Objectives: to verify the degree of conversion (DC) and the post-gel shrinkage (PS) of low shrinkage commercial restorative composites.
Methods: Six BisGMA-based composites (Durafill/Heraeus-Kulzer, Filtek Z250/3M ESPE, Heliomolar/Ivoclar Vivadent, Aelite LS Posterior/Bisco, Filtek Supreme/3M ESPE, ELS/Saremco), a urethane-based (Venus Diamond/Heraeus-Kulzer) and one based on a dimethacrylate-derivative of dimer acid (N'Durance/Septodont) were tested. DC was determined using near-IR spectroscopy (n=3). Disc-shaped specimens were made (h=0,8mm, Ø=7,0mm). FTIR spectra were recorded before, 10 minutes and 72 hours after photoactivation (18J/cm2). Post-gel volumetric shrinkage (n=5) was determined using strain gages. Data were analyzed using one-way ANOVA/Tukey test, and global significance level was 5%.
Results: Results are presented in table.
Table – Means and standard deviations for DC (10 minutes and 72 hours), post-gel shrinkage, and the initial:final DC ratio rate. In the same column, means followed by the same superscript indicate absence of statistically significant difference (p>0.05).
Composite | Degree of conversion (%) | initial:final DC ratio | Post-gel shrinkage (%) | |
10 minutes | 72 hours | |||
N Durance* | 63.0 (0.7) A | 80.6 (0.7) A | 0.78 | 0.65 (0.02) A |
Filtek Supreme | 51.8 (0.9) C | 68.7 (0.8) C | 0.75 | 0.64 (0.07) A |
Filtek Z250 | 54.8 (1.9) B | 75.4 (1.8) B | 0.73 | 0.52 (0.04) B |
Aelite LS Posterior* | 62.8 (0.7) A | 75.7 (2.2) B | 0.83 | 0.52 (0.04) BC |
Durafill | 44.9 (0.4) D | 64.8 (0.6) D | 0.69 | 0.43 (0.03) CD |
Heliomolar | 45.7 (0.4) D | 65.4 (2.2) CD | 0.70 | 0.43 (0.02) DE |
Venus Diamond* | 55.7 (1.0) B | 76.1 (0.6) B | 0.73 | 0.39 (0.03) DE |
ELS* | 53.2 (0.3) BC | 68.9 (0.5) C | 0.77 | 0.35 (0.02) E |
* considered by the manufactures as low-shrinkage composites
Conclusions: It was possible to conclude that some of the approaches utilized by different manufacturers were able to successfully reduce composite post-gel shrinkage, without compromising the degree of conversion.