Concerned about indentations at tops of central incisors! About to get crown lengthening surgery - 1 crown, 3 veneers. (photos)

31 yr old female. Trauma to central incisors at age 7, plus chips in both teeth covered by bonding (bonding is very old), root canal in tooth #8 at age 18, x-ray shows calcification of tooth #9. I had braces as a teen and still have to wear a retainer sometimes at night or my teeth will shift, but the retainer doesn't reach the height of the indentations. I think the indentations started within the last couple years. What could be causing them? About to get CL surgery, crown on 8, 3 veneers

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