Objectives: To evaluate the influence of BisGMA/TEGDMA (B/T) and UDMA/TEGDMA (U/T) ratios on polymerization stress (σpol) and its determinants, namely, degree of conversion (DC), volumetric shrinkage (VS) and elastic modulus (E), and to verify the relationship between σpol and the others variables.
Methods: Experimental composites were formulated with 2:8, 3:7, 4:6, 5:5, 6:4, 7:3 e 8:2 in mol% of B/T or U/T and 15wt% of silica (Aerosil R972). σpol was determined by curing the composite (h=1mm) between acrylic rods (r=3mm) attached to an universal testing machine. VS was determined in a linometer. E was obtained by three-point bending. DC was accessed by near-FTIR spectroscopy. All values were collected 15 minutes after photoactivation. Data were submitted to one-way ANOVA/Tukey test (α=0.05%) for each series separately.
Results: Data are showed in the table. For each series, composites with similar letters do not differ statistically.
Polymerization stress (MPa) | Volumetric shrinkage (%) | Elastic modulus (GPa) | Degree of conversion (%) | ||
B:T | 2:8 | 8.3±0.5a | 8.4±0.1a | 1.2±0.1a | 62.6±0.7ab |
3:7 | 8.1±0.7a | 8.1±0.6a | 1.1±0.1a | 65.6±0.3a | |
4:6 | 7.1±0.3b | 7.0±0.6b | 1.2±0.1a | 61.4±2.7b | |
5:5 | 6.3±0.1b | 6.2±0.3bc | 1.1±0.1a | 59.3±0.3bc | |
6:4 | 5.0±0.3c | 5.6±0.3cd | 0.9±0.1b | 56.9±0.7c | |
7:3 | 4.1±0.5c | 4.5±0.2de | 0.8±0.1b | 51.4±1.1d | |
8:2 | 4.1±0.4c | 3.9±0.1e | 0.5±0.1c | 44.0±0.6e | |
U:T | 2:8 | 9.3±0.5a | 10.1±0.7a | 1.2±0.1a | 62.6±0.7ab |
3:7 | 8.1±0.3b | 9.0±0.5ab | 1.2±0.1a | 65.6±0.3a | |
4:6 | 7.6±0.2bc | 8.6±0.6bc | 1.1±0.1a | 61.4±2.7b | |
5:5 | 7.5±0.2bc | 8.3±0.3bc | 1.0±0.1ab | 59.3±0.3bc | |
6:4 | 7.2±0.3c | 7.9±0.3bc | 0.9±0.1bc | 56.9±0.7c | |
7:3 | 6.4±0.2d | 7.3±0.5cd | 0.9±0.1cd | 51.4±1.1d | |
8:2 | 5.7±0.4e | 6.4±0.3d | 0.8±0.1d | 44.0±0.6e |