A Study of the Safety and Effectiveness of the Mentor Larger Size MemoryGel Ultra High Profile Breast Implants in Subjects Who Are Undergoing Primary Breast Reconstruction or Revision Reconstruction

Inclusion Criteria: * Subject is female and is at least 18 years old * A candidate for: * Primary breast reconstruction in women at least 18 years old with surgically absent breast tissue (two-stage reconstruction \[tissue expanders utilized with or without the use of human acellular dermal matrices (ADM), limited to AlloDerm® and FlexHD® PLIABLE, utilized in a prior surgery to expand tissue for study device placement\] to replace breast tissue post-mastectomy) * Revision surgery in women at least 18 years old with surgically absent breast tissue (previous reconstruction with silicone-filled or saline-filled implants or revision reconstruction requiring expansion surgery prior to surgery for study device implantation, with or without the use of human acellular dermal matrices (ADM), limited to AlloDerm® and FlexHD® PLIABLE, utilized in a prior surgery to expand tissue for study device placement) * Subject understands and signs the Informed Consent * Subject agrees to return device to Mentor if device is explanted * Subject agrees to comply with follow-up procedures, including returning for all follow-up visits * Physician determines implant volume appropriate for the patient taking into account the subject's BMI and chest width Exclusion Criteria: * Subject is pregnant at time of enrollment * Subject is a current smoker, or has smoked within 3 months prior to enrollment, or plans to resume smoking within 3 months post-enrollment * Currently has uncontrolled diabetes (at time of screening or enrollment) * Has nursed a child within 3 months of study enrollment * Confirmed or suspected diagnosis of the following rheumatological autoimmune diseases or immune compromised status: SLE, Sjogren's syndrome, scleroderma, polymyositis, or any connective tissue disorder, rheumatoid arthritis, crystalline arthritis, infectious arthritis, spondyloarthropathies, any other inflammatory arthritis, fibromyalgia, or chronic fatigue syndrome * Currently has a condition that could compromise or complicate wound healing. Note, obesity alone is not an exclusion. All surgical risk factors (obesity, diabetes, smoking history, and prior radiation) should be considered in totality for proper subject selection * Infection or abscess anywhere in the body * Demonstrates tissue characteristics that are clinically incompatible with successful use of a breast implant (e.g. inadequate tissue or compromised vascularity) * Possesses any condition, or is under treatment for any condition which, in the opinion of the investigator and/or consulting physicians(s), may constitute an unwarranted surgical risk * Anatomic or physiologic abnormality that could lead to significant postoperative adverse events * Demonstrates characteristics that are unrealistic/unreasonable with the risks involved with the surgical procedure * Untreated active, or inappropriately/inadequately treated breast malignancy, without surgical treatment * Anticipated need for use of ADM/mesh at the time of implant or implant exchange * Subject is HIV positive * Works for Mentor or the study doctor or is directly related to anyone who works for Mentor or the study doctor * Implanted metal or metal devices that make a MRI scan prohibitive, history of claustrophobia or other condition that would make a MRI scan prohibitive