矯正的歯の圧下移動に伴うヒト歯髄内血管運動神経の変化に関する病理組織学的ならびに免疫組織化学的研究

The dental pulp is unusual in being ensheathed by hard tissue and therefore the access of blood vessels and nerves is possible only through the tooth's apical foramen. The vitality of the pulp and its blood supply are closely related each other and the function of the vascular system profoundly affects the function of the pulp in physiological and pathological states. It is well-known that the vasomotor nerves regulate the blood flow, blood pressure and vascular permeability. The purpose of this study was to elucidate the relationship between changes of blood flow and vasomotor nerve during intrusive tooth movement in human dental pulp immunohistochemically and ultrastructurally. One hundred and forty human pulp tissues were obtained from premolars extracted for orthodontic reasons, aging from 12 to 27 years old. Two different orthodontic forces of 50g and 150 g were applied to each premolar in the intrusive direction using closed coil spring made of Ni-Ti. The premolars were extracted 1,14 and 28 days after tooth movement. Each extracted tooth was longitudinally divided into two pieces immediately after extraction and immersed in fixative to preserve the pulpal tissue, Deparaffinized sections at 5 μm thickness were stained immunohistochemically with antisera for S-100 protein and neuron specific enolase (NSE). The sections were lightly counterstained with 1% methyl green. Ultrathin sections were stained with uranyl acetate and lead citrate, and examined in a JEM 1200 EX electron microscope. The results were as follows : 1. At one to 14 days after tooth movement, hyperemia and enlargement of blood vessels were found in the 150 g group as compared with the 50 g group. In quantitative evaluation of nerve fibers by CAS-2OO, the both experimental groups showed the similar findings to the control group. But in the 150 g groups, the nerve terminals around the hyperemia and enlargement of some blood vessels also decreased in several places. The number of synaptic vesicles in the terminal axon decreased with the decreasing size of the terminal axons in the 150 g groups. 2. At 14 days after tooth movement, those findings gradually improved but healing processes were delayed in the 150 g group. In quantitative evaluation of nerve fibers by CAS-2OO, the nerve terminals around the blood vessels remarkablely increased in both experimental groups and the terminal axons rich with synaptic vesicles were observed around the arterioles. 3. At 28 days after tooth movement, these findings were especially improved in the 50 g group. In quantitative evaluation of nerve fibers by CAS-200,both experimental groups showed the similar findings to the control group and the ultrastructural observation of the terminal axons These findings suggest that the changes of the distribution and shape of pulpal nerve fibers and vasomotor nerves more relate to the intrusive force in apical area and those changes are improved gradually after loading.