Effect of Tack Cure on Polymerization Shrinkage of Resin-based Luting Cements

Curing modes affects micro-tensile bond strength and durability of dual curing resin cements to dentin

Background

To evaluate the effects of curing modes on the micro-tensile bond strength and durability of 6 different dual curing resin cements to dentin.

Methods

84 human molars were divided into 7 groups (n = 12), and were further distributed into two subgroups according to the two curing modes: light-curing (L) and self-curing (D) (n = 6). The 6 dual-cured resin cements were: DU (Duolink, Bisco), TC (TheraCem, Bisco), MS (Multilink Speed, Ivoclar), N3 (Nexus 3 Universal, Kerr), R2 (RelyX U200, 3M) and RU (RelyX Ultimate, 3M). The universal adhesives were: All Bond Universal (Bisco); Adhesive Universal Vivapen (Ivoclar); Optibond Versa Adhesive (Kerr); Scotch Bond Universal Adhesive (3M). RU was placed directly on processed adhesive layer without light-curing, set as group 7. Micro-tensile bond strength test was carried out after 37°C water storage for 24 h, 3 months and 6 months, respectively. Three-way ANOVA and Games-Howell test were performed by SPSS 19.0 (α = 0.05).

Results

The Three-way ANOVA indicated that bonding performance was significantly affected by curing mode (p = 0.000, F = 1,237.510), resin cement (p = 0.000, F = 59.507) and storage time (p = 0.000, F = 97.888). The interaction of these three factors was significant (p = 0.017, F = 2.071).

Conclusion

The bonding strength and durability of dual curing resin cements were significantly improved by light-curing process. In addition, the bonding strength of resin cements with different experimental condition was material depended. Among all tested resin cements, N3 exhibits the most favorable outcomes.

Clinical Relevance

A dual curing procedure is recommended in clinical application. Among all tested resin cements, N3 exhibits the most favorable outcomes.

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

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.