Objective: To compare the Shear Bond Srength (SBS) of resin-bonded metal/enamel bonds with the Fatigue-Limit and Fatigue-Life of identical joints. Methods: 285 discs of Ni/Cr-alloy1 (dia 5mm×4mm) were cast and treated by either (1)Sandblasting with aluminium oxide or (2)Sandblast + 15 min electrolytic-etch in HCl. The discs were bonded to etched enamel (37% HPO4/30 sec) using 3 bonding systems.2-4 Ten discs of each group were subjected to Shear test in a Universal Testing Machine5 (CHS= 50mm/min). Fifteen discs of each group were subjected to a Staircase Fatigue-Test using 5000 cycles, load increment = 4 kg. 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 statistic to determine the β and α coefficients for the 3 loads. Results:
|
Treatment |
Bonding system |
Shear strength |
Fatigue Limit |
|
Sandblast |
Calibra |
70 |
30 |
|
|
Panavia |
70 |
24 |
|
|
Nexus |
96 |
32 |
|
SB+Etch 15min |
Calibra |
56 |
30 |
|
|
Panavia |
42 |
22 |
|
|
Nexus |
58 |
32 |
Values in Kg. Pearson's correlation coefficient r = 0.49, p = 0.18
|
Fatigue Life |
||||||||||
|
Treatment |
Bonding systems |
Cycles (20Kg) |
β |
α |
Cycles (10Kg) |
β |
α |
Cycles (5Kg) |
β |
α |
|
Sandblast |
Calibra |
476075 |
0.4 |
432954 |
436972 |
1.2 |
498800 |
>5 M |
>50 |
>5 M |
|
|
Panavia |
3243 |
0.7 |
5038 |
33466 |
2.0 |
44971 |
>5 M |
>50 |
>5 M |
|
|
Nexus |
27690 |
0.5 |
17719 |
56751 |
2.2 |
65278 |
0.71 M |
12.8 |
0.74 M |
|
SB+Etch |
Calibra |
98132 |
0.5 |
77456 |
259281 |
0.7 |
269046 |
>5 M |
>50 |
>5 M |
|
|
Panavia |
2523 |
0.4 |
4061 |
11676 |
0.7 |
17216 |
>5 M |
>50 |
>5 M |
|
|
Nexus |
5682 |
1.2 |
6664 |
104584 |
0.9 |
128467 |
>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 UGIREXIII, UGin dentaire, France, 2 Calibra with Prime & Bond Resin, Dentsply, UK, 3 Panavia with Clearfil SE Bond, Kuraray, Japan, 4 Nexus with Optibond Solo Plus Resin, Kerr, USA, 5 Nene Instruments Ltd, UK.