Composition of breast forms

The composition of breast implants

A silicone breast implant (or breast prosthesis) is a class III medical device, i.e. intended for permanent implantation in the human body. It must be CE-marked and, to be used in France, must be registered on the LPPR register of the French National Agency for the Safety of Medicines and Health Products (ANSM). It must be subject to traceability and materiovigilance.
The principle of a breast prosthesis is the same whatever the type of implant. It consists of an envelope of 3 layers of medical silicone, whose characteristics may vary, filled with silicone gel, water or Hydrogel.

The different types of breast implants

Breast implants are classified according to their filler, the characteristics of their shell and their shape.

The different types of filler.

Saline-filled breast forms
These extremely safe breast forms were used exclusively in France from 1997 to 2001. Today, they account for less than 5% of all implantations in France. Their shape is necessarily round, and their envelope necessarily smooth. Saline is injected through a filling valve during the procedure. This allows the empty breast form to be inserted through a scar of less than 2 cm. Its main advantages are the innocuousness of its filler and the fact that any wear and tear of the prosthesis will be immediately diagnosed (appearance of folds or total deflation of the implant). However, they do have certain disadvantages:

  • impossibility of having an anatomical shape
  • slightly less natural feel than silicone gel
  • possibility of abrupt deflation, possibly on vacation, with no possibility of changing the implant
  • shorter average lifespan due to implant fragility at the filling valve

Hydrogel-filled breast forms
Hydrogel is a filler composed of 95% water and 5% cellulose, which polymerizes the water into a gel. This product is totally harmless in the event of rupture, making it similar to physiological saline. Arion is the only laboratory to offer this type of gel filler. One of its problems is the possibility of a sudden increase in breast volume in the event of rupture, as the cellulose absorbs water from the patient's body.

Silicone gel-filled breast forms

Composition of breast forms

These are the most widely used breast implants in the world. Their shell is made up of 3 layers of silicone elastomer. To achieve this, a mold of a specific shape is dipped several times in specific silicones.

Composition of breast forms

An anti-perspiration barrier layer is inserted between the 2 outer and inner layers.

Composition of breast forms

Once the envelope has been manufactured, a number of checks are carried out, in particular to ensure that the thickness of the envelope is uniform.

Composition of breast forms

The hole left by the mold mandrel is occluded by a patch.

Composition of breast forms

The silicone gel is then injected into the envelope in liquid form.

The injected medical silicone is supplied by one of 2 FDA-approved gel manufacturers, Nusil or Applied Silicon. At the end of the filling process, a catalyst is added. The breast implant is then heated to polymerize the gel. We have a clear preference for Applied Silicon's responsive gel. It provides a shape-memory effect and prevents wrinkling at the top of the implant. It also has a very high resistance to stretching, which prevents the gel from fracturing when the implant is inserted.

It is a gel, not liquid silicone, that fills the prosthesis. If there is a rupture in the envelope, the gel will not spread into the body and will remain cohesive.

This complex and sophisticated design explains the advantages and disadvantages of pre-filled silicone gel breast implants. The advantages include

  • the ability to use anatomical shapes
  • a more natural, wrinkle-free feel
  • longer service life than serum-filled implants thanks to the absence of a filling valve

The disadvantages include

  • the need for a longer scar (between 3 and 6 cm depending on implant volume)
  • more difficult to monitor the integrity of the implant membrane: the implant does not deflate, and a rupture may go unnoticed on clinical examination.
  • the possibility of silicone migration in the event of unnoticed rupture

Over 95% of our breast implant cases are performed with silicone gel-filled implants. Their average lifespan is longer, but we recommend an annual clinical examination and MRI every 2 years from the 5th post-operative year onwards, to detect asymptomatic ruptures.

The different types of breast implant envelope texturing

The breast implant shell is the interface between the implant and your body. Depending on the type of envelope, your body will react differently to the implant. This is a key factor in the development of capsular contracture.

There are two types of hulls:

  • early shells (within 6 months of surgery). They are linked to the proliferation of bacteria colonizing the skin and/or mammary gland around the prosthesis (known as Biofilm). These bacteria proliferate if they have entered in large quantities, there is an accumulation of blood around the prosthesis, and the inflammatory reaction around the implant is weak.
  • late shells (between 5 and 25 years after the operation), which are linked to wear of the silicone envelope and/or implant rupture. The degraded silicone will cause local inflammation, hardening the breast and resulting in a shell.

