The aim of direct pulp capping is to protect the vital pulp which has been exposed during cavity preparation, either through caries or trauma. The most important consideration in obtaining success is that the pulp tissue remains uncontaminated. In deep cavities, when an exposure may be anticipated, all caries should be removed before approaching the pulpal aspect of the cavity floor. If an exposure of the pulp occurs in a carious field the chances of successful pulp capping are severely compromised. A rubber dam should be applied as soon as pulp capping is proposed. The pulp should be symptom-free and uninfected, and the exposure should be small. Before commencing large restorations in suspicious teeth it may be prudent to test the vitality of the tooth with an electronic pulp tester, and also to expose a radiograph to ensure that there is no evidence of pulpal or periapical pathology. The radiograph may in fact be more valuable, as misleading results may occur when using an electric pulp tester on compromised multirooted teeth.
If the above criteria have been met and pulp capping is indicated, the cavity should be cleaned thoroughly, ideally with sodium hypochlorite solution, and pulpal haemorrhage arrested with sterile cotton pledgets. Persistent bleeding indicates an inflamed pulp, which may not respond to treatment. After placing the calcium hydroxide, the area must be sealed against bacterial ingress, preferably with a glass-ionomer lining.