Assessment of local muscular load of dental practitioners

Hands and forearms are one of the most common localisations of musculoskeletal disorders (MSDs) among dental practitioners. The aim of this study was to objectively assess the local muscular load of hands and forearms of dental practitioners during various treatment procedures using the method of the integrated electromyography (iEMG). This method is used for health risk assessment and categorization of working operation within the official national methodology.

A total of 24 measurements were performed on 10 dental practitioners during 8 different dental treatments; mostly on those which are most frequent in clinical practice, i.e. endodontic treatment, tooth extraction, tooth restoration with filling and prosthetic treatment. The EMG Holter was used to detect the electromyographic potentials determining the local muscular load.

All the muscle groups of the forearm were relatively evenly loaded at work. During the dynamic work activity, the average time-weighted value of maximum voluntary contraction (%MVC) was in the range from 1 to 30 %MVC for all evaluated muscle groups. The mean average time-weighted value of %MVC did not exceed 6% (a critical limit of the mean average time-weighted value of %MVC) in any of the evaluated muscle groups. The results of the frequency analysis showed that large (55-70 %MVC) and rarely the limits exceeding values (above 70 %MVC) were observed for individual muscle groups. These forces are related to performing tasks at inaccessible locations associated with non-physiological working positions. The differences in the mean forearm muscle load between the upper limbs were statistically significant in total (p < 0.001), for flexors (p = 0.017) and for extensors (p = 0.006).

In view of the results of this study, the work of dentists can be ranked in category 2 in terms of the local muscle load factor according to the currently valid legislation in the Czech Republic.