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

用改良的兔耳室(REC)研究了氢氧化钙作用于结缔组织后的营养不良钙化情况。将含生理盐水的Ca(OH)2注入REC，在活体显微镜下观察微循环随时间的变化。用药几分钟后，靠近氢氧化钙的微血管开始消失。3h后，在活体组织与液化区交界处可见大量沉淀物。他们在规模和数量上都变得很大，直到48小时才像一家银行一样合并。扫描电子显微镜和能谱分析表明，这些沉淀物中含有Ca、P、S和镁，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和力高达14周。骨库的组织面呈板状，从组织液中吸收钙和磷。银行似乎为裸露的牙髓组织提供了绷带，以便开始沉积修复性牙本质。Ca(OH)_2药理作用的特点可能是产生一种中和的沉淀物，导致营养不良的钙化，因此，高碱化性和坏死性组织产生作用是不可避免的，而这些性质被认为是负面的。含Ca(OH)_2的根管封闭剂“Sealtex”和“Caltal”以及盖髓剂“Dycal”产生了相同的沉淀物。这些药都有很高的碱度。然而，新研制的根管封闭剂的成分为Ca(OH)2和脂肪酸，其pH为中性，不产生此类沉淀物。但我们发现，含有氢氧化钙的根管封闭剂中存在两种不同类型的封闭剂。

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.