OBJECTIVE: To investigate the correlation of rate of curing of composites with their Barcol hardness as a measure of the Energy Optimization of Polymerization (EOP). METHODS: Kinetic volumetric shrinkage was measured at 25oC using the Acuvol™ with an RG610 red filter. Barcol hardness was measured on the top and bottom (BHB) of the specimen with a 934 impresser using a 2mm thick sample cured at 500mw/cm2 for 10-40sec. RESULTS: Detailed kinetic studies for the composites determined the rate of shrinkage on curing at 500mw/cm2 for 20sec. The kinetic data were fit with a nonlinear regression equation yielding a kinetic constant (k). Barcol hardness (BHB) was plotted as a function of irradiation time and the time to achieve 90% maximum was determined using regression analysis with a reciprocal model. Correlation between the kinetic constant and the Barcol hardness was determined using ANOVA followed by simple regression analysis.
|
Composite |
Renew Op |
Renew Tr |
Z100 |
Heliomolar |
Glacier |
|
BHB @ 40sec (n=9) |
41±2 |
70±2 |
83±2 |
60±2 |
46±3 |
|
k (min-1) (n=4) |
4.9±4.4 |
12.2±2.8 |
18.8±4.8 |
6.7±3.2 |
7.1±1.1 |
|
Composite |
Pyramid En |
Pyramid Den |
Aelite LS |
Z250 |
|
BHB @ 40sec (n=9) |
74±3 |
73±1 |
66±3 |
86±1 |
|
k (min-1) (n=4) |
20.4±3.8 |
10.8±2.5 |
8.8±3.0 |
19.6±11.5 |
|
Composite |
Estelite |
Intens |
Micronew A2 |
Micronew A3.5 |
|
BHB @ 40sec (n=9) |
81±2 |
68±2 |
70±2 |
66±2 |
|
k (min-1) (n=4) |
9.0±3.5 |
11.4±8.4 |
10.6±2.1 |
11.3±1.5 |
CONCLUSIONS: The ANOVA shows that there is statistically significant relationship between the kinetic constant and the Barcol hardness (BHB) with a 99% confidence level. A linear model explains 65% of the variation.