Healing pattern of the periodontium following luxation of rat molars : histologic & autoradiographic studies
치과 임상 전반에 걸쳐 문제가 되고 있는 치근 흡수에 관하여 많은 학자들이 그 치유양상에 관하여 보고하여 왔다. 그러나 치유과정에 있어서 어떤 경우에는 치아주위조직의 재조직화가 일어나 정상치유가 되고 어떤 경우에는 치근 흡수가 일어나는지에 관하여는 규명된 바 없다.
저자는 백서 하악 우측 제1대구치를 약 1mm정도 탈구시킴으로 치근막내에 초자질화 구역을 야기시킨 후 그곳에서 일어날 수 있는 치유과정을 1,3,7,10,14,21일의 간격으로 조직학적 및 H**3 -thymidine을 이용한 자가방사법적으로 관찰하여 다음과 같은 결과를 얻었다.
탈구 후 제1일부터 가압측(pressure side)에 일시적인 초자질화 구역이 나타났다.
표지된 세포는 치유과정중 제 7일 째 가장 많이 나타나고 제10일째 부터는 초자질화 구역이 소실되며 전 실험기간 중 가장 많은 신생 결합조직 세포의 출현이 있었다. 이때 표지된 세포가 치근막내에서 계속 나타나게 되면 치근 흡수의 현상이 나타났고 표지된 세포가 정상 표본에서와 같이 치조골과 백아질에 연한 신생 결합조직 세포에 더 나타나면 정상치유 과정을 밟았다. 이때는 골도세포와 백아모세포가 치조골과 백아질에 연하여 규칙적인 기능배열을 하였다.
이상의 결과로 골모세포와 백아모세포 및 치근막내 신생 결합조직 새포의 출현시기와 기능배열은 정상치유와 치근 흡수 현상에 중요한 영향을 미친다고 생각된다.
Periodontium have been of special interest for many authors to investigate the etiology and pathogenesis of root resorption which is one of the most important problem in modern clinical dentistry.
Root resorption has been demonstrated in accidentally traumatized teeth (Skitter 1960, Andreasen 1970, Birkedal-Hansen 1973) in human and experimentally it has been revealed in excessive orthodontic force (Reitan 1947, Reitan & Kvdm 1971), in
traumatic occlusion (Bhaskar & Orban 1955, Waerhaug & Hansen 1966) and in thermal irritation (Atrizadeh et al. 1971, Kvam 1972). Also it appears that external root resorption is an almost inevitable sequel to endodontically treated teeth (Erausquin & Devoto 1970) and to replanted and transplanted teeth (Natiella et al.1970).
Although the reasons for failure to reconstitute a normal periodontal ligament after injury and the subsequent development of root resorption are not known, several hypotheses have been proposed. Lee & Waerhaug(1961) suggested that the epithelial remits of Malassez may have the potential for inhibiting root
resorption. According to Johansen (1970) reattachment takes place in the "vascular zone" of the periodontal membrane without new formation of bone and cementum as a prerequisite. Hjorting-Hansen & Andereasen (1970) claimed that the direction of newly formed collagenous fibers have been shown to be important for the osseous healing. Erausquin & Devote (1970) and Melcher (1970) proposed that if, after the injury to a portion of the ligament, the connetive tissue cells which repopulate the wound are from the progency of the periodontal ligament cells, normal reconstitution ensued and if a portion of the wound is colonized from a source Outside the ligament, ankylosis may occur. Line (1974) reported that areas of the periodontal ligament which repopulated from the adjacent bone marrow ankylosed.
Generally hyalinized zones are usually present in the pressure side of the periodontal menbrane following injury. It has been shown that such tissue will diappear and the periodontium reorganized. Initially this reorganization is initiated essentially by cellular invasion and proliferation. However, in these healing procedures, normal healing may occur in some cases where periodontal reorganization is, or root resorption in other cases where it is not.
Albino rats of the Sprague-Dawley strain were used for this study. The mandibular right first molar of the rats were luxated about 1mm with the elevator. Each animal received intraperitoneally 1μCi/gram body weight of H**3-thymidine (Sp. Act. 6.7 Ci/mM) one hour prior to death. Specimens were available at 1,3,7,10,14 and 21 drys following luxation. The Jaws were dissected free, fixed with 10% formalin ana Bouin solution for 12hours, decalcified in 5% formic acid. The specimen embeded in
paraffin and sectioned at 5∼6μm. Step serial sections were coated with Kodak NTB-3 emulsion and exposed for 2 weeks before being developed. All slides were stained through the emulsion with hematoxylin and eosin and examined by light microscope.
Hyalinized zone of the periodontal ligament was always seen in pressure side of periodontium at 1 day after lunation. Labeled connective tissue cell of the periodontal ligament was markedly increased at 7 day after luxation and it was disappeared at 10 day and was repopulated by newly formed connective tissue cells
in peak at the same time. At 1 that time there was root resorption when labeled cello remain still in periodontal ligament and reorganization when labeled cells remain in the margin of alveolar hone and cementum with the aligned arrangement of osteoblast and cementoblast.
Consequently the functional arrangement and the period of proliferation of the osteoblast, cementoblast and fibroblast are important factors whether normal healing or root resorption will occur.