Akesson I, Hansson G A, Balogh I, Moritz U, Skerfving S
Department of Occupational and Environmental Medicine, University Hospital, Lund, Sweden.
Int Arch Occup Environ Health. 1997;69(6):461-74. doi: 10.1007/s004200050175.
To assess the work load in neck and upper limbs of dentists.
Twelve right-handed female dentists (six with and six without a history of definite neck/shoulder disorders, pair-wise matched for age) were studied when performing authentic dental work. Electromyography (EMG) was used to quantify the muscular load of the shoulders bilaterally and of the right forearm. Positions and movements of the head and wrists were measured, using inclinometers and electrogoniometers.
During work, the median load for the right upper trapezium muscle was 8.4% of the maximal voluntary EMG activity (MVE); during 90% of the time the load was > or = 3.3% MVE ("static" load). The figures were somewhat lower on the left side (7.0% and 2.5% MVE, respectively). Subjects with disorders had over all lower load levels for the trapezius muscles, although not statistically significant at < 0.05, than those without disorders. During a standardized reference contraction for the trapezius, the load was 17% MVE, and the quotient between MVE and torque [normalized to maximal voluntary torque (MVC)] was 0.5. These figures may be used for transformations. The muscular load on the right forearm was similar to the loads on the trapezius. The head was, on average, forward tilted > or = to 39 degrees, and during 10% of the time > or = 49 degrees. The left hand was held in more static positions, with palmar flexion and ulnar deviation, also reflected by lower angular velocities and repetitiveness, as compared with the right one, which was dorsiflexed.
Dentists are exposed to high load on the trapezius muscles bilaterally, and steep, prolonged forward bending of the head. Further, for the wrists the postures were constrained, but the dynamic demands were low.
评估牙医颈部和上肢的工作量。
对12名右利手女性牙医（6名有明确颈部/肩部疾病史，6名无，年龄配对）在进行实际牙科工作时进行研究。采用肌电图（EMG）双侧量化肩部和右前臂的肌肉负荷。使用倾角仪和电子测角仪测量头部和手腕的位置及运动。
工作期间，右上斜方肌的中位负荷为最大自主肌电图活动（MVE）的8.4%；90%的时间负荷≥3.3%MVE（“静态”负荷）。左侧的相应数值略低（分别为7.0%和2.5%MVE）。有疾病的受试者斜方肌的总体负荷水平低于无疾病者，尽管在<0.05时无统计学意义。在斜方肌的标准化参考收缩过程中，负荷为17%MVE，MVE与扭矩[归一化为最大自主扭矩（MVC）]的商为0.5。这些数值可用于换算。右前臂的肌肉负荷与斜方肌的负荷相似。头部平均向前倾斜≥39度，10%的时间≥49度。与背屈的右手相比，左手保持在更静态的位置，伴有掌屈和尺侧偏斜，这也表现为较低的角速度和重复性。
牙医双侧斜方肌承受高负荷，头部有急剧、长时间的向前弯曲。此外，手腕姿势受限，但动态需求较低。
