2TheApex: Asymptomatic vital tooth, isolation, coronal seal, and a bio compatible material are the keys to a direct pulp cap.

Tooth status:  Asymptomatic carious exposure or recent trauma, no history of symptoms suggesting irreversible pulpits, and an an incompletely formed apex.  

Pulp testing should be done prior to anesthesia. Prognosis of a direct pulp cap from a carious exposure in a mature tooth is very poor and often leads to more problems in the future.

Isolation: Rubber dam isolation is very important, saliva contamination will cause bacteria to be introduced to the site.  NaOCl soaked cotton pellet should placed gently but firmly on the exposed pulp to decontaminate the area and control bleeding.  Persistent and excessive bleeding is a sign of inflammation and likely irreversible pulpitits.  A pulp cap should not be attempted in this situation.

Bio compatible material:  MTA or other bioceramic material is the preferred.  Traditionally CaOH has been used, however this is less biocompatible and will eventually break down.

Seal:  The seal is the deal! Coronal leakage will invariably lead to pulpal pathosis.  We recommend placing thin layer of Vitrebond directly over the pulp cap material, then proceed with a bonded final restoration immediately. 

Manage expectations:  Inform patient of the possibility that root canal treatment may still be necessary.