 Practices were assigned by chance into one of two treatment groups, those that completed direct pulp capping with mineral trioxide aggregate and those that completed direct pulp capping with calcium hydroxide, both FDA approved agents for this purpose. The handling characteristics of the two materials were so different, that it was not practical to blind the practitioners as to which material they were using. Likewise, training in the use of each material was required. It was believed that it was more important that the practitioner become familiar and competent in the use of one of the materials to ensure it was used appropriately, than it was to have practitioners use both materials and confuse procedures between them. Since time was a critical element in the success or failure of direct pulp capping, the patients were consented to participate in the study after the procedure was done. A resin-modified glass ionomer liner e.g. Vitrebond, Fuji Lining Cement, Fuji II LC, Vitremer was placed over the pulp capping agent. This liner sealed the pulp capping agent and protected the pulp from being infiltrated with bacteria. After the resin-modified glass ionomer lining material was set, the final filling was placed. 