Method: American Orthodontics (Radiance model, n=60), Ormco (Ice model, n=60) and 3M Unitek (Clarity model, n=60) were included. Bracket slots were imaged from the distal using an Olympus SZX16 (Olympus Corporation; Tokyo, Japan) microscope with mounted camera. Digital images were imported and all measurements were made with the Buehler Omninet 9.0 software program (Buehler, Lake Bluff, IL).
Bracket measurements were taken from gingival and occlusal sides at two points equidistant between slot base and top. Mean slot-dimension for each tooth/manufacturer combination was recorded. Six teeth per manufacturer were examined and results compared between companies using a set of 6 one-way ANOVAs. Mean of each bracket set (18 total sets) was compared to the manufacturing standard of 0.018, using a set of 18 one-way ANOVAs. Bonferroni correction adjusted for multiple comparisons.
Result: For all teeth, there were statistically significant differences in slot-dimensions between the three companies (p<.001 ). American brackets were statistically insignificant when compared to the manufacturing standard (p-values ranging between .026 and .441). The majority of Ormco and 3M Unitek brackets were statistically significant when compared to the manufacturing standard (all p-values <.001), with the exception of the Ormco left central incisor (p=.003). Significance was indicated when p-value is <.0028 after application of Bonferroni correction.
Company |
Tooth |
N (number of samples) |
Min. |
Max. |
Mean |
Standard Dev. |
P-value |
American |
Right Cuspid |
10 |
.0173 |
.0181 |
0.0177 |
0.00031 |
.026 |
|
Right Lateral |
10 |
.0175 |
.0189 |
0.0179 |
0.00043 |
.441 |
|
Right Central |
10 |
.0175 |
.0183 |
0.0178 |
0.00027 |
.046 |
|
Left Central |
10 |
.0176 |
.0183 |
0.0179 |
0.00021 |
.264 |
|
Left Lateral |
10 |
.0172 |
.0184 |
0.0177 |
0.00041 |
.036 |
|
Left Cuspid |
10 |
.0172 |
.0185 |
0.0177 |
0.00043 |
.038 |
|
|
|
|
|
|
|
|
Ormco |
Right Cuspid |
10 |
.0174 |
.0177 |
0.0175 |
0.00009 |
<.001 |
|
Right Lateral |
10 |
.0170 |
.0179 |
0.0176 |
0.00025 |
.001 |
|
Right Central |
10 |
.0175 |
.0177 |
0.0176 |
0.00007 |
<.001 |
|
Left Central |
10 |
.0166 |
.0179 |
0.0175 |
0.00037 |
.003 |
|
Left Lateral |
10 |
.0170 |
.0177 |
0.0175 |
0.00019 |
<.001 |
|
Left Cuspid |
10 |
.0173 |
.0179 |
0.0177 |
0.00017 |
.001 |
|
|
|
|
|
|
|
|
3M |
Right Cuspid |
10 |
.0190 |
.0195 |
0.0193 |
0.00015 |
<.001 |
|
Right Lateral |
10 |
.0196 |
.0203 |
0.0200 |
0.00023 |
<.001 |
|
Right Central |
10 |
.0189 |
.1092 |
0.0190 |
0.00009 |
<.001 |
|
Left Central |
10 |
.0187 |
.0192 |
0.0189 |
0.00015 |
<.001 |
|
Left Lateral |
10 |
.0198 |
.021 |
0.0204 |
0.00041 |
<.001 |
|
Left Cuspid |
10 |
.0191 |
.0195 |
0.0193 |
0.00013 |
<.001 |
Conclusion: Results revealed that three, tested bracket manufacturing companies consistently manufacture brackets with undersized or oversized slot-dimensions. Slot sizes varied from 0.0166 (7.78%) undersized to 0.021 (16.67%) oversized. Variations of this magnitude directly impact fit of the wire and amount of contact surface between wire and bracket slot resulting in unintended treatment effects. Products supplied by American Orthodontics and Ormco.