to ergonomic posture requirements through the modified Compliance Assessment Dental Ergonomic Posture; angular deviation from the neutral position of the neck and trunk; perception of discomfort in the abdominal, lower back, and thighs using the visual analogue scale; and productivity. Independent variables were the type of stool (conventional, saddle, or Seatball) and arch (upper or lower). A single operator performed class I tooth preparations on arch simulator plates during 90-minutes per period. For each experimental condition, 10 postural assessment periods were used (N=60 postures). Descriptive statistics were analyzed, and the assumptions of normality and homoscedasticity were verified. Two-way parametric and non-parametric ANOVA with Tukey’s post-hoc test were performed (α=0.05). Results: There was no significant interaction between stool and arch for any evaluated variable (p=0.449–0.915). There was higher muscle contraction during work with conventional stool for the lumbar region (p<0.001), better angular deviation from the neutral position of trunk (p<0.001) and better compliance with ergonomic posture requirements (p=0.004) when working on the lower arch. It was also observed an increased perception of discomfort in the thigh region with the saddle seat (p<0.001). Conclusion: The different types of stools influenced only muscle contraction and perceived discomfort. The conventional stool increased lumbar region muscle contraction, while the saddle seat produced greater discomfort in the thigh region. Procedures performed on the upper arch were associated with reduced compliance with ergonomic posture requirements and greater angular deviation of the trunk.