Effect of CO2 Laser Irradiation and Direct Pulp Capping using Experimentally Developed High Molecular Pulp Capping Agents: the Wound Healing Mechanisms of Exposed Pulp.

作为修复性牙本质促进剂，将四种类型的磷酸钙：羟基磷酸钙、磷酸氢钙(刷石：DCPD)、β-磷酸三钙(白云石：β-Tcp)和磷酸八钙(OCT)与实验单体液混合，制成实验研制的直接盖髓剂和牙基粘结剂。采用扫描电子显微镜、电子探针和电感耦合等离子体原子发射光谱仪对聚合后的磷酸钙的分散性、形貌和组成进行了分析，结果表明：1)聚合后的单体溶液中的磷酸钙粉末呈分散状分散在复合树脂中。在原料的混合制备过程中，振动和研磨对粉末的分散性有很大的影响。2)钙相对于磷的浓度相对较高，但镁只以微量存在，只有在使用直线分析时才能检测到。3)每个钙磷…更多的TE表现出不同的钙和磷洗脱能力，洗脱量受每种钙磷酸盐的溶度积(KSP)的影响。4)实验结果表明，作为直接盖髓材料，修复性牙本质的形成和创面愈合的可靠性有望提高，尤其是在盖髓后的第一阶段。5)聚合的盖髓和粘结剂中的磷酸钙存在于暴露的牙髓附近。在直接接触促进钙化、磷酸钙洗脱出的钙磷离子效应和pH变化影响裸露牙髓表面环境变化的条件下，有效地促进了修复性牙本质的形成。用实验用底物和12种粘结剂联合对暴露的大鼠牙髓进行直接盖髓。直接盖髓后，分别于实验第1、3、7、14、28d处死大鼠。结果如下：1)术后第1天，各组均有轻度炎症改变，但随着时间的推移(3、7天)逐渐减轻。2)在不使用磷酸钙组中，第14天几乎没有观察到修复性牙本质的形成，但在第28天观察到少量的修复性牙本质形成。3)在使用磷酸钙组中，在第14天已经可以观察到修复性牙本质的形成，并随着时间的推移而增加，直到第28天。4)修复性牙本质的形成明显受磷酸钙的种类和浓度的影响。5)在含有磷酸钙组中，MB5(β-TCP5wt%)、MB9(HAP5wt%，β-TCP5wt%)、MB1(HAP5wt%)、MB2(HAP10wt%)和MB3(β-TCP5wt%)组的修复性牙本质形成相对较多。6)在实验开发的引物中，β(MB引物含5-NMSA 2wt%)比另一种含有抗菌单体MDPB的实验引物(ABPMDPB)表现出更少的炎症变化。MB1和MP3的联合应用显示正牙本质中炎症改变最小，修复牙本质最先进。提示MB1和MP3联合应用是直接盖帽后第一阶段创面愈合最可靠的方法。在CO_2激光照射组，使用了S II SP(吉田牙科Mfg公司)。炭化后，直接在牙髓表面覆盖MB。结果如下：1)炭化后第1天，牙髓表面炎性改变稍重。但随着时间的推移，它们消失了。2)没有观察到修复性牙本质的形成，即使在14.3天后也几乎没有观察到修复性牙本质的形成，即使在第28天也是如此。4)牙髓碳化层下可见不规则类型的牙本质基质形成。5)牙本质壁的照射区域表现为：碳化层、苏木素染色良好的坏死层和曙红染色良好的蛋白质变性层。6)激光照射引起的碳化和坏死层阻碍了牙本质的修复形成和延迟了牙髓的伤口愈合。两层都不起到隔离外界刺激的作用，也没有起到保护牙髓的作用。7)采用的照射条件如下：轻度、中度、具有LLLT效应和较强的水平。用CO_2激光对四种实验研制的含有磷酸钙的直接盖髓剂和粘结剂(MB8、MB9、MB11和MB12)和一种实验研制的底漆(MP)进行了检测。两组之间没有显著差异，证实了轻度照射显示出牙髓的快速愈合特性，并形成了相对较好的修复性牙本质质量。8)由于中等照射水平的掩蔽效应，CO_2激光的LLLT效应未得到明确证实。关于CO_2激光的辐照条件，还需要进一步的研究。较少

As reparative dentin-promoting agents, four types of calcium phosphates: hydroxyl-calcium phosphate (HAP), dicalcium phosphate dehydrate (brushite : DCPD), beta-tricalcium phosphate (whitrokite : β-TCP) and octacalcium phosphate (OCT), were mixed with experimental monomer liquid to create materials for experimentally developed direct pulp capping agents and bonding agents of dental substrates. After polymerization, dispersion, shape and composition of calcium phosphates were analyzed by using SEM, EPMA and ICP Atomic Emission Spectrometry.Results obtained were as follows :1) The powder of calcium phosphates in polymerized monomer liquid scattered like dispersed fillers in composite resin. The dispersion of the powder was highly influenced by vibration and trituration during the mixing preparation of the materials.2) Ca showed a relatively high concentration in relation to P. But Mg was present only in a trace amount and was detected only when using line analysis.3) Each calcium phospha … More te showed different elutions of Ca and P. The amount of elutions was affected by the solubility product (Ksp) of each calcium phosphate.4) It was suggested that when the materials were used as direct pulp capping agents, reparative dentin formation was particularly promoted and reliability of wound healing was expected to increase, especially improvement of wound healing in the first stage after capping.5) Calcium phosphates in polymerized pulp capping and bonding agents were found in the vicinity of the exposed pulp. Reparative dentin formation was effectively promoted under the following conditions: calcification promoting effect by direct contact, ionic effect of Ca and P eluted from calcium phosphates and environmental change of the surface of the exposed pulp through the effect of the change in pH.In total twelve types of bonding agents were prepared at a fixed amount of calcium phosphates. The exposed pulp in rats were directly capped with combined use of