Each round silicone gel-filled breast implant is comprised of a silicone elastomer shell which contains the silicone gel filling.

Silicone gel breast implants are filled by the manufacturer with a moderately cohesive (responsive) silicone gel. If you look carefully at different implant styles, you will notice that they have slightly different shapes. The differing shapes are related to a difference in the actual three dimensional shape of the implant shell, as well as a difference in the amount of gel that fills the implant. Breast implants that have a higher fill ratio (are filled more) have a round dome-shaped top, while those that have a lower fill ratio (are less filled) show some collapse (seen as a slight indentation) in the top of the implant.

It is important to note that the stated volume of a silicone gel implant is not quite the same as the volume of the shell that contains the gel filling. The shell volume is actually slightly larger than the volume of the gel that fills it. This prevents the implant from having a firm consistency and allows for some pliability in the implant shell. It is for this reason that we can talk about “gel-to-shell volume ratio”.

You can see the differences in the examples of the gel-to-shell fill volume ratio in the examples below. Since this comparison is done with two different style implants there are some slight differences in the actual shape of the implant shell. The consistency of the silicone gel filling is identical, however. Focus on the shape of the implant dome to see the difference a higher gel-to-shell fill volume ratio makes.

15-339-v-SRM-330-Silicone-Gel-to-Shell-Fill-Volume

15-339 Moderate-Plus Profile (left) and Inspira SRM-330 (right)

Natrelle Classic Moderate-Plus Profile Implant
The 15-339 moderate-plus profile implant is filled with 339 mL of silicone gel. This implant has gel-to-shell fill ratio of about 84%. That means that the total volume the shell can accommodate is 403 mL. Since the implant is only filled with 84% of the total volume that it can accommodate,  the dome of the implant is not full and rounded, but instead is somewhat collapsed and indented.

Natrelle Inspira SRM
The Inspira SRM-330  is filled with 330 mL of silicone gel. This implant has a gel-to-shell fill ratio of 95%. That means that the total volume the shell can accommodate is 347 mL. Since the implant is filled to 95% of it’s capacity, the dome of the implant is full and round.


 

20-325-v-SRF-325-Silicone-Gel-Fill-Volume

20-325 High Profile (left) and Inspira SRF-325 (right)

Natrelle Classic High Profile Implant
The 20-325 high profile implant is filled with 325 mL of silicone gel. This implant has gel-to-shell fill ratio of approximately 84%. That means that the total volume the shell can accommodate is 387 mL. Since the implant is only filled with 84% of the total volume that it can accommodate,  the dome of the implant is not full and rounded, but instead is somewhat collapsed and indented.

Natrelle Inspira SRF
The Inspira SRF-325  is filled with 325 mL of silicone gel. This implant has a gel-to-shell fill ratio of 95%. That means that the total volume the shell can accommodate is 342 mL. Since the implant is filled to 95% of it’s capacity,  the dome of the implant is full and round.

Round breast implants that have a higher gel-to-shell fill volume ratio may exhibit less rippling, and a bit more upper pole fullness or projection than their less-filled counterparts. Speak with your surgeon to understand whether fill volume may make a difference for your augmentation.