2. In young patients the A-delta fibres, which respond to the EPT, are not fully developed, therefore a negative response may be recorded from a vital tooth.
3. The presence of saliva on the tooth can conduct the current to the adjacent teeth and gingival tissues, giving a positive response that does not originate from the tooth being tested.
4. Large restorations or thick linings may prevent the current from stimulating pulpal nerve tissue.
5. Molar teeth may have a combination of vital and non-vital canals and a positive reading will be recorded even though a canal is necrotic.
6. Teeth involved in splints or as part of a bridge may give a positive response as the electric current is transferred to adjacent vital teeth.
7. Tooth wear can lead to large areas of sclerotic dentine that may give a negative response although the tooth is vital.
8. Following trauma, the pulp may give a negative response because of temporary paraesthesia of the nerve fibres. If the tooth remains vital a positive neuronal response should occur within 30–60 days.
9. Ref. Restoration of the root-filled tooth: pre-operative assessment. BRITISH DENTAL JOURNAL VOLUME 198 NO. 7 APRIL 9 2005
