2019 年 28 巻 4 号 p. 383-390
Although mineral trioxide aggregate (MTA) has excellent sealing properties and biocompatibility and is currently widely used in various applications including direct pulp capping, several problems associated with its use, such as variable curing time and inconsistent physical properties, persist. We have developed a chemically curable, resin-modified type of MTA material (PCX-TBB) using tri-n-butylborane (TBB) as a polymerization initiator to improve the abovementioned problematic characteristics. We previously reported that PCX-TBB exhibited good physicochemical properties, excellent calcium releasing ability, and enhanced hard tissue induction ability compared with those of TheraCal LC® (Bisco, Schaumburg, IL, USA), which is already used clinically. In the present study, we further clarified the biocompatibility and healing ability of PCX-TBB as a direct pulp capping material. The histopathological changes when PCX-TBB and TheraCal LC® were applied to the wound-exposed pulps of dogs were investigated. We evaluated the grade of inflammatory cell infiltration and state of dentin bridge formation 7 days and 69 days after the application of PCX-TBB and TheraCal LC®. It was found that the inflammatory changes in the repair of cavities via pulp capping using PCX-TBB were the same as those observed with the use of TheraCal LC®. The dentin bridges formed 69 days after the application of both the materials, and the use of PCX-TBB resulted in a greater extent of dentin bridge formation in each cavity than that achieved by TheraCal LC®. The dentin bridges formed with the use of PCX-TBB were greater in area than that of the largest dentin bridge formed using TheraCal LC® in at least 70% of the specimens. These findings suggest that PCX-TBB is more biocompatible and effective as a direct pulp capping material than TheraCal LC®.
