Assessment of Degree of Conversion and Volumetric Shrinkage of Novel Self-Adhesive Cement

Abstract

The degree of monomer conversion and polymerization shrinkage are two of the main reasons for potential adhesion failure between the tooth structure and the restoration substrate. To evaluate the degree of conversion and polymerization shrinkage of a newly developed self-adhesive resin cement, the degree of conversion (DC) was measured using FTIR under different activation modes, temperatures, and times. Volumetric shrinkage was tested using the AcuVol video imaging method. The experimental cement showed a higher DC than other cements under self-curing. The DC of the experimental cement was higher than that of other cements, except SpeedCem Plus under light curing. The experimental cement had a higher DC than other cements, except SpeedCem Plus in some conditions under dual curing. All self-adhesive cements had a higher DC at 37 °C than at 23 °C under self-curing, and there was no statistical difference between 23 °C and 37 °C under light curing. All self-adhesive cements showed a significantly higher DC at 10 min than at 5 min under self-curing. There was no statistical difference between 5 min and 10 min for most cements under dual curing. All self-adhesive cements statistically had the same volumetric shrinkage under light curing and self-curing. The newly developed self-adhesive resin cement exhibited a higher degree of conversion and similar volumetric shrinkage compared to these commercial self-adhesive resin cements.

Keywords: degree of conversion; self-adhesive resin cements; shrinkage.

Figure 1

Degree of conversion of self-adhesive resin cements for self-curing (5 min and 10 min at 23 °C and 37 °C). (Value bars with the same letter are statistically equivalent between the tested groups).

Figure 2

Degree of conversion of self-adhesive resin cements for light curing (20 s at 23 °C and 37 °C). (Value bars with the same letter are statistically equivalent between the tested groups).

Figure 3

Degree of conversion of self-adhesive resin cements for dual curing (self-curing for 10 min plus light curing for 20 s at 23 °C and 37 °C). (Value bars with the same letter are statistically equivalent between the tested groups).

Figure 4

Degree of conversion of self-adhesive resin cements for dual curing (light curing for 20 s plus self-curing for 5 min and 10 min at 23 °C and 37 °C). (Value bars with the same letter are statistically equivalent between the tested groups).

Figure 5

Correlation of degree of conversion and flexural strength.

Figure 6

Correlation of degree of conversion and flexural modulus.

Figure 7

Correlation of degree of conversion and water solubility.

Figure 8

Volumetric shrinkage for light curing at 5 min and self-curing at 5 min and 60 min. (Value bars with the same letter are statistically equivalent between the tested groups).

Figure 9

Volumetric shrinkage of self-adhesive resin cements over time for light curing.

Figure 10

Volumetric shrinkage of self-adhesive resin cements over time for self-curing.