Journal of Dental Research, Vol 73, 1684-1689, Copyright © 1994 by International & American Associations for Dental Research Online Journals
An investigation into the pressure transmitted to the pulp chamber on crown cementation: a laboratory study
S. G. Wylie and P. R. Wilson
School of Dental Science, University of Melbourne, Australia.
Pressure changes in the pulp chamber resulting from crown cementation have
not been previously quantified. An experiment was designed to investigate
the effect of smear layer removal on the peak pressure transmitted to the
pulp chamber with crown cementation. Ten matched pairs of single-rooted
premolar teeth were collected from adolescents and prepared for
full-coverage crowns. The pulp tissue from each tooth was removed. One
tooth from each pair had the smear layer removed with the application of
37% phosphoric acid for 30 s. The null hypothesis states that the removal
of the dentinal smear layer will not change pressure in the pulp chamber
resulting from the cementation. Before cementation, a hydrostatic head of
pressure was used to perfuse the tooth, and the perfusion rate was
recorded. Crowns were cemented with zinc phosphate cement with a seating
force of 100 N. The mean peak pressures recorded were 85 Pa (SE 12 Pa) with
the smear layer intact, and 194 Pa (SE 49 Pa) when the dentin was etched.
The difference in the peak pressures transmitted to the pulp chamber with
the two groups was significant (p < or = 0.05). A significant negative
correlation was found between dentin thickness and the peak pressure
transmitted to the pulp chamber (r = -0.5531, p < or = 0.01). We have
shown that the pressure transmission to the pulp chamber during crown
cementation can be measured. Since smear layer removal significantly
influences the peak pressure, it is concluded that the pressure detected is
at least partially dependent on the fluid flow through the dentin.
