While hydrogen peroxide has been an effective option for treatment of stomatitis for many years, now that it is quite readily available, I personally prefer the chlorhexidine. There are benefits to both, however.
The hydrogen peroxide will help break up and facilitate removal of the caseation...but the foaming can increase the risk of ingestion or aspiration if the handler is not very careful. Some recommend against its use for mouthrot, on the basis that it also disrupts healthy tissue and can actually prolong the healing process (specifically, the tissue under/around the affected spot - not normal, unblemished mucosa)....in other words, once it goes through the white stuff, it starts on the pink stuff. Don't take that the wrong way, its not going to just keep eating its way through good tissue & turn a small sore into a gaping wound...it just, well, aggravates the injured area. (trying to think of a good description.........ok - kind of like using a scrub brush to clean a scrape on your arm every day. It works, but sometimes the scrape takes longer to heal because the brush aggravates the condition and disrupts the healing skin)
When using chlorhexidine, you sometimes have to work a little harder to clean/clear the affected area sufficiently...but it works quite nicely and is neater.
There are also varying recommendations regarding cleaning/treatment: ranging from twice/day, to every 2-3 days. Personally, I tailor it to the snake & the particular situation. If this is just a matter of irritation do to foreign particles in the mouth, it should clear up pretty quickly. If, on the other hand, it is a secondary issue, you will need to find/correct the primary problem.