With smooth envelopes

Smooth breast forms were the first to be marketed. Saline-filled implants are only available with this type of envelope. Smooth breast implants are only available in round shapes. Their advantages include:

  • the possibility of inserting them through a small incision
  • a thin envelope that's hard to feel
  • very little post-operative reaction around the implant

Their main disadvantage is explained by this last point. As the post-operative inflammatory reaction is very limited, the white blood cells do not eliminate the biofilm around the prosthesis, resulting in an early shell rate of almost 10%. This is particularly frequent in the case of scarring around the areola, which requires the mammary gland to be cut in two, freeing the biofilm from the galactophore ducts (bringing milk to the nipple) of the mammary gland. We do not use this type of breast implant, unless the patient desires saline-filled implants. In this case, we make a 2 cm incision under the breast.

With micro or macro-textured envelopes.

These envelopes were developed in the 1980s to reduce the shell rate. Texturing will provoke a post-operative inflammatory reaction and disorganize collagen fibers. Their main advantage is therefore the reduction in the shell rate from 10% with smooth implants to around 3% with textured implants. However, texturing does not ensure complete adhesion of the implant to the capsule. We therefore do not recommend the use of textured anatomical implants. The risk of rotation is estimated at 5% at 10 years.
Another disadvantage is that the membrane of textured implants is thicker and can be felt on palpation. We regularly use micro-textured round implants, as they reduce the risk of shell formation and can be placed through a 3 to 4 cm incision, thanks in particular to the use of the Keller Funnel.

With polyurethane foam envelopes.

The use of this coating has revolutionized breast augmentation. The polyurethane foam acts as a 3D matrix in which the cells responsible for shell formation, the fibroblasts, encapsulate themselves, thus disrupting the collagen fibers. As a result, the shell rate for a first aesthetic breast augmentation with these implants is less than 5%. What's more, the fibroblasts literally integrate the foam, imprisoning the implant (a process similar to the osseointegration of titanium dental implants). This explains why NO anatomical implant covered with polyurethane foam has ever been described. The disadvantages of these implants are their price (2 times more expensive than a conventional implant), the thickness of their wall, which is often palpable, particularly at their lower edge, and the difficulty of fitting them. Indeed, an incision of at least 5 cm is often required, and positioning is very difficult (the implants cling to the tissue).

Composition of breast forms

Breast implants have an envelope that is defined by specific molds. It defines the general shape of the implant (round or anatomical), their projection and therefore their volume.
We use these implants in over 60% of our breast augmentation cases.

The different shapes of breast implants

The rounds

These breast implants are the most widely used in the world. Their main advantage is that their shape does not change, even when the implant is rotated. However, high-profile round implants with a flat base can rotate anteroposteriorly. Round implants generally give a lot of projection in the upper part of the breast, which favors cleavage. The overall appearance of the augmented breast then takes on an apple shape (photo round implant) which some patients find not "natural" enough.

One of the problems with these implants is the possible visibility of their upper edge when the prosthesis is placed in front of the muscle, making it necessary to place it behind the muscle, which is more painful if the volume chosen is greater than 300 cc. We use this type of implant in 40% of our cases, particularly if the patient already has a well-shaped bust and wishes to obtain a more generous décolleté.


Anatomical breast forms have a lower portion below the areola that is more projected than the upper portion above the areola. Their overall shape mimics that of a natural breast (photo SL OPTICON). The overall appearance of the augmented breast takes on a pear shape with a very natural look. The upper edge is also less visible, enabling breast augmentation in front of the muscle, even for volumes in excess of 300 cc.

The major disadvantage of textured or microtextured anatomical breast implants is the risk of rotation in around 5% of cases. Such rotation usually requires a repeat operation, and we do not use this type of implant. This problem has been solved by anatomical breast implants covered with polyurethane foam. In 2 months, the implant is integrated by the body and can no longer rotate.
We use this type of implant in over 60% of our cases.


In the wake of the PIP scandal, patients are understandably very involved in their choice of breast implant, and make extensive enquiries, particularly on the Internet, before consulting their surgeon. It's important to trust your surgeon, who, thanks to his or her personal experience and the studies published in scientific journals, can offer you the safest and most appropriate implant for your case.

Our usual treatment plan is as follows:

If you already have a shaped breast and wish to increase your volume moderately to give you more cleavage, we recommend an implant filled with medium or high projection textured round silicone gel between 250 and 350 cc, inserted through a short 3 to 4 cm incision under the breast or in the armpit. We use Mentor Siltex Cohesive 2, Polytech Sublime Line or Silimed implants. If your breasts are out of shape, particularly with an ill-defined sulcus, we recommend a prosthesis filled with anatomical silicone gel covered with high-projection polyurethane foam between 275 and 350 cc, inserted through the areola or through a scar under the breast. We mainly use Polytech implants in these cases. We adapt this treatment plan to the patient's particular needs and wishes, particularly in terms of scarring.

Consult this page if you have any questions about the lifespan of breast implants.

Have a question? Please contact us.


The firm

Docteur Yaël Berdah and Docteur Marc-David Benjoar
Plastic surgeons in Paris France

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