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

本文用改良兔耳室（REC）观察Ca（OH）_2作用于结缔组织后的营养不良性钙化。将Ca（OH）_2与生理盐水混合液注入REC内，在活体显微镜下观察REC内微循环随时间的变化。应用后数分钟，Ca（OH）_2附近的微血管开始消失。3小时后，在活组织和坏死区域之间的边界处，观察到许多沉淀物。他们在规模和数量上都变得很大，像银行一样联合收割机，直到48小时。扫描电镜和能谱分析表明，这些沉淀物中含有Ca、P、S和Mg，是Ca（OH）_2与组织液中和的产物。这些沉淀物库与微循环有很高的亲和性，长达14周。组织侧的银行成为一个板状的形式，从组织液中吸收钙和磷。看来，银行提供了一个绷带，为暴露的牙髓组织开始沉积修复牙本质。Ca（OH）_2药理作用的特征可能是产生一种中和沉淀，引起营养不良性钙化，因此Ca（OH）_2的强碱化性和坏死组织生成作用是产生这些沉淀的必然，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与盖髓剂Dycal产生相同的沉淀。这些药都是高碱性的。而新研制的根管充填剂，其成分为Ca（OH）_2和脂肪酸，pH为中性，不产生上述沉淀。但我们发现，含Ca（OH）_2的根管封闭剂有两种不同的类型，即Ca（OH）_2-Ca（OH）_2-Ca（OH）_2-Ca（OH）_2-Ca（OH）_2）_2-Ca（OH）_2）_2-Ca（OH）_2）_2。

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.