experimental primers and twelve types of bonding agents. After direct capping of exposed pulp, the rats were sacrificed at the experimental periods of 1, 3, 7, 14 and 28 days. Inflammatory and reparative pulpal changes were examined immunohistochemically and histopathologically under an optical microscope.Results could be summarized as follows :1) After day one, mild inflammatory changes were observed in all groups but they decreased over time (3, 7 days).2) In the groups which used no calcium phosphates, almost no reparative dentin formation was observed on day 14 but a little was observed on day28.3) In the groups which used calcium phosphates, reparative dentin formation was already recognized on day 14 and increased over time up to day 28.4) Reparative dentin formation was clearly affected by the types and concentrations of calcium phosphates. In addition, differences were also observed between the primers.5) In the groups containing calcium phosphates, relatively more reparative dentin formation was observed in the following groups: MB5 (β-TCP 5wt%), MB9 (HAP 5wt%, β-TCP 5wt%), MB1 (HAP 5wt%), MB2 (HAP 1Owt%) and MB3 (β-TCP 5wt%). In general, the groups containing β-TCP showed more advanced reparative dentin formation.6) In experimentally developed primer, MP3 (MB primer containing 5-NMSA 2wt%) showed less inflammatory change than another experimental primer (ABP) containing the antibacterial monomer MDPB. The combination use of MB1 and MP3 showed the least inflammatory change and the most advanced reparative dentin in orthodentin. It was suggested that the combination use of MB1 and MP3 was the most reliable for wound healing in the first stage after direct capping.In the CO_2 laser irradiation groups, Opelaser^<【○!R】> 03 S II SP (Yoshida Dental Mfg Co) was used. After carbonization, the pulpal surface was directly capped with MB.Results could be summarized as follows:1) After day one, slightly stronger inflammatory changes were observed. But they disappeared over time.2) No reparative dentin formation was observed, even after day 14.3) Almost no reparative dentin formation was observed, even after day 28. Instead large amounts of irritative dentin formation was observed on the pulpal wall.4) An irregular type of dentin matrix formation was recognized under the layer of pulpal carbonization.5) The irradiated area of the dentin wall showed the following layers : a carbonization layer, a necrotic layer dyed well with hematoxylin, and a protein denaturation layer dyed well with eosin.6) Carbonization and necrotic layers induced by laser irradiation obstructed reparative dentin formation and delayed wound healing of the pulp. Neither layer worked as an isolation layer from outside stimulation nor as a protective layer of the pulp.7) Irradiation conditions employed were as follows: mild, moderate with an LLLT effect and strong levels. Four types of experimentally developed direct pulp capping agents and bonding agents containing calcium phosphates (MB8, MB9, MB11 and MB12) and an experimentally developed primer (MP) were examined with and without irradiation using a CO_2 laser. There were no significant differences between the groups, and it was confirmed that a mild level of irradiation showed fast would healing properties of the pulp and formed a relatively better quality of reparative dentin.8) By a masking effect at a moderate level of irradiation, an LLLT effect of the CO_2 laser was not clearly confirmed. Regarding the irradiation conditions using the CO_2 laser, more studies are required in the future. Less