Thank you for your question. In general, we surgeons strive to achieve natural looking breasts with a defined crease, but it always depends on the patient’s breast anatomy, the pocket of placement, the incision that was used, the amount of release made to the inframammary fold (breast fold). For your information, the inframammary fold serves a suspensory role as it prevents the breast tissue from dropping below the chest wall. To elaborate, some patients may not have defined breast shape or a defined breast fold, in which case an augmentation will increase the breast size, but not create a crease. This could be the case in patients with minimal breast tissue. The pocket in which the implant is placed (i.e., behind the muscle or above the muscle) can also have an influence. An above the muscle placement can make the breast seem fuller in the upper-pole as it allows the implant to apply direct pressure to the breast tissue (resulting in the round – 50:50 upper-pole to lower-pole ratio. It can also provide a better cleavage. On the other hand, a behind the muscle placement can provide a more natural-look with a downward slope in the upper-pole and a curvature in the lower-pole. However, early in the recovery period (i.e., before reaching the 6 month postoperative period), the implants may ride high as the breast takes to time to adapt to the implants. Over time, the effects of gravity and stretching of the skin allow tissue expansion of the breasts and the implants drop to provide the natural 45: 55 upper to lower-pole ratio. Finally, the incision used can have a great influence on the definition of the breast fold/crease. If the surgeon uses the inframammary incision which is placed directly at the site of the natural breast fold, then breasts will have a defined crease. However, if the incision is made at the transaxillary fold (through the armpit), it becomes harder to manipulate and work with the inframammary fold due to less visibility at the lower end of the pocket. This can be overcome by use of an endoscopic imaging tool which helps in guiding the dissection. As such, patients undergoing transaxillary breast augmentation are recommended to have a natural breast shape as it only works to augment the breast. Conversely, the inframammary breast augmentation cannot only help increase the size of the breasts, but also help shape the breasts. So the images you have seen may from the results of either above the muscle implant placement, or due to the transaxillary (armpit) incision. Please consult a board-certified plastic surgeon for more information. Hope this answers your question.