Tetsuka Makoto, Saga Tsuyoshi, Nakamura Moriyoshi, Tabira Yoko, Kusukawa Jingo, Yamaki Koh-Ichi
Dental and Oral Medical Center, Kurume, Japan.
Kurume Med J. 2012;59(1-2):5-15. doi: 10.2739/kurumemedj.59.5.
To chew, it is necessary to maintain harmony between the masseter muscle and other organs. Various studies have been conducted on the masseter muscle, but none has examined the relationships among masseter muscle form, occlusal support of remaining teeth, and maxillofacial morphology. Thus, we conducted the present study using cadavers donated to anatomy practice. After the masseter muscle was extracted, its length, width, thickness, and volume were measured; histological observations were conducted; and the muscle fiber cross-sectional area and muscle density were calculated. In addition, denture use and non-use were examined. The results showed that when regional support loss occurs, muscle fiber thickness and density decrease. This in turn causes masseter muscle thickness and volume to decrease, resulting in muscle atrophy. Furthermore, excluding Eichner class A cases (all regions intact), the thickness of the masseter muscle is greatest when the premolar support region remains. The premolar support region was shown to have the most impact on masseter muscle morphology. These results suggest that atrophy of the masseter muscle can be arrested or improved with the use of dentures in the case of tooth loss.
要进行咀嚼，就必须维持咬肌与其他器官之间的协调。针对咬肌已开展了多项研究，但尚无研究探讨咬肌形态、余留牙的咬合支持以及颌面形态之间的关系。因此，我们利用捐赠给解剖实习的尸体进行了本研究。在提取咬肌后，测量其长度、宽度、厚度和体积；进行组织学观察；并计算肌纤维横截面积和肌肉密度。此外，还对是否使用义齿进行了检查。结果显示，当出现局部支持丧失时，肌纤维厚度和密度会降低。这进而导致咬肌厚度和体积减小，引发肌肉萎缩。此外，排除艾希纳A类病例（所有区域均完好）后，当磨牙前支持区域保留时，咬肌厚度最大。结果表明，磨牙前支持区域对咬肌形态的影响最大。这些结果提示，在牙齿缺失的情况下，使用义齿可阻止或改善咬肌萎缩。
