Wintergerst Ana M, Throckmorton Gaylord S, Buschang Peter H
National University of Mexico (UNAM), Graduate School of Dentistry, Mexico City, Mexico.
Arch Oral Biol. 2008 Apr;53(4):369-75. doi: 10.1016/j.archoralbio.2007.10.012. Epub 2008 Feb 21.
This study analysed how bolus hardness and size affect within-subject variability of chewing cycle kinematics. Two independent prospective studies were performed; both tracked chin movements using an optoelectronic recording system. Computer programs identified each subject's ten most representative cycles, and multilevel modelling procedures were used to estimate variances. One study evaluated 38 subjects who chewed 1, 2, 4 or 8 g of gum presented in random order. The second study evaluated 26 subjects who chewed approximately 2.5 g of harder (670 g) or softer (440 g) gum, also presented in random order. In terms of bolus size, the 2g and 1g boluses produced the least and greatest relative within-subject variability, respectively; the largest differences were found for cycle duration and excursions. Within-subject variability when chewing the harder gum was consistently greater than when chewing the softer gum, except for lateral movement towards the balancing side. Because bolus hardness and bolus size influence within-subject variability differently, they must be taken into consideration when designing experiments to study masticatory kinematics. We conclude that a 2g bolus of soft gum should be used in studies of chewing cycle kinematics in order to reduce within-subject variability and increase statistical power.
本研究分析了团块硬度和大小如何影响咀嚼周期运动学的个体内变异性。进行了两项独立的前瞻性研究；两者均使用光电记录系统追踪下巴运动。计算机程序识别出每个受试者最具代表性的十个周期，并使用多水平建模程序来估计方差。一项研究评估了38名受试者，他们以随机顺序咀嚼1克、2克、4克或8克口香糖。第二项研究评估了26名受试者，他们以随机顺序咀嚼约2.5克较硬（670克）或较软（440克）的口香糖。就团块大小而言，2克和1克团块分别产生了最小和最大的个体内相对变异性；在周期持续时间和偏移方面发现了最大差异。除了向平衡侧的侧向运动外，咀嚼较硬口香糖时的个体内变异性始终大于咀嚼较软口香糖时的个体内变异性。由于团块硬度和团块大小对个体内变异性的影响不同，因此在设计研究咀嚼运动学的实验时必须予以考虑。我们得出结论，在咀嚼周期运动学研究中应使用2克软口香糖团块，以减少个体内变异性并提高统计效力。
