Pulp capping is an operative technique designed to preserve the vitality of a potentially infected pulp. There are two broad types of pulp capping - the direct and the indirect pulp caps. They are only successful if the pulpal infection is very mild
We have put this topic into the endo section as, if you take the biological viewpoint for endodontology (study of the pulp in health and disease), we believe it belongs here more than in the "restorations" section.
Direct Pulp Cap
The exposed pulp is directly covered. This works best when the exposure is not infected - for example a traumatic exposure caused by slipping with the drill.
If the pulp becomes exposed while removing soft infected dentine, the chances are that the pulp will be infected also, and a direct pulp cap will fail (that is, an irreversible pulpitis will develop).
Although Calcium Hydoxide has been proven successful for many years, MTA (Mineral Trioxide Aggregate) is fast becoming the material of choice for direct pulp caps. MTA is however very expensive.
Indirect Pulp Cap
The pulp is not exposed - a layer of infected dentine is deliberately left, rather than expose the pulp.
Indirect pulp caps, when done correctly, are more succesful at maintaining long-term vitality than direct ones.
It is not currently (2014) known whether it is necessary to "go in again" after a couple of months for further caries removal.
Procedure for "stepwise" indirect pulp cap
Procedure for Direct Pulp Cap