38 year old, 130lbs, 5'6", augmentation 8 months ago & dent next to sternum? (Photos)

Pre-operative photos would aid in accurate answers.
It appears the depression may be from where your pectoralis muscle (chest muscle) inserts into the rib (a normal anatomical variant)
A revision may be able to release the band or it may not be fixable without a fat transfer to the depression.
Best wishes
Dr. Taranow

Dear Jac,
Breast augmentation although considered a "routine" operation these days with nearly 400,000 being performed in the US annually, is still surgery. Every surgery, no matter how routine, has risks and complications associated with it. Some of the risks are well known, more common and are discussed before surgery. Some of the risks are highly uncommon and unpredictable, not falling under the category of pre-operative discussion. It appears that your "dent" may be a disinsertion of your pectoral muscle exposing your ribs/sternum, assuming your implants are under the muscle. Sometimes minor chest wall deformities, like "dents" are present before surgery and become more visible after. An examination and review of your pre-operative photos coupled with the knowledge of the actual intraoperative events of your surgery will help your surgeon determine which factors are in play here. As outside observers without that critical knowledge, we do not have the information to give a definitive answer. See your surgeon. Good luck!