Radiesse website lists the following:
Vocal fold insufficiency is a condition in which one or both vocal folds (sometimes called vocal cords) do not vibrate properly. This results in reduced voice quality, such as a breathy voice or hoarseness, abnormal voice changes; or complete loss of voice in some cases. Radiesse injection is a safe and effective treatment option for restoring the quality of your voice. When undergoing vocal fold augmentation with Radiesse, you can remain awake and able to talk – allowing your physician to immediately assess your speech, making treatment more accurate.
I had this injected into both vocal cords in order to help achieve closure - my vocal cords are bowed on top of the ST. It was my understanding from my doctor that it wasn't to "cure" or help the SD, but to "bulk" up the vocal cords in order to produce closure.
