Pulpal reactions to two experimental bonding systems for pulp capping procedures

This study evaluated the pulpal responses induced by application of two types of bonding system to the exposed dental pulp. One consisted of the following steps: etching with neutralized EDTA, application of an experimental water-based photocuring bonding agent, and restoration with a commercially available photocuring resin composite (EDTA etching system). The other was treatment with an experimental water-based self-etching primer, application of a commercially available bonding agent, and restoration with a commercially available photocuring resin composite (self-etching system). These two systems of treatment were applied to the exposed pulp. Calcium hydroxide was used as a control for the direct pulp-capping material. The pulps in class V cavities in the anterior teeth of beagles were mechanically exposed and then filled using the etching, the self-etching, or the Ca(OH)2 system. The beagles were sacrificed on the 7th, 30th or 90th postoperative day, and pulpal responses were investigated histopathologically using light microscopy. The EDTA etching system induced severe pulp reactions at 7 days after the operation. These reactions did not completely diminish after 90 days. Reparative dentin formation was observed at day 90. The self-etching system showed moderate pulp reactions, which gradually decreased over the experimental period. Reparative dentin bridge formation was observed at day 90. No necrosis of the pulp was observed at any time. Calcium hydroxide induced both moderate and severe initial pulp reactions, with reparative dentin formation evident at day 30. Necrosis was observed in the superficial pulp. It is suggested that the EDTA etching agent caused not only pulpal damage but also re-bleeding because of rinsing and drying. The self-etching system is a promising system for direct pulp capping.