Research Update: Use of MTA for Direct Pulp Capping

In a recent post, we have discussed the use of MTA as a pulp capping agent.

A recent article by Yasuda, Ogawa, Arakawa, Kadowaki and Saito entitled "The Effect of Mineral Trioxide Aggregate on the Mineralization Ability of Rat Dental Pulp Cells: An In Vitro Study" may shed some light on the reasons MTA may be more effective than calcium hydroxide for direct pulp capping.

Direct pulp capping is an effort to maintain the vitality of a dental pulp following exposure during excavation and thereby avoid endodontic therapy. The formation of a dentinal bridge over the exposed pulp surface is the goal while maintaining pulpal vitality.

Conventional pulp capping treatment included medicating the exposed pulp with calcium hydroxide (ie. Dycal) prior to restoration. Calcium hydroxide is known to cause an inflammatory reaction of the dental pulp. Appication of adhesive resins has also been attempted. Incomplete dentinal bridges has been found with a lack of published long term clinical results.

It has been reported that MTA induces the formation of dentinal bridging with little or no inflammation. MTA is known for it's biocompatibility and lack of cytotoxicity. Tani-Ishii et. al. reported that MTA upregulated the expression of type I collagen and osteocalcin in osteoblasts.

Bone morphogenic proteins (BMP's) are crucial to bone and collagen formation. BMP-2 and it's receptor are expressed in the dental pulp. BMP-2 has been shown to accelerate the differentiation of human pulp cells into odontoblasts. This study hypothesized that BMP-2 is involved in the MTA induced mineralization.

This study found that MTA significantly stimulated mineralization (in rat dental pulp cells) by 60% compared to the controls. MTA and Dycal both significantly upregulated by 2-fold the level of BMP-2 mRNA compared with the controls. MTA increased the BMP-2 protein production by 40% while Dycal significantly reduced it. The authors suggest that BMP-2 may play an important role in mineralization stimulated by MTA.

MTA has shown promise as a direct pulp capping agent which may improve the success of direct pulp capping over convention calcium hydroxide techniques.

Sources:
Yasuda, Ogawa, Arakawa, Kadowaki, Saito. "The Effect of Mineral Trioxide Aggregate on the Mineralization Ability of Rat Dental Pulp Cells: An In Vitro Study". JOE 2008; 34:1057-1060.

Tani-Ishii, Hamad, Watanabe, Tujimoto, Teranaka, Umemoto. "Expression of Bone Extracellular Matrix Proteins on Osteoblast Cells in the Presence of Mineral Trioxide". JOE 2007; 33:836-839.