Objective: To investigate the effects of pulpitis on pain evoked by cold and osmotic stimuli.
Method: Dentine was exposed at the tip of the buccal cusp in 9 pairs of healthy premolars in 9 subjects. The cavity was etched and filled with saline. Dentine was stimulated by applying either saturated CaCl2 or 5°C saline. Subjects indicated the intensity of any pain produced on a 100 mm visual analog scale (VAS). The cavity was then filled with either gutta percha (GP), which leaks and induces pulpitis or, in contra-lateral controls, GP sealed with glass ionomer material (GI). After one week, the filling was removed and both stimuli repeated. At each stage, laser Doppler records of pulpal blood flow were obtained.
Result: Filling with GP increased the pain evoked by both cold and osmotic stimuli. The mean VAS scores increased significantly (P<0.05, paired t test) from 17.7 ± 18.8 (s.d.) to 44.6 ± 38.0 and from 34.9 ± 29.7 to 59.6 ± 38.9 respectively. Pulpal blood flow similarly increased significantly from 1.5 ± 1.2 to 2.9 ± 1.8 P.U. In the control teeth, both pulpal blood flow and the pain produced by cold were unchanged but the mean VAS score with the osmotic stimulus increased significantly from 29.4 ± 24.0 to 50.4 ± 39.4 mm
Conclusion: The results with cold stimuli are similar to those of the earlier study. The differences between the results with cold, osmotic and hydrostatic-pressure stimuli may be due to different receptor systems being involved or to changes in hydraulic conductance along the dentinal tubules following cavity preparation and pulpitis.