Physical properties of silicone gel breast implants. Are the different brands different? Does it matter? Journal time!

This is out of the Aesthetic Surgery Journal March 2019.  “Physical Properties of Silicone Gel Breast Implants.” Yawn.  Not a catchy title, but important things to know.  With the options for silicone gel implants exploding, how do you choose?

There are some things which are not addressed here:

• the width and projection of the implant, which give you the profile of implant (low, medium, high profile)
• the volume of the implant (measured in ccs, which ranges from 120-600)

The study:

• They looked at 4 manufacturers: Sientra, Mentor, Allergan, and Establishment labs
• They did bench testing to look at
  • form stability– does the device retain its dimensions when you move from horizontal (lying down) to vertical (standing up)?  The less it changes, the more they have shape retention.
  • dynamic response to the gel– when you compress it, what is the gel cohesivity, resistance to gel deformation (stiffness), and energy absorption (softness)?
  • Shell thickness, tested in five regions of the implant.
• They tested 3 textured shaped implants, 6 textured round implants, and 8 smooth round implants.  They tested 6 of each type.

Findings:

• Form stability:
  • SHAPED SILICONE GEL BREAST IMPLANTS: Natrelle 410 implants containing Truform 3 gel retained significantly more of their original dimensions than Mentor MemoryShape and Sientra Textured Shaped implants.
  • TEXTURED ROUND SILICONE GEL IMPLANTS: Inspira (Allergan) implants with Truform 3 gel, followed by TruForm 2 gel.
    • Sientra had the lowest form stability in height,
    • Mentor had the lowest form stability in projection
    • Inspira Truform 1 gel had lower form stability in the upper pole.
  • SMOOTH ROUND SILICONE GEL IMPLANTS: Inspira Truform 3 gel was equal to Motiva ProgressiveGel Plus
    • Inspira Truform 2 gel was equal to Motiva ProgressiveGEl Ultima
    • Sientra implants with High Strength Cohesive Plus gel did in the middle
    • Mentor implants Cohesive 1 implants had lowest form stability in each dimension
• Gel Material Properties
  • Allergan Natrelle 410 implants with TruForm 3 had significantly higher gel cohesion, resistance to gel deformation, and lower energy absorption complared to Mentor MemoryShape or Sientra Textured shaped implants
    • Truform 3 had higher retention of all 3 properties than Truform2 or Truform 1
  • In general the gel properties of the implants varied “significantly across devices.” The order of gel cohesion:
    • Natrelle 410 or round with TruForm 3 gel
    • Mentor textured shaped with Cohesive III gel
    • Sientral with High Strength Cohesive gel
    • Motiva with ProgressiveGel Ultima
    • Mentor with Cohesive 1 gel
    • Inspira with TruForm 1 gel
• Shell thickness
  • Allergan shell thickness was consistent in all textured implants regardless of shape
  • Natrelle 410 and Mentor MemoryShape had the same mean shell thickness.
  • Sientra textured were thinner
  • The round textured implants, Inspira implants were thicker than Mentor implants or Sientra implants

So what does this all mean??

In their discussion, the authors talk about these differences may affect performance of the breast implants in clinical settings.  If you have more form stability, you will retain the breast implant shape better.  The more cohesive the gel in the breast implant means more form stability, which determines shape retention.  The shell thickness may also have an effect.

What does this mean to you?

After reading this, or skimming this, or just skipping all of the above and reading my summary here, you may think- aha! I need to do a form stable implant with the highest cohesive gel so my implant retains its shape as much and as long as possible.

Not so fast.

The more cohesive the implant, the firmer the breast feels. I have patients who think their implant has a capsular contracture because the implant feels firm.  They don’t have capsular contracture. They are just feeing the firmness of the high cohesive silicone gel itself.

The higher cohesive gels also keep the upper pole of the breast fuller, which for those who want a more cleavage, augmented look is great.  But for those who want a more subtle, natural look having a really full upper pole looks like they had a breast augmentation- and they don’t want that.

All of the brands have variations in cohesiveness- hence the confusing lingo above with different levels of cohesive gel. It seems that Allergan TruForm 3 gel is the most stable.  (Of note, this study was done by Allergan consultant doctors, and in the critique of the study, it was noted an independent study supporting these findings would be nice.)

When you meet with your doctor, ask to feel the different cohesive gels.  They should have samples of each.  I think it is useful for you to feel it- you will know which you like the best. I use primarily Allergan implants.  I can have you feel and squeeze an implant with TruForm 1, 2, or 3 type gel.