Investigation of the Pharmacological Effect of Calcium Hydroxide with a Rabbit Ear Chamber Technique

采用改良兔耳室（REC）观察钙（OH）_2作用于结缔组织后的营养不良钙化现象。将Ca(OH)_2加入生理盐水中，在生命显微镜下观察REC内微循环随时间的变化。几分钟后，Ca(OH)_2附近的微血管开始消失。3小时后，在活体组织与液化区交界处，观察到许多沉淀。它们在规模和数量上都变得很大，像银行一样组合在一起，直到48小时。SEM和EDX分析表明，这些析出物含有Ca、P、S和Mg，它们是由Ca(OH)_2与组织液中和产生的。这些沉淀库与微循环的亲合力长达14周。细胞壁的组织侧呈板状，从组织液中吸收钙和磷。这似乎为暴露的牙髓组织提供了一个绷带，开始修复牙本质的沉积。Ca(OH)_2的药理作用的特点可能是使这种中和沉淀物引起营养不良的钙化。因此，Ca(OH)_2的高碱化性质和产生坏死性组织的作用是产生这些沉淀的必然因素，而这些性质被认为是负面的。含Ca(OH)_2的根管封闭剂“Sealapex”和“Calvital”与牙髓封盖剂“Dycal”产生相同的沉淀。这些药的碱度都很高。而新研制的根管封闭剂，其成分为Ca(OH)_2和脂肪酸，pH为中性，不会产生此类沉淀物。需要进一步的实验来确定哪一种作为根管材料的性能更好，但我们发现所谓的含Ca(OH)_2的根管密封剂有两种不同的类型。

An improved rabbit ear chamber (REC) was used to investigate the dystrophic calcification after Ca(OH)_2 application on connective tissues. Ca(OH)_2 with saline was inserted into the REC and the change in microcirculation inside was observed under the vital-microscope with passage of time. Several minutes after the application, microvessels within the close vicinity to Ca(OH)_2 began to disappear. After 3 hours, at the border between the living tissue and liquefacted area, many precipitates were observed. They became large in both size and number to combine like a bank until 48 hours. SEM and EDX investigation revealed that these precipitates contained Ca, P, S,and Mg and they were produced by neutralization of Ca(OH)_2 with the tissue fluid. These precipitate bank had a high affinity with the microcirculation as long as 14 weeks. The tissue-side of the bank became a plate-like form, absorbing Ca and P from the tissue fluid. It seems that the bank affords a bandage for the exposed pulp tissue to begin the deposition of reparative dentine. The characteristic leature of the pharmacological effect of Ca(OH)_2 may be to make such a neutralized precipitates that introduces dystrophic calcification.Therefore, the high alkalizing property and necrotized-tissue producing effect of Ca(OH)_2 were inevitable to make these precipitates, whereas these properties were thought to be negative. The Ca(OH)_2-containing root canal sealers, "Sealapex" and "Calvital", and the pulp capping agent "Dycal" produced the same precipitates. These medicine have all high alkalinity. However, the newly-developed root canal sealer, which constituents were Ca(OH)_2 and fatty acid, was neutral in pH and did not produce such precipitates. It need further experiments to determine which is a bette property as an endodontic materials, but we found out that there were two different types in so-called Ca(OH)_2-containing root canal sealers.