Temperature change in pulp cavity in vitro during the polymerization of provisional resins

Objectives. To measure the temperature change in the pulp cavity of an extracted tooth during
the polymerization of provisional resins within impression putty and polyethylene matrices.
The effect of precooling
the putty matrix was also evaluated.
Methods. A freshly extracted premolar tooth had putty impressions recorded prior to crown
preparation. Putty matrices were stored at room temperature, 4 and −12 C prior to use. A
thermocouple placed in the pulp chamber recorded the temperature change every 15 s for
a 10min
duration during polymerization of three resins using putty and clear polyethylene
matrices. Five recordings were made with each material at each storage temperature.
Results. There is a temperature rise of 3.4–5.5 C when the resins were autocured in a putty
matrix. When the polyvinyl matrix was used the temperature rise increased to 4.0–8.2 C
(P < 0.001). The temperature rise was reduced to zero when the putty had been precooled
in the fridge (P < 0.001) and reduced further following precooling
in the freezer (P < 0.001).
Significance. The use of a polyvinyl matrix allows higher pulp temperature rises to occur due
to the exotherm from provisional resins. Lower temperatures were recorded when putty
was used. The temperature rise could be eliminated when the putty was cooled at 4 C prior
to reinsertion.