Direct Pulp Capping with MTA

Young Bui, D.D.S.
Direct Pulp Capping with MTA

Young Bui

ECHANICAL pulpal exposure is inevitable when one excavates a large carious lesion. If the tooth is pretty much broken down and requires a crown, then root canal therapy should be done. But what would you do if the tooth were asymptomatic with a lot of tooth structure left before the excavation? Would you attempt to do a direct pulp cap to avoid root canal therapy for the patient? What pulp capping material should you use and how should you proceed?
    I was taught in dental school to do direct pulp capping in primary teeth. When it came to permanent adult teeth, I was told not to bother because the success rate was low unless the permanent was in a young person with incomplete root formation. In that case, direct pulp capping should be done in the hope that apexification would continue.
    Many articles have been written about pulp capping with MTA. Tziafas et al did a study to determine the early pulpal cell response after capping application of MTA in mechanically exposed pulps. “A homogeneous zone of crystalline structures was initially found along the pulp-MTA interface, while pulpal cells showing changes in their cytological and functional state were arranged in close proximity to the crystals. Deposition of hard tissue of osteotypic form was found in all teeth in direct contact with the capping material and the associated crystalline structures. Formation of reparative dentine was consistently related to a firm osteodentinal zone.” Aeinehchi et al found that pulp capped with MTA “demonstrated less inflammation, hyperaemia and necrosis plus thicker dentinal bridge and more frequent odontoblastic layer formation than calcium hydroxide.” Moghaddame-Jafari et al found that MTA induces proliferation and not apoptosis of pulp cells in vitro. And Chacko and Kurikose found that pulps capped with MTA showed dentin bridge formation which was more homogeneous and continuous with the original dentin when compared to the pulps capped with calcium hydroxide. All these studies suggest that MTA is a good material to use for direct pulp capping.
    A 43-year-old gentleman came in to see me on a Saturday morning regarding a large carious lesion on the mesial of tooth # 15. (See Figure 1.) He said that he would be out of the country for three months and was worried that the tooth might blow up on him. Examination showed that the tooth was asymptomatic and vital. The x-ray showed that there was a little bit of dentin separating the caries from the pulp. I excavated the decay using the # 8 round bur on a slow-speed handpiece. There was a little bit of pink showing by the time I removed all the decay. I went in and removed a little bit of the pulp horn to make sure that all the infected pulp, if any, had been removed. I irrigated the area with 2 percent lidocaine to remove the debris. I then mixed a little bit of MTA into a putty and applied it on top of the pulp. I used a moist cotton pellet to condense the MTA and also to remove some of the moisture. The cavity was closed with zinc phosphate cement. (See Figure 2.)


FIGURE 1: Showing a large carious lesion on the mesial of tooth # 15.	FIGURE 2: Showing the MTA cap and the cavity closed with zinc phosphate cement.

The patient was supposed to come back for an evaluation when he returned from his trip. That was back in January of 2002. He finally did come back on November 10, 2006, for a root canal on a different tooth. I took an x-ray of # 15 at that time and saw that there was now a thick layer of dentin bridge right below the MTA (Figure 3). There was no sensitivity to percussion, palpation, or chewing. The pulp was vital to the Endo Ice test with no inflammation. The only problem was that it had a large open contact space. I might have been lucky with the successful pulp capping in this case or maybe MTA is the next best thing. The only other direct pulp capping I did on an adult was on one of the dentists in our office. He had extensive decay, and the tooth was angulated so that access and proper isolation were very difficult. I did a pulpotomy on this tooth, placed MTA in the chamber, and restored it with amalgam. It has been asymptomatic ever since.

FIGURE 3: Showing a thick layer of dentin bridge right below the MTA.

July - August 2007

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