Objectives: To evaluate the relationship between shear bond strength (SBS) to enamel and mechanical properties of orthodontic adhesives.
Methods: Ninety freshly
extracted human molars stored initially in 0.5% Chloramine
T were randomly divided into six groups of 15
each.Brackets were bonded to teeth using: Right-On: (paste-liquid contact adhesive, TP
Sixty discs (~ 0.26 mm thick and 10 mm dia) were prepared from each material and stored in distilled water at 37º C for 24 h, for determining the following mechanical properties: shear punch strength, Nomoto et al 2001 (SPS), flexural strength, Biaxial test (FS), and (VH) Vickers hardness test.
Results: The table below shows the values (mean± sd) of SBS and the mechanical properties tested. Super-Bond was significantly the strongest material in both SBS and FS (p<0.05, ANOVA and Tukey test). For SPS and VH, Concise and Transbond were significantly greater than the rest of the materials.
|
Test(U) |
Concise |
Transbond |
Right-On |
|
Ideal |
Super-Bond |
|
SBS(MPa) |
8.02±5.76 |
5.66±1.88 |
4.45±1.31 |
6.79±3.04 |
6.33±2.4 |
20.64±3.7 |
|
SPS(MPa) |
58± 9.2 |
56. ± 8.3 |
35.6± 3.8 |
42.5± 10.8 |
33.5±7.4 |
47.9±5.1 |
|
FS(MPa) |
99± 8.8 |
108.1±9.5 |
83.8±25.8 |
30± 6.4 |
30.4±15 |
163.3±56.8 |
|
VH(VHN) |
70.7± 6.6 |
65.2± 8.8 |
20.5± 5.3 |
41.5± 5.9 |
22.6±1.4 |
9.44±1.15 |
Conclusions: There was a positive significant relation between SBS and flexural strength (P<0.05, r²=75.4%). The material with significantly greater SBS has a value of FS which was 50-500% greater than that for the other adhesives. Biaxial flexural strength test maybe used to indicate SBS. However, the relationship between SBS and other mechanical properties is complex.