Abstract
Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment. Expansion screw($Hyrax^{\circledR}$, Dentarum Inc.) was delevered to the palate and fumed 180 degrees every morning and evening for 8 days, giving a total expansion of 7.2mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Villanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattened-inactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased after 28-day retention.
급속정중구개확장 후 봉합부에서의 골조직 변화를 관찰하기 위해 유성견 4마리중 1마리는 대조군으로, 3마리는 실험군으로 사용하여 상악골에 급속정중이개장치를 장착한 후 매일 아침, 저녁으로 2회전($180^{\circ}$)씩 활성화시켜 8일간 정중이개를 시킨 직후, 보정 14일후, 보정 28일후에 각각 희생시켜 정중구개봉합부를 절취하여 각각 통법에 따라 H-E 염색, Villanueva 염색, 염기성 인산분해효소 염색, tartrate저항성 산성분해효소 염색을 시행하여 봉합부를 광학현미경으로 관찰하곤 다음과 같은 결과를 얻었다. 1. 정중구개봉합 확장 직후, 교원섬유 다발은 신장되었고 조골세포는 비활성화된 양상으로 소수 관찰되었으며 소수의 골양조직도 관찰되었다. 또한 수평절단 표본에서는 TRAP 염색에 양성반응을 보이는 세포가 소수 관찰되었으나 전두절단 표본에서는 구개골의 성장방향에 따라 비강에 인접한 부위에서 TRAP 염색에 양성반응을 보이는 파골세포들이 다수 관찰되었다. 2. 정중구개봉합 확장 14일후, 교원섬유다발은 신장되었고 ALP 염색에 양성반응을 보이는 조골세포가 소수 관찰되었으며, 수평절단 표본에서는 TRAP 염색에 양성반응을 보이는 세포가 거의 관찰되지 않았으나 전두절단 표본에서는 구개골의 성장방향에 따라 비강에 인접한 부위에서 TRAP 염색에 양성반응을 보이는 파골세포들이 다수 관찰되었다. 3. 정중구개봉합 확장 28일후, 교원섬유다발은 대조군과 유사한 양상으로 배열되었고 ALP 염색에 양성반응을 보이는 조골세포가 다수 관찰되었으며 많은 양의 미성숙골이 형성되었고, 수평절단 표본에서는 TRAP 염색에 양성반응을 보이는 세포가 거의 관찰되지 않았으나 전두절단 표본에서는 구개골의 성장방향에 따라 비강에 인접한 부위에서 TRAP 염색에 양성반응을 보이는 파골세포들이 다수 관찰되었다. 이상의 결과를 종합해볼 때, 정중구개봉합부를 급속확장시킨 후 신생골 형성은 보정 14일이 지난 후부터 관찰되기 시작하였으며, 보정 28일이 지난 후에는 신생골형성이 훨씬 왕성하게 진행되었음을 관찰할 수 있었다.
(Dept. of Dentistry, Graduate School of Chosun University)
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