흰쥐의 치아 맹출과 치간 이개 과정에서 수종의 치주인대 단백질 발현의 변화에 관한 면역 조직화학적 연구

Abstract

치아의 맹출 과정과 치간이개로 유도된 치아 및 치조골의 흡수 과정에서 치주인대 세포와 치주인대 단백질의 기능을 알아보기 위하여, 발육 중인 흰쥐를 치근 형성 전, 치근 형성 시작과 치근 형성 및 맹출 시기로 구분하여 조직 표본을 제작하고, 또한 성 장 중인 흰쥐를 2주간 치간 이개시켜 조직표본을 제작하였다. 치주인대 섬유모세포에서 특이적으로 발현되며 치주인대의 분화와 성숙에 관여하는 PDLs22단백질과 치아와 치조골의 파괴와 흡수를 조절하는 것으로 알려진 RANKL과 OPG의 발현을 면역 조직화학적으로 연구하였다. PDLs22 단백질은 치근 형성이 시작되면서부터 치낭세포와 골모세포에서 발현되어, 치아가 맹출하는 과정에서도 그 발현이 계속 유지되었으나, 치간이개에 의하여 치주인대가 개조되는 부위에서는 발현이 감소하였다. RANKL은 치근형성 과정에서는 미약한 발현을 나타내었으나, 치아가 맹출하면서 발현이 증대되었으며, 치간이개에 의한 치근과 치조골 흡수과정에서는 치주인대세포, 골모세포, 치수세포 및 파치세포에서 발현이 증대되었다. OPG는 치근이 형성되는 시기에는 강한 발현을 보였으나, 치아가 맹출하면서 발현이 현저히 감소하였고, 치아와 치조골의 흡수가 진행됨에 따라서 발현이 다소 감소하였다. In this study, we attempt to investigate the mechanisms by which PDL cells regulate osteoclast formation and also tc know whether PDL retained their characteristic phenotype during tooth eruption and interdental separation. Rats were prepared at developmental days 21 (pre-root formation), 27(toot development), 34(advanced root formation/eruption) and at later times(adult rats). To induce severe resorption state of alveolar bone and tooth root, interdental separation with brass wire was performed between the lower first and second molars for 2 weeks in adult rats. Rat mandibles were demineralized and embedded in paraffin, and horizontal and frontal section were prepared for immuno-histochemical analysis using PDL-specific protein 22 (PDLs22), receptor activator of NFKB ligand (RANKL) and osteoprotegerin (OPG) antibodies. 1. Root formation and eruption stage of tooth development. 1) PDLs22 immunolocalization was observed in tooth follicle/PDL cells and osteoblasts throught out the root formation and eruption stages of tooth development. 2) RANKL expression became stronger at eruption stage than root formation stage of tooth development. 3) Strong expression of OPG was detected in follice/PDL cells of toot formation stage but it was decreased with tooth eruption. 2. Interdental separation between lower first and second molar 1) Comparared to normal animal, multinucleated osteoclasts and odontoclasts were markedly induced in the alveolar bone and tooth root with PDL remodeling in hematoxylin-eosin section. 2) PDLs22 expression was decreased with interdental separation. 3) RANKL expression was Increased with interdental separation in PDL fibroblasts, osteoblasts, odontoclasts and it lacunae, resorting dentin, cementum and bone matrix. 4) OPG expression was slightly decreased in the PDL cells adjacent to the alveolar bone and root surface with interdental separation. These results suggested that during tooth eruption and tooth movement, RANKL and OPG in the periodontal tissues are important determinants regulating balanced alveolar bone and tooth root resorption. And it is also suggested that PDL cells retained their characteristic phenotype during tooth eruption and interdental separation except for the short period of PDL remodeling.