IADR Abstract Archives
Correlation between Initiator Concentration and Physical Properties of Self-curing Cements
Objective: The luting material was stored at 37°C and 50°C. Thereby the initiator concentrations of CHP and ATU was determined periodically as well as the flexural strength and modulus of elasticity. A hypothesis was stated that there will be a direct correlation between the concentration of the initiators and the physical properties.
Method:
The luting material was stored at 37°C and 50°C. The concentration of the initiators CHP and ATU was determined by means of HPLC-Chromatography.
Flexural strength and modulus of elasticity was measured according to ISO-4049:2009 in the self-curing mode.
ANOVA was used to determine statistical differences (p<0.05).
Result:
The HPLC investigation has been shown, that the ATU-concentration drops only slightly during storage at 37°C and 50°C, therefore these values are not included in the table. However the CHP-concentration decreases significantly during the observed period of time, which has an influence on the physical properties of the luting material.
Storage-time-(weeks) |
CHP-37°C-(%) |
CHP-50°C-(%) |
37°C-Flexural-strength-(MPa) |
37°C-Modulus-of-elasticity-(MPa) |
50°C-Flexural-strength-(MPa) |
50°C-Modulus-of-elasticity-(MPa) |
Initial |
0.90 |
0.90 |
92.8±8.9a |
3932±378a |
92.8±8.9a |
3932±378a |
8 |
0.80 |
0.64 |
96.2±7.6a |
3806±410a |
85.7±12.0a |
3335±408a |
12 |
0.81 |
0.57 |
102.7±7.5a |
4552±399a |
92.2±9.5a |
3927±493a |
16 |
0.71 |
0.43 |
102.5±10.7a |
4048±382a |
80.0±6.7a |
3131±384a |
20 |
0.70 |
0.41 |
90.6±5.8a |
3506±362a |
60.4±9.7b |
2069±463b |
24 |
0.67 |
0.38 |
94.4±10.5a |
3915±319a |
46.2±6.4b |
1240±282b |
40 |
0.60 |
0.25 |
79.9±3.9b |
3066±210b |
24.9±6.4c |
466±166c |
48 |
0.57 |
- |
87.7±9.9a,b |
3468±484a,b |
- |
- |
Conclusion: The stability of ATU is not critical. More critical is the stability of CHP. A reduction of the CHP-concentration from 0.9% to 0.5% has almost no effect on the physical properties, but values below 0.5% have a significant influence on the strength of the luting material. The hypothesis was confirmed.