Development of Calcium Phosphate Cement as a Dual Cure Type Pulp Capping Agent

在将磷酸钙骨水泥(CPC)作为牙本质-牙髓复合体的直接盖髓剂应用中，需要使用一种牙本质粘结剂，在不破坏CPC的生物相容性和力学性能的情况下尽快完成固化。使用商用一步键合系统AQ Bond Plus[0！R]键合剂(AQP)作为液相。AQP为CPC提供了一种轻质固化机制，显著缩短了固化时间。然而，其凝结初期的机械强度和向羟基磷灰石(HA)的转化都低于通常的CPCs。这些结果表明，需要对聚合引发剂的单体类型和水分含量进行进一步的研究，以防止干扰HA的转化。然后，我们研究了CPC与不同的复合树脂粘接体系的粘接强度。结果表明，磷酸酯类粘接单体的粘接强度明显高于羧酸类粘接单体。这可能是因为-磷酸酯单体对无机成分的溶解能力比羧基单体更强，通过溶解CPC到达了深层。因此，有必要对CPC的力学性能、固化CPC的组成、化学反应中与粘结剂的区别等方面进行进一步的研究。因此，以CPC和AQP为液体制备的双固化型直接盖髓剂的实验促进了对CPC与树脂的粘接及其基本性能的了解。提示了本品在临床应用的可能性。

In the application of the calcium phosphate cement (CPC) as a direct-pulp-capping agent to the dentin-pulp complex, it is necessary to use a CPC that is dentin-adhesive, which completes the setting as soon as possible without spoiling the biocompatibility and the mechanical properties of CPC.We first attempted to develop a CPC as a dual cure-type direct-pulp-capping agent that possesses a light cure system in addition to the setting reaction. The AQ Bond Plus【○!R】 bonding agent (AQP), a commercial one-step bonding system, was used as the liquid phase. AQP provided CPC with a light setting mechanism, resulting in a marked reduction in the setting time. However, its mechanical strength in the initial stage of setting and its conversion to hydroxyapatite (HA) were lower than those of the usual CPCs. These results suggest that further investigation is necessary regarding the monomer type, and water content of the polymerization initiator, to prevent interference with the HA conversion.We then investigated the adhesive strength of the CPC with various composite resin adhesive systems. The results show that the phosphate ester adhesive monomers produce significantly higher adhesive strengths than the carboxylic adhesive monomers. This may be because the -phosphate ester monomers, whose ability of dissolution against inorganic components is stronger than that of carboxylic monomers, reached the deep part by dissolving the CPCs. Based on these results, therefore, it is necessary to conduct further investigation regarding the mechanical properties of CPC, the composition of the set CPC, the difference from adhesive agents in the chemical reaction, etc.Thus, these experiments with a dual cure-type direct-pulp-capping agent that was produced using CPC and an AQP as a liquid phase promote the understanding of the adhesiveness of CPC with resins and its basic properties. It also suggests the possibility of the clinical application of this CPC.