Objective: To compare the Shear Bond Srength (SBS) of resin-bonded ceramic /enamel bonds with the Fatigue-Limit and Fatigue-Life of identical joints. Methods: Methods: 105 discs of ceramic1 (dia 5mm×4mm) were sintered, sandblasted and etched for 15 min with HF2. The discs were bonded to etched enamel (37% HPO4 for 30 sec) using three bonding systems3-5. Ten discs of each group were subjected to Shear Test in a Universal Testing Machine6 with a cross-head speed of 50mm/min. Fifteen discs of each group were subjected to a Staircase-Fatigue-Test using 5000 cycles(1.33 Hz), load/deloading increment = 4 kg. Specimens that survived were stained with AgNO3. Another 10 discs were subjected to cyclic loads of 20, 10, and 5 kg to determine Fatigue Life of the bonds. Load data was compared by correlation analysis and cycle data by Weibull analysis to determine the β&α coefficient for the 3 loads. Fracture surfaced were examined by incident light microscopy and SEM. Results:
|
Treatment |
Bonding system |
Shear strength |
Fatigue Limit |
|
Sandblast + Etch |
Calibra |
42 |
28 |
|
|
Panavia |
32 |
24 |
|
|
Nexus |
36 |
23 |
Values in Kg. Pearson correlation coefficient r = 0.49, p = 0.18
|
Fatigue Life |
||||||||||
|
|
|
Cycles (20Kg) |
β |
α |
Cycles (10Kg) |
β |
α |
Cycles (5Kg) |
β |
α |
|
SB+Etch |
C |
5031 |
1.5 |
5422 |
168156 |
0.9 |
212662 |
>1 M |
>50 |
>1 M |
|
|
P |
7028 |
0.5 |
7631 |
114428 |
0.5 |
109217 |
>1 M |
>50 |
>1 M |
|
|
N |
7373 |
1.8 |
8628 |
150313 |
0.4 |
207697 |
>1 M |
>50 |
>1 M |
Conclusion: The Fatigue-Limit of the bonds was much lower than the Shear strength and there was no correlation between the two values. Fatigue-Limit was not a good predictor of the Fatigue-Life in this study. 1 Vitadur Alpha, Vita, Germany, 2 Porcelain Etch-it Gel, American Dental Supply, USA, 3 Calibra with Prime & Bond Resin, Dentsply, UK, 4 Panavia with Clearfil SE Bond, Kuraray, Japan, 5 Nexus with Optibond Solo Plus Resin, Kerr, USA, 6 Nene Instruments Ltd, UK.