Larsen M J, Hörsted-Bindslev P
Royal Dental College, Faculty of Health Sciences, University of Aarhus, Vennelyst Blvd., DK-8000 Aarhus C, Denmark.
Int Endod J. 2000 May;33(3):238-42. doi: 10.1046/j.1365-2591.2000.00279.x.
The aim of the present study was to describe pH changes in a variety of buffering solutions within a narrow test tube containing either a gutta-percha point with incorporate calcium hydroxide, a commercial calcium hydroxide paste (Calcicur) or a freshly mixed paste of calcium hydroxide in distilled water.
The test material was placed centrally in a test tube of 2 mm inner diameter. Saline (1%) was placed at one end, whilst the buffering solutions were introduced at the other. The pH of the buffering solutions was monitored using electrodes placed at each end of the test tube.
It was found that the pH 4.01 buffer strongly resisted pH changes at levels below 6.0, whilst saliva and bovine serum was buffered less and more evenly in the whole range up to pH 11.5. The calcium hydroxide containing gutta-percha points caused the pH to increase quickly in the sodium chloride solution to levels above 11.5. However, in bovine serum, in saliva and in the pH 4.01 buffer the pH remained below 8.5, 8.0 and 6.0, respectively, 1 mm from the point. In contrast, the release of hydroxyl ions from the two calcium hydroxide pastes brought pH above pH 11.5 irrespective of the buffering of the solutions 5 mm from the paste.
It is concluded that Calcicur and the calcium hydroxide-water mixture contained substantially more available calcium hydroxide than did the calcium hydroxide containing gutta-percha points, with the result that the release of hydroxyl ions from the points was limited in comparison to that from the pastes.
本研究的目的是描述在一个狭窄的试管内，含有加入氢氧化钙的牙胶尖、市售氢氧化钙糊剂（Calcicur）或蒸馏水新混合的氢氧化钙糊剂的各种缓冲溶液中的pH变化。
将测试材料置于内径为2mm的试管中央。一端放置生理盐水（1%），另一端引入缓冲溶液。使用置于试管两端的电极监测缓冲溶液的pH值。
发现pH 4.01缓冲液在pH值低于6.0时能强烈抵抗pH变化，而唾液和牛血清在pH值高达11.5的整个范围内缓冲作用较小且更均匀。含氢氧化钙的牙胶尖使氯化钠溶液中的pH值迅速升高至11.5以上。然而，在牛血清、唾液和pH 4.01缓冲液中，距离牙胶尖1mm处的pH值分别保持在8.5、8.0和6.0以下。相比之下，两种氢氧化钙糊剂释放的氢氧根离子使pH值高于11.5，而与距离糊剂5mm处溶液的缓冲作用无关。
得出结论，Calcicur和氢氧化钙-水混合物所含的有效氢氧化钙比含氢氧化钙的牙胶尖多得多，结果是与糊剂相比，牙胶尖释放的氢氧根离子受到限制。
