Toothpastes containing hydroxyapatite (HA-toothpaste) have demonstrated effcacy in preventing caries, treating hypersensitivity and curing periodontal diseases, however, their effects on whitening teeth have not been investigated. In this study, the polishing and whitening properties of hydroxyapatite contained toothpastes were evaluated in a combined experimental and clinical study. The polishing properties were evaluated in artifcial teeth by polishing with different toothpastes, while the brightening and whitening properties were examined in volunteers using two colorimeters with two specially made fberscopes. The results revealed that the addition of hydroxyapatite to toothpaste did not alter its polishing properties, while it did result in a marked increase in tooth-whiting. It was also found that the brightening and whitening properties increased as the amount of hydroxyapatite in the toothpaste increased. It is concluded that toothpaste containing hydroxyapatite are effective at whitening tooth and that whitening was not due to their polishing effect on tooth surface.

Hydroxyapatite is widely utilized as a component in dental hygiene agents. The ability to adsorb and remove dental plaque adhering to tooth surfaces is recognized as an important property of hydroxyapatite particles. In this study, the adsorptive ability of hydroxyapatite was evaluated based on its adsorptive amount and adsorptive strength. The adsorptive amount was determined by measuring the weight of albumin, dextran and lipids adsorbing to hydroxyapatite. The adsorptive strength was determined by measuring the weights of albumin and dextran remaining adsorbed after rinsing. Similar procedures were performed in control experiments using calcium hydrogen phosphate dihydrate, alumina and sericite. The results showed that the weights of albumin and dextran adsorbed to hydroxyapatite were 1.4

目的 用高效液相色谱法（HPLC）测定可吸收聚乳酸-替硝唑抗菌缓释剂中替硝唑的体外释放动力学，以观察聚乳酸-替硝唑共混缓释剂在作为抗牙周炎治疗剂时的药物持续释放时间和有效释放浓度。方法 采用C18色谱柱分离，以水-甲醇-冰醋酸为流动相，流速为1.5ml/min，测试波长为310nm，柱温为30℃，测定可吸收聚乳酸-替硝唑抗菌缓释剂中替硝唑的持续释放时间和有效释放浓度。结果 ①替硝唑的保留时间约为12min。②混合凝胶中替硝唑的浓度与峰面积呈良好的线性关系，方程：y=0.836+8.4522×10-5x（r=0.9986），线性范围为5～500mg/L，相对标准差为0.2%。③聚乳酸对替硝唑的测定无干扰。替硝唑平均每日释放度为5.60%，14d累计释放度约为78.40%。结论 聚乳酸-替硝唑共混缓释剂具有较长时间保持有效抑菌浓度的药物释放能力；HPLC是评价局部药物释放剂简便、准确和具有良好重复性的有效方法。

聚乳酸是一种很好的生物材料，具有很好的生物相容性及可降解性。在第一代聚乳酸膜的基础上我们研制了聚乳酸共混聚三亚甲基碳酸酯（PTMC）生物软膜，并对该复合材料进行了一系列的生物性能表征，包括细胞毒性实验、急性毒性实验、皮肤刺激实验、致敏实验、溶血实验、微核实验及皮下植入实验。结果表明，共混膜无毒，无刺激，无致敏作用，不引起溶血，试验材料组微核率为1.3%±1.0%，小于3%，骨髓微核实验呈阴性。皮下植入后各个时期伤口无红肿、化脓、坏死等现象。在应用于家兔术后预防肠黏连的实验研究中，生物软膜表现出很好的实验效果。结论:聚乳酸共混聚三亚甲基碳酸酯软膜具有很好的生物相容性。

目的 体外研究新型纳米羟基磷灰石（n-HA）根充糊剂的细胞毒性。方法 体外培养成骨细胞，采用碱性磷酸酶（ALP）和Ⅰ型胶原免疫组化染色鉴定成骨细胞；采用MTT 比色法，以F12培养基为对照，选用3种不同浓度的新型n-HA 根充糊剂浸提液，分别检测浸提液与成骨细胞接触1、3、5、7 d 的细胞相对增殖率（RGR），以评价其细胞毒性。结果 与对照组相比，新型n-HA 根充糊剂表现出较高的细胞相对增殖率，随着浸提液浓度的降低和培养时间的延长，细胞毒性趋于0级；相同时间点不同浓度的新型n-HA 根充糊剂浸提液的吸光度值无显著性差异（P>0.05）。结论 新型纳米羟基磷灰石根充材料无细胞毒性。