Breast Aug - Silicone Vs Saline Impants?

I have three questions regarding breast augmentations: 1) How safe are the new silicone impants? Does the company who mfg them matter (ie mentor, allergan)? 2) What is the weight difference between 300 cc's saline implant vs. 300 cc's silicone other words, which weighs more? 3) Lastly, is the surgery process different for saline patients vs. silicone patients?

Doctor Answers 8

Silicone is actually lighter by a very small amount

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Hello Miss Z,


Years ago I really wanted to get to the bottom of this saline / silicone weight issue, so I contacted the actual engineers who design the Allergan implants.  Here's my question and their answer (my question was based on an example of 400cc implants).  The short answer is: the weight is so close, you don't need to worry about it.  As to the other questions, I agree with the other two doctors who have answered the questions.  You'll get a lot more information on these issues during your consultation, but that's a great start.


Ok now here's the exact text from my question and the Implant engineer's answer:



“What is the specific gravity of silicone?  Patients ask me all the time how much lighter silicone is than saline.  Could you please weigh a 400 cc silicone and 400 cc saline implant and tell me what each weighs in grams?”


Answer from Allergan breast implant engineer:

Specific gravity of silicone is approx. 0.98 grams/cc so gel is slightly less dense than saline.  However, the shell contributes to the overall weight.  With Saline implants we ship a shell that might weigh 25 grams (could be more could be less depending on size). The doctor then fills with saline to some volume and the weight of the device is the saline fill plus the shell.  In the case of a saline implant that is labeled as a 400cc breast implant, if the doctor adds 400cc the device could weight maybe 425 grams.

For silicone we fill by weight on the manufacturing floor.  Before doing so we tare the shell out.  So if the shell weighs 25 grams we zero the scale before adding silicone.  The weight of a 400cc gel is actually about 410 grams maybe.


As you can see the density of gel is so very close to saline that we consider them equal.  However, gel is ever so slightly less heavy.


So there you have it.  Good luck Miss Z!



Dr. Mosser

San Francisco Plastic Surgeon

Silicone Implants

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1) Silicone implants are very safe. The newest generation has been FDA approved and has a very robust safety profile. Both Mentor and Allergan are FDA approved manufacturers, so the company is not important.

2) The weight difference is minimal. Saline is slightly more dense than silicone, but this difference is nearly imperceptible in terms of weight-- it's the weight of a few paper clips at most.

3) The surgery process is generally the same, however incisions can be made smaller with saline implants.

Good luck with your surgery.

Lara Devgan, MD, MPH
New York Plastic Surgeon

Silicone vs. saline

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The FDA has studied silicone implants extensively and found them to be safe.  Mentor & Allergan are both leading implant manufacturers. Just recently, the FDA approved another manufacturer – Sientra. Your surgeon may have a preference; recommending one vs. the other.  A 300 saline or silicone implant should weigh about the same. Silicone and saline implant surgery is very similar, with the exception being the size of the incision. Since silicone implants are prefilled, it requires a slightly longer incision.


The differences between saline and silicone gel implants are subtle but can be signficant

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Breast augmentation using implants involves some important decisions and judgment on the part of your surgeon. 


The two types of implants available are saline (sterile salt water) and silicone, which is an inert gel. 


Saline implants can ripple slightly more than silicone (visible or palpable folds in the implant that may be seen or felt through the breast skin). 


Silicone gel implants tend to ripple less and can have a more natural look and feel.  It is for this reason that I usually recommend them for my patients, who uniformly desire a NATURAL result that does not look fake. 


Silicone is safe, and silicone gel implants are in fact the most widely-studied medical device in the history of medical devices! 


The different in specific gravity (density, or weight) between the two types of implants is not significant - however, saline is slightly more dense to 4 decimal places.  Therefore, there is no perceptible difference between two implants of the same volume when you consider the weight. 


The process to insert these types of implants is very similar.  Be sure to visit a Board-Certified Plastic Surgeon with experience in the procedure you are seeking. 


Karen M. Horton, MD, MSc, FACS, FRCSC

Plastic Surgery, Aesthetic Surgery, Reconstructive Microsurgery

Karen M. Horton, MD
San Francisco Plastic Surgeon

Saline or Silicone Breast Implants?

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The type of implant used may  determine the final outcome of breast augmentation surgery, especially if the patient does not have significant covering breast or adipose tissue. For example, some surgeons feel that silicone implants have a more natural look and feel than saline implants because silicone gel has a texture that is similar to breast tissue.

Each patient differs in the amount of breast tissue that they have.  If a patient has enough breast tissue to cover the implant, the final result will be similar when comparing saline implants versus silicone gel implants.  If a patient has very low body fat and/or very little breast tissue, the silicone gel implants may provide a more "natural" result.

On the other hand, saline implants have some advantages over silicone implants. Silicone implant ruptures are harder to detect. When saline implants rupture, they deflate and the results are seen almost immediately. When silicone implants rupture, the breast often looks and feels the same because the silicone gel may leak into surrounding areas of the breast without a visible difference.  Patients may need an MRI to diagnose a silicone gel rupture.   Saline implants are also less expensive than the silicone gel implants.

Other differences involve how the breast implants are filled. Saline implants are filled after they’re implanted, so saline implants require a smaller incision than prefilled silicone breast implants.
On May 10, 2000, the FDA granted approval of saline-filled breast implants manufactured by Mentor Corporation and McGhan Medical. To date, all other manufacturers’ saline-filled breast implants are considered investigational.
As of 2006, the FDA has approved the use of silicone gel implants manufactured by the Mentor Corporation and Allergan (formerly McGhan) for breast augmentation surgery for patients over the age of 22.

Silicone breast implants actually weigh slightly less than do saline breast implants.

I hope this helps.

Silicone vs saline implants

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The two implant companies Mentor and Allergan provide very similar implants, and the saline and silicone are very close in weight.  The surgery process is usually the same.

Saline v's Silicone

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Very good questions, silicone implants have been back in the market since 2006 and are better quality then they were years ago. Silicone does weigh more then saline, silicone is a heavier product then water (saline). The only difference between companies that make the implants are the shapes and sizes they come in, they're almost the same. The only difference in saline and silicone surgery in regard to the process is that with silicone the incision does need to be a little bigger.

Stuart B. Kincaid, MD, FACS (in memoriam)
Beverly Hills Plastic Surgeon

To use saline or silicone breast implants

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Miss Z,

Thanks for your question. I'll answer your questions separately;

1) How safe are the new silicone implants? Does the company who mfg them matter (ie mentor, allergan)? There are now 3 breast implant manufacturers who sell silicone breast implants, Allergan, Mentor and now Sientra (these are the same silicone implants that have been sold in Brazil and around the world known as Silimed. You should take comfort in the FDA approval process that based upon all available science that they have reviewed, the implants are considered safe.

2) What is the weight difference between 300 cc's saline implant vs. 300 cc's silicone other words, which weighs more? In the volume you are discussing it is a minimal difference. In larger implants we have to be cautious with saline-filled implant sizers and the actual silicone implant.

3) Lastly, is the surgery process different for saline patients vs. silicone patients? There is sometimes a need for a little larger if an incision because a silicone implant comes pre-filled but on average the incision length is 3.5 t 4.5 cm.


I hope this helps.


Dr Edwards

These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.