Let me first note that is meant as a guide and not a historical thesis. However, I could not resist adding the paragraph below from Wikipedia:
From the first half of the twentieth century, physicians used other substances as breast implant fillers—ivory, glass balls, ground rubber, ox cartilage, Terylene wool, gutta-percha, Dicora, polyethylene chips, Ivalon (polyvinyl alcohol—formaldehyde polymer sponge), a polyethylene sac with Ivalon, polyether foam sponge (Etheron), polyethylene tape (Polystan) strips wound into a ball, polyester (polyurethane foam sponge) Silastic rubber, and teflon-silicone prostheses.
The first “breast filler” surgery took place in 1895, and involved fat being transferred to the breast.The main thing to note is that today, we largely have only saline and silicone implants. There has been a variety of different fill substances and coatings. but those have largely been discarded due to a variety of problems.
What has changed is that there are two basic coverings for the implants: smooth and textured (small spikes or velcro-like). Also, there now are options in the profile of the implant. This means that the base diameter gets smaller as the implant projects more forward. Over time, the options in this area have increased considerably. Although there are certainly instances where it is helpful to have a smaller base diameter and to have an implant that projects more prominently, I often feel that there are variations between each model. When it is only measured in millimeters, it is driven more by a marketing desire (so a woman can feel that she is more in control) than of any practical reasoning. In my opinion, one cannot possibly notice difference of this small amount.
The other big change is in the “cohesiveness” of the silicone implant. This means that the silicone implant gets firmer – and subsequently, more expensive. This could be beneficial for the woman with very thin skin and soft tissue so that it is less likely to show rippling. In general, the greater the cohesiveness and firmness, the more the company is charging for the implant. But again, depending on the skin condition, that may be the more desirable option, if you’re already taking the time and effort to improve your appearance in this area.
The good thing is that we now have implants that we believe to be both safe and effective, and with a variety of options, so that everyone should be able to find an implant that will be effective for them and give them their desired end result.