Development of force-endurance models for simulated scaling task

Force exertion is critical in grasping and holding activities at submaximal levels. Exertion misjudgments lead to musculoskeletal disorders (MSDs) impairing performance and productivity. Published literatures on grasping have addressed the force balance and endurance issues for non-prehensile movements of hand. However, little information is available on the force exerted in precision gripping employed in healthcare which is the main focus of this study. Lack of information on fatigue with precision gripping motivated this research to establish force-endurance relation for simulated dental task. A preliminary study was performed to establish the methodology. Results from the preliminary study provided directions to investigate the research question of how long can dental professional exert and hold using modified pencil-hold before fatiguing. This research question was addressed by developing a model between force exertions and time for a simulated dental task. Periodontal scaling was identified as the representative healthcare task to be simulated. Sixty participants (30 novices and 30 experts) participated in a simulated dental scaling task. Exertion level was varied at six levels (100–40% MVC). There were two hand conditions namely, gloved and bare handed. Endurance times were recorded as were the finger forces through “finger tactile pressure sensor”(TPS) system. Models for endurance times were developed and validated using the data. This research is first of its kind on precision grasps used in dentistry whose implications and recommendations have been discussed.Relevance to industryThere is a gap in estimating endurance times for precision gripping. This study provides fundamental information in estimating endurance time for modified pencil-holds commonly employed in periodontal tasks by dental hygienists. The findings of this study will be relevant to healthcare and other industries in providing fatigue allowances for a healthier society.

► Force exertion is critical in grasping and holding activities at submaximal levels.
► Information not available on the force exerted in precision gripping in healthcare.
► Endurance time was recorded in simulated dental task at different levels of exertion.
► Models for endurance times were developed and validated using the data.