摘要
背景：直接盖髓术是一种符合生物学原理的活髓保存方法，人们在对其机理的进行探讨的同时也进行着盖髓剂的研究，对于盖髓剂所应具备的一些性能是大家已经公认的，关键在于去寻找一种符合这些性能条件的制剂。氢氧化钙类的盖髓剂统治牙髓治疗近半个多世纪，现在临床上使用最广泛的直接盖髓制剂代卡尔(Dycal)、钙为他(Calvital)等大多是以该类药物为主的制剂。同时还有其他类的制剂如生物类的试剂，激素及抗生素制剂等，但这几类盖髓剂还只是处于研究阶段，临床疗效尚未最后确定。目前国外通过大量的基础研究研制出一种符合盖髓剂所应具备的一些性能，同时又克服了上面所述制剂的一些缺陷的制剂Mieral Trioxide Aggregate(MTA)，并将其应用在临床上取得了好的盖髓效果。本次实验用其来覆盖狗牙的机械性穿髓面，以进一步证实该制剂的盖髓疗效。
目的：观察用MTA直接覆盖因机械性露髓的狗牙的牙髓细胞反应、修复性牙本质的形成、组织的分解及盖髓成功率。
方法：将四只狗的80颗牙分成两组(实验组40颗和对照组40颗)，用特制的穿髓器械在狗牙上备V类洞并使髓腔暴露，分别用MTA和氢氧化钙覆盖露髓面，用玻璃离子体填充窝洞。在光镜下观察不同时段(2周和8周)组织学切片的牙髓组织反应。
结果：2周时，实验组20颗中有16颗狗牙露髓处有修复性牙本质的形成，2颗形成完整的牙本质桥且髓腔中未见炎症细胞浸润；4颗失败牙的组织切片中未见髓腔组织分解。对照组20颗牙中有3颗牙盖髓成功，仅1颗有完整的牙本质桥形成，在其失败的组织切片中可见髓腔细胞变性或坏死或成空腔。
8周时，实验组20颗牙中有19颗显示成功，其中n颗无炎症细胞浸润，
9颗有完整的牙本质桥形成覆盖髓腔;刘一照组20颗牙中有12颗牙成功，其
中5颗牙本质桥形成并封闭创面，其它仍见不等量的炎症细胞浸润牙髓，失
败组织切片中有脓肿、细胞变性、髓腔组织分解等。
结论:①将MTA用于直接盖髓，其良好的密封性能使之在早期较氢氧
化钙更具有抗感染作用，从而提高其直接盖髓的疗效。②具有比氢氧化钙更
强的诱导作用，能够诱导机械性穿髓牙的早期修复性牙本质形成，为牙髓自
身的修护作用的发挥创造了良好的环境。③MTA在直接盖髓后，可观察到
修复性的牙本质桥的形成，2周后的盖髓成功率为80%，8周后的盖髓成功
率为95%，MTA是一种效能肯定的盖髓剂。
Background: Direct pulp capping is a kind of biological method to keep the involved pulp alive and healthy. For a long time studies have been undertaking the research on the mechanism of pulp capping and the pulp capping agents as well. The requirements of pulp capping agents have been well-known, but the most urgent work is still to find out an agent which can satisfy all the requirements .The agents such as Dycal and calvital which contain Calcium Hydroxide have dominated most area of pulp capping. And other agents such as biological agents, hormones and antibiotics have less effective results when used in pulp capping. Mineral Trioxide Aggregate (MTA), which is a new product for pulp capping, based upon much basic research work, can overcome the drawbacks of other old agents, satisfy most of the requirements of pulp capping agents and has been used in clinic, achiving optimal results. This experiment is to further verify the effects of MTA as a sort of pulp capping agent through using it on the mechanical
ly exposed pulp of dog teeth.
Objectives: The objective of the present experiment was to study the dog pulpal cell responses and the onset of reparative dentine formation after the direct application of MTA to mechanically exposed pulps.
Materials and methods: Eighty teeth divided into two groups from four dogs, 12-18 months of age were mechanically exposed via class V cavities using
apparatus made specially. Light pressure was applied to control haemorrhage.
