| Dentists and dental hygienists are at a high risk for developing work-related musculoskeletal disorders (MSDs), including carpal tunnel syndrome (CTS). An important risk factor in dental practice is forceful pinching, which occurs most frequently during dental scaling. Ergonomically designed dental instruments may help reduce the prevalence of MSDs among dental practitioners. In these studies, dentists and dental hygienists performed a simulated dental scaling task using custom-designed periodontal instruments with different handle diameters, weights and shapes. The activity of four forearm muscles was recorded with electromyography, while thumb pinch force was measured with pressure sensors. Results showed that handle designs of periodontal instruments could affect hand muscle load and pinch force by up to 30% during a simulated periodontal scaling task. The instrument with a large diameter (10mm), a light weight (15g), and a slightly tapered shape required the least amount of muscle load and pinch force to use.;In addition to periodontal instrument handle design, the effects of hand stabilization on pinch force and hand muscle load during dental scaling were examined. Three different finger-rest positions were compared during a simulated scaling task. Using two finger rests to stabilize the hand was associated with reduced thumb pinch force and muscle activity, as compared to not using any finger rests.;In the final study the pinch force and forces at the instrument tip were measured while dental providers (6 dentists and 6 dental students) performed scaling on real patients. The mean peak pinch force (30.1+/-6.9 N) was a force level associated with an increased risk for the development of CTS and other upper-extremity MSDs. Dental students applied greater pinch force than experienced dentists, and the dentists were more efficient in the transfer of pinch force into useful forces at the instrument tip for scaling. Training in biomechanical principles during an early stage of a dental or dental hygiene career may help students establish good work habits in dental scaling and reduce the risk for developing musculoskeletal disorders. |
