Influence of temperature on volumetric shrinkage and contraction stress of dental composites

OBJECTIVES:
To test the influence of temperature on contraction stress and volumetric shrinkage of Clearfil AP-X, Venus Diamond, Premise and Filtek Z250.

METHODS:
Volumetric shrinkage measurements were carried out using mercury dilatometry, while a constraint tensilometer set-up was used for the measurement of contraction stress. Measurements were carried out with a composite temperature of 23, 30, 37, and 44°C.

RESULTS:
Volumetric shrinkage increases with higher temperature. Premise and Venus Diamond show lower volumetric shrinkage than Clearfil AP-X and Filtek Z250. Clearfil AP-X shows the highest contraction stress which slightly increases with higher temperatures. The other composites only show an increase in contraction stress between 23 and 30°C.

SIGNIFICANCE:
Heating of dental composites results in a higher volumetric shrinkage. However, the contraction stress does not change significantly due to increased temperature above 30°C.