: Dental pain evoked by hydrostatic pressures applied to exposed dentin in man: a test of the hydrodynamic theory of dentin sensitivity

By Ahlquist M, Franzen O, Coffey J, Pashley D

Date: 01/1994
Journal: JOE


Investigate the hydrodynamic theory


N = 4 paid voluntary subjects planned for extraction due to periodontal disease.

  • Before Treatment: sensitivity tested using EPT & cold by ethyl chloride to verify pain can be evoked.
  • Tooth anesthetized w/ 3% mepivacaine. Small cavity prep made. Contraption to allow administration of positive and negative pressures. Pain intensity measured using finger span device (0-100).
  • Hydrostatic pressures applied to (1) cavities in the presence of smear layer, (2) removal of smear layer with EDTA, (3) dentin tubules closed with 3% oxalic acid (topical application that forms calcium oxalate within dentinal tubules), and (4) removal of calcium oxalate by EDTA.


  • Pain perception:

A.Presence of smear layer = no pain

B.Removal of smear layer = distinct sensation of pain

C.Presence of oxalic acid = no pain

D.Removal of oxalic acid = weak pain (prob some residual calcium oxalate is present)

  • Faster changes in hydrostatic pressure evokes a higher pain intensity than slower rates of pressure changes.

Clinical Significance:

Supports the hydrodynamic theory of dentin sensitivity