This study investigates how dental chair design influences posture and ergonomic risk during clinical work. Dentists are particularly prone to musculoskeletal disorders (MSDs) due to prolonged static and awkward postures during treatment. Proper chair design is often assumed to help reduce such risks, but empirical data have been limited.
To address this, the researchers compared five different dental chair models with 22 right-handed dentists performing simulated treatment tasks on a phantom head. The participants’ full-body movements were captured using an inertial motion-tracking system, and ergonomic risk was continuously analyzed through the Rapid Upper Limb Assessment (RULA) method. Statistical analysis included the Friedman test with pairwise comparisons and Statistical Parametric Mapping (SPM) to detect differences across the motion data. Significance was set at p ≤ 0.05.
The results revealed no statistically significant difference in overall RULA scores between the chair models. All chairs produced RULA scores of 5 or higher, which correspond to an “uncomfortable and high-risk” ergonomic posture category. This indicates that, regardless of chair type, the participants remained exposed to a considerable risk of developing MSDs.
Some localized joint-angle differences appeared across certain chairs—for instance, differences between chairs 1 and 5 for the left shoulder, 2 and 4 for the right shoulder, and 1 and 3 for trunk and elbow positions. However, these variations were scattered and did not form a consistent or clinically relevant pattern.
In the discussion, the authors emphasize that chair design alone cannot significantly lower ergonomic risk in dentistry. Even with modern or ergonomically branded chairs, the working posture of dentists remains constrained by task demands, patient positioning, and visual access. Therefore, personal comfort and psychological preference should be prioritized when selecting chairs, rather than relying solely on presumed ergonomic superiority.
The authors recommend that future studies incorporate muscle-activity data (e.g., EMG recordings) and evaluate long-term fatigue and posture variability across a full workday to provide a more complete picture of ergonomic performance.
Ultimately, the study concludes that while dental chair design plays a supporting role, a comprehensive ergonomic strategy—including proper training, adjustable workspace design, frequent posture changes, and awareness of fatigue—is essential to effectively reduce MSD risk among dental professionals.
(Source: MDPI – Biomechanics, 2025, Vol. 12, Issue 4, Article 353)
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