Pulp Capping is an operative technique designed to preserve the vitality of a potentially infected pulp.Pulp capping offers an alternative to root canal treatments.If the pulp becomes infected and the tooth dies, a root canal will be needed to save it from a tooth extraction. But if the tooth's nerve is still alive, pulp capping can be used to restrict the tooth decay from infiltrating the pulp chamber. Sometimes pulp capping is used as a preventive measure to keep a large tooth filling from getting too close to the nerve.

There are two broad types of pulp capping:
Direct Pulp Capping
Indirect Pulp Capping 

Direct Pulp Capping

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 Capping

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. 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. 

There are several reasons why you should go for pulp capping :
Saves the nerve and preserves the tooth. 
Less invasive than a root canal or extraction. 
Less recovery and sensitivity following the procedure. 
Costs less than a root canal.

Pulpotomy :

A healthy tooth has a space inside it called the "pulp space" which is filled with soft tissues - nerves, blood vessels and pink connective tissue. If a tooth gets a large cavity, the bacteria in the decay can damage the pulp, which is often what causes toothache.
Pulpotomy refers to coronal removal of the vital pulp tissue. In a tooth there is the crown part and the root part. In the crown part there is coronal pulp and in root there ia root pulp. Some times the cavity is deep but the pulp is not infected or there is pin point exposure but infection is not there.
In such cases it is recommended to remove the coronal pulp and save the root pulp. In this way the vitality of the tooth is maintained.

The objective is to remove the inflamed part of the pulp which is followed by the application of calcium hydroxide to the remaining pulp tissue