I just glanced at the site, and they are making some pretty broad claims. I don't want to get into attacking every claim they made, but anytime a product is being sold there's a tendency to fudge the truth.
If you have dry mouth (usually a side effect of medication), there's a mouthwash called Biotene widely available in the US. It works pretty well. They also make a breath spray you can carry with you. Your dentist or doctor can diagnose thrush (candida infection). Sjogren's Syndrome is pretty rare.
Dry mouth can definately cause angular chelitis. It probably doesn't help EC but I wouldn't name it as the cause of mine.