Research for Clarifying Aetiologic Factors of Periodontal Disease -the Role of Neutrophil-

本研究旨在探讨中性粒细胞在牙周病发生发展中的作用。在动物实验中，采用组织学和组织计量学方法观察长期甲氨蝶呤诱导的中性粒细胞减少对牙周组织的影响，实验侧动物在左侧上颌第一、第二磨牙牙间隙内插入一根尼龙线，右侧动物作为对照侧，不做任何处理。然后将动物分为两组，一组注射1.0mg/kg的甲氨蝶呤（MTX），另一组不注射MTX。结果表明：M T X注射组白色细胞和中性粒细胞在3 ~ 9周明显减少;未注射MTX组在第7周和第9周表现为轻度牙龈炎和中度牙槽骨吸收。实验侧MT X注射组在第7周和第9周出现严重的牙槽骨吸收，两组间骨吸收差异有统计学意义。本研究结果表明，长期的M T X诱导的中性粒细胞减少症使中度牙周炎转变为重度牙周炎。从人类先天性中性粒细胞减少症的研究，也表明中性粒细胞在牙周病的发生发展中起着重要作用。

The purpose of the present study was to investigate the role of neutrophil on the development of periodontal disease. In animal study, the effect of a long-term methotrexate-induced neutropenia on the periodontal resion was histrogically and histometrically investigated.In the experimental side of the animals, a suturing nylon thread was inserted into the interdental space between the left maxillary 1 st and 2 nd molars.The right side of the animals of the same area was used as control side without doing any treatments. Then, the animals were divided equally into two groups.The animals in one group were injected with 1.0mg/kg of methotrexate (MTX), whereas in the another group with no injection of M T X. Results obtained were as follows.The numbers of white blood cell and neutrophil in the M T X injected group decreased remarkably from 3 to 9 weeks. The experimental side of non M T X injected group showed a slight gingival inflammation and moderate alveolar bone resorption at 7 and 9 weeks. In the experimental side of M T X- injected group, severe alveolar bone resorptions were found at 7 and 9 weeks.The difference of bone resorption between these two groups was statistically significant. The results of the present study indicated that long-term M T X induced neutropenia changed the moderate periodontitis into the severe one. From the study of congenital neutropenia in human beings, it was also suggested that neutrophil play a important role for developing of periodontal disease.