Methods: Twenty extracted premolars were mounted in stainless steel rings, etched, and scanned with an optical 3D scanner. The first scan was the ‘baseline’. Stainless steel orthodontic brackets (3M Unitek Victory Series) were bonded onto the facial surface using Transbond XT adhesive (3M Unitek). After 8 days, the brackets were debonded (Weingart plier) and scanned (‘debond’). Remaining resin was removed with a carbide finishing-bur and the teeth were scanned again (‘cleanup’). Reference tooth areas (occlusal, lingual and buccal surfaces unaffected by the bracket) of ‘debonded’ and ‘cleanup’ scans were fit to the ‘baseline’ scans using Cumulus software. Surface changes (volume gain/loss, and height/depth) were calculated and statistically analyzed with a paired t-test.
Results: Debonding of the orthodontic brackets resulted in enamel loss or resin remnants on the enamel. Surface changes (mean±standard deviation) and p-values are shown in the table. Positive values indicate gain, negative values indicate loss. Volume change and height of resin remnants left on the enamel surface were significantly less after the cleanup. The volume of enamel loss that occurred between bracket removal and cleanup increased significantly, but the depth did not.
|
Volume Loss/Gain (mm3) |
Depth/Height (mm) |
||
|
Debonded |
Cleanup |
Debonded |
Cleanup |
Enamel |
-0.565±0.247 |
-0.791±0.205 |
-0.024±0.008 |
-0.025±0.008 |
P=0.00001 |
P=0.34755 |
|||
Resin |
0.729±0.724 |
0.022±0.051 |
0.085±0.046 |
0.020±0.029 |
P=0.00037 |
P=0.00002 |
|||
Conclusion: Enamel loss and resin remnants after bracket debonding and cleanup could be quantified using a precise 3D scanner. Cleanup with a finishing bur significantly removed resin but also removed some enamel.