I have 350cc saline and I am going to redo my breast. What would be the equivalent in silicone? How many cc should I get?

Thanks for your question! The cc (cubic centimeter) is a measure of volume, & doesn't really matter what substance fills that volume, whether it's saline or silicone. So 350cc silicone should be the same as 350cc saline. However, there are differences in the type of implant (high vs moderate profile for example) & placement of the implant (over vs under your chest muscle). Discuss these differences with your surgeon. Best of luck to you moving forward! 

Thank you for the question.  You are correct in that the revisionary breast surgery may involve the use of a different volume of silicone gel breast implants. However, there is no reliable/specific "conversion" factor when it comes to exchanging saline  to silicone gel breast implants. In other words, you will find that online consultants will not be able to provide you with specific advice in regards to selection of specific breast implant size/profile. 
Ultimately, careful selection of plastic surgeon and careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical. 
Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery (regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals. 
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "C or D cup” etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery ( after the use of temporary intraoperative sizers). Viewing the patient's chest wall in the upright and supine positions, with temporary sizes in place, help select the best breast implant size/profile for the specific patient.
I hope this, and the attached link (dedicated to revisionary breast augmentation surgery concerns), helps. Best wishes.

Dear Gia2007,Although 1cc of saline should equal 1cc of silicone gel because they are simply volumetric measurements, anyone that has done breast augmentation for many years and has exchanged many breast implants knows that there is usually a need for slightly larger gel implants to maintain the same breast size.  This is likely a function of the different viscosities of the materials, the form stability of the implants and the amount of saline fill that is placed in the saline implant.  With newer generation form stable silicone gel implants this phenomenon may become less of a concern.  There is no precise equivalency and your plastic surgeon would have to know the type and amount of fill in your current saline implants to determine the equivalent for your case.  Good luck!