| 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 mechanically 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 usingapparatus 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. |
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