Mandibular Movements in Hemi-mandibulectomy Patients during Injestion and Deglutition

在未进行手术重建的下颌切除术患者中，剩余的下颌节段不稳定且经常偏离。它在咀嚼和吞咽时的动作可重复性较低。本研究的目的是阐明在有和没有下颌骨连续性的下颌骨切除术患者中，每一种口腔功能的下颌运动的三维差异。选取无下颌连续性的4例（I组）和有下颌连续性的3例（II组）。他们的下颌运动记录使用下颌运动跟踪装置六自由度。在虚拟切牙点上对每次运动进行图形化评估，并分析下颌骨在额角、矢状面和水平面上的旋转角度。此外，在I组受试者中，在每次功能运动中应用4种通过改变咬合面宽度的钢板坡道进行分析。研究结果如下：组1中，虚拟切牙点的边界运动表现为不规则和不对称的包络，在额平面上偏离切除侧，而组2中表现为光滑和对称的包络。1组大鼠在边界运动、咀嚼时额平面旋转角度、吞咽时额平面和水平面旋转角度均显著大于2组。腭斜越宽，每次咀嚼动作在额平面上越平滑和宽，而在说话时下颌运动受到干扰的频率越高。下颌骨切除术患者的边界运动和所有功能运动的比较揭示了下颌骨在额平面旋转的特征运动。提示下颌骨旋转角度是评估下颌切除术患者下颌运动的一个有用参数。

In mandibulectomy patients who have not undergone surgical reconstruction, the remaining mandibular segment is unstable and often deviated. Its movements have low reproducibility during mastication and deglutition.The purpose of this study was to clarify three-dimensionally the differences in mandibular movements for each of these oral functions in mandibulectomy patients with and without mandibular continuity. Four mandibulectomy subjects (Group I) without mandibular continuity and three subjects (Group II) with mandibular continuity were selected. Their mandibular movements were recorded using a jaw movement tracking device with six degrees of freedom. Each movement was assessed graphically at the virtual incisor point and the rotational angle of the mandible in the frontal, sagittal and horizontal plane was analyzed. Furthermore, in Group I subjects, 4 types of the platal ramps by changing of the width of the occlusal sufaces were applied and analyzed during each functional movement.The findings were as follows ;1. In Group I, the border movements at the virtual incisor point exhibited an irregular and asymmetric envelope deviated to the resected side in the frontal plane, whereas Group II exhibited a smooth and symmetric envelope.2. In Group I, the rotational angle in the frontal plane during border movements, mastication and in the frontal and horizontal plane during deglutition were significantly larger than in Group II.3. The wider the palatal ramps were, the more smooth and wider each chewing stroke was in the frontal plane, whereas the more frequently the mandibular movement was interfered during speech.A comparison among border and all functional movements in mandibulectomy patients revealed characteristic movements in the rotation of the mandible in the frontal plane. It is suggested that the rotational angle of the mandible is a useful parameter for assessment of mandibular movements in mandibulectomy patients.