Figure 6.

Scanning electron microscopy images of uncoated (A), alumina (Al₂O₃)-coated (B), titanium nitride (TiN)-coated (C), and chromium nitride (CrN)-coated (D) bracket samples after brushing and thermal cycling tests. In areas where toothbrush contact is very high, such as the outer surfaces of the bracket wings, it appears that the Al₂O₃ coating (B) was not affected much by brushing and thermal cycling tests, but the TiN coating (C) was slightly affected and the CrN coating (D) was very much affected.