Hi Minniea,
There are a couple of items in the news section of the OCF that relate to this.

While I've not seen any information about a salivary gland transplant, there are studies where the glands are removed before radiation and replaced afterward, and one talks about genetically repairing salivary tissue genetically after treatment.

Here are the links:

http://www.oralcancerfoundation.org/news/story.asp?newsId=632

and
http://www.oralcancerfoundation.org/news/story.asp?newsId=57

You ask a very good question. Best, Sheldon