ProRoot MTA or Calcium hydroxide were placed at the exposure site and light pressure was applied with a wet cotton pellet. The cavities were restored with glass ionomers and the pulpal tissue reactions were assessed by light microscopy after healing intervals of 2 or 8 weeks.
Results: The reparative dentin formation can be seen at the pulp exposure site of the 16 dogs' teeth in experimental group after2 weeks. 2 of the teeth have the complete dentin bridge without inflammation infiltration. There was no pulp dissolution in the failure slides.3 dog teeth in control group have the successful pulp capping, but only one has the complete dentine bridge formation, also we can see the degeneration and necrosis of the pulpal cells in the failure slides. 19 teeth in experimental group have the successful results after 8 weeks, 9 of them have the complete dentine bridge formation without inflammation. 12 teeth in control group were successful, and 5 of them had the dentine bridge which had sealed the pulp wounding surface, the rest teeth had get the infiltration of more or less inflammation cells. There was also abcess, degeneration and tissue dissolution in the failure slides.
Conclusions: (1)MTA that has been used in direct pulp capping has no less anti-bacteria effects than Calcium Hydroxide, and has more unti-infection function than because of its better hermatic ability, which will surly improve the clinic effect of direct pulp capping. (2)MTA has more inducing function than Calcium Hydroxide, which can induce the early reparative dentin formation in the mechanically exposed pulp and ensuringly creat an suitable environment for pulp to restore itself. (3)Reparative dentine bridge can be seen formed after direct pulp capping of MTA ,the success rate of which is 80% two weeks later and 95% 8 weeks later. MTA is surely a variety of effective pulp capping agent.
引文
1 樊明文主编《牙体牙髓病学》．北京：人民卫生出版社2000年
2 Webber RT. Apexogenesis veraus apexification Dent Clin North American. 1984.28(4):669-97
3 王满恩、王嘉德 主编译《牙髓病的生物学基础》北京医科大学、中国协和医科大学联合出版社 1991年
4 Schroder U. Effects of calcium hydroxide-containing agent on pulp cell migration, proliferation and differentiation. Journal of Dental Research. 1985, 64,541-8.
5 Cvek M,Granath L,Cleaton-jones P,Austin J. Hard tissue barrier formation in pulpotomized monkey teeth capped with cyanoacrylate or calcium hydroxide for 10 and 60 minutes. Journal of Dental Research. 1987, 66,1166-74.
6 二木什人，象牙质削片应用仁生活齿保护效果仁关临床病理学的研究，齿科学报，1979，79：25
7 韩永战，史俊南 用于活髓保存治疗的生物材料．牙体牙髓牙周病杂志，1994，12(2)：121
8 Schmitt D,Lee J,Bogen G. Multifaceted use of ProRoot MTA root canal repair material.Pediatr Dent,2001, 23(4):326-30.
9 HollandR,deSouza.V,Nery MJ,FaracoJunior IM,Bernabe PF,OtoboniFilho JA,Ddezan Junior E. Healing process of dog dental pulp after pulpotomy and pulp covering with mineral trioxide aggregate or Portland cement. Braz Dent J 2001;12(1):3-8
10 Tziafas D,Pantelidou O,Alvanou A., Belibasakis G. & Papadimitriou S.The dentinogenic effect of mineral trioxide aggregate (MTA) in short-term capping experiments. Int J Endo,2002, 35,245-254.
11 Josimeri Hebling,, Elisa Maris Aparecida Giro & Carlos Alberto de Souza Costa. Biocompatibility of an adhesive system applied to exposed human dental
pulp. Journal of Endodontics 1999, 25(10): 676-82.
12 Mitchell PJC, Pitt Ford TR, Torabinejad M, McDonald F Osteoblast biocompatibility of mineral trioxide aggregate. Biomaterials. 1999, 20,167-73.
13 Torabinejad M, Hong CR, McDonald F, Pirr Ford TR PHysical and chemical properties of a new root-end filling material. Journal of Endodontics. 1995, 21,349-53.
14 Torabinejad M, Chivian N Clinical applications of mineral trioxide aggregate. Journal of Endodontics.1999, 25,197-205.
15 五十岚胜，日齿保志 1989，32(6)：1706．
16 原泰司，日齿保志 1988；31(3)：885．
17 五十岚胜，日齿保志 1984；27(4)：769
