Light and scanning electron microscopy of the inner surfaces of resins used in direct pulp capping

Purpose: To investigate with the scanning electron microscopy (SEM) the inn er surface of the resin restorative used as a direct pulp capping, Material s and Methods: Class V cavities were prepared on the facial surfaces of 90 intact monkey teeth, and the pulps were intentionally exposed with a carbid e bur through the cavity floor. Each exposed pulp was capped with one of th ree commercially available adhesive resin systems (BondWell LC, GC; Imperva Bond, Shofu; Clearfil Liner Bond II, Kuraray). The cavities were restored with an adhesive resin and a hybrid resin-based composite. Histopathologica l changes of the mechanically exposed pulp were evaluated at 3, 30 and 60 d ays postoperatively. The interface between the resin and pulp tissues on th e inner surface of the resin restorative was observed by SEM. Results: Bact erial penetration along the cavity walls and pulp tissue could not be detec ted in any specimen. Slight inflammatory cell infiltration was the main ini tial reaction, while dentin bridge formation was the major long-term reacti on in all groups. The resin surface adjacent to the etched cavity floor con tained numerous resin tags corresponding to the dentin tubules. Remnants of pulpo-dentin complex, such as fragments of blood clots, pulpal cell, and d entin were also seen scattered along the inner resin surface.