False negative pulp response seen in pulp testing in Endodontics

Electric pulp testing is a diagnostic technique used to diagnose the vitality of pulp in a tooth. With electric pulp testing a slight electric stimulus is given on the tooth surface which is coated by an electrolyte, the electrolytes used in electric pulp testing are: Nichollas-colloidal graphite, Grossman tooth paste.
The electric probe is used on the incisal 2/3rd of the labial surface of maxillary premolars and molars which is the most common location for electric pulp testing.

List of conditions showing false negative response:

1. Recently traumatized teeth
2. Recently erupted teeth with incomplete root formation
3. Teeth with extensive restoration and pulp protecting base
4. Patients under LA or sedatives.
5. Pulp stones
6. High amounts of reparative dentin in the tooth

List of conditions showing false positive response:

1. Moist gangrenous pulp, which requires maximum current to elicit the response
2. Presence of partially necrotic pulp in one of root canals in multirooted teeth

Note: Electric pulp testing is not useful on recently erupted tooth and teeth with immature apex. This is because of the lack of development of the relationship between the odontoblasts and the nerve fibers of the pulp.

Electric pulp responses to various pulp pathologies:

1. Irreversible pulpitis ia charecterized by pulpal necrosis and requires more current to elicit a response
2. Reversible pulpitis is charecterized by arterial hyperemia in which there will be increased amount of blood supply and the tooth responds for lesser amount of current then normal.
3. Chronic hyperplastic pulpitis or pulp polyp: Contains lesser nerve supply than normal pulp. So it also requires more amount of current to elicit a response.