Thanks for your post and your other reply. Sorry to hear you had this for such a long time. It really is a incredibly frustrating and depressing condition so I empathise.
I have literally spent months researching this in academic medical journals (luckily I have access to my university online resources medical journals, although I'm not a medical student, so I really should be doing my course work). But I felt like I needed to figure this out on my own because the Drs I saw seemed at a loss. My long term experience with other health problems also taught me to be sceptical about medical authority and misdiagnosis, to ask questions, be open to having your own hypothesis falsified, and be your own health advocate.
I think the EC has a lot to do with dry mouth (certainly for a subset of patients, if not all patients. Almost everyone on this board mentions they get a white line of build-up of dead sticky skin cells inside their mouth which is a definite symptom of dry mouth ). I think EC could be some sort of localised, autoimmune psoriatic reaction triggered in response to dehydration of the mucous membrane skin. Or it could just be simply caused by dehydration of the mucous membrane skin at the edge of the mouth secondary to dry mouth (injury from dehydration causing Koebner phenomenon).
It's probably complicated by other factors like opportunistic infection but I don't think that infection (bacterial or fungal) is the root cause.
I know that some HIV patients get Exfoliative Chelitis and it is thought to be caused by an overgrowth of candida. However, what researchers haven't really noted is that HIV patients are on strong drugs which cause dry mouth, which makes the oral mucosa, in already immunocompromised patients, succeptible to candida infection. Why does the candida target the lip skin in HIV patients specifically ?
Possibly treatment of secondary infection helps some people to get the inflammation under control and thus heal the chelitis with Aquaphor or similar emollient. I can also see a case for, people having less anxiety after their EC lesions start to clear up due to treatment with antifungals or similar(thus the cause of dry mouth is lessened in a sort of virtuous circle). Also less swelling means less exposure of the mucosa to air. That's my best, informed hypothesis anyway.
This is why we need randomised controlled studies. People claiming to be cured on the internet might not be cured for the reason they think they got cured.
People might think that the reaction is too severe to be caused by simple lack of saliva at the edge of the mouth but the fact that Stogren's patients get EC proves that EC can be caused by lack of saliva and consequent dehydration of mucous membrane tissue (complicated by opportunistic infection by candida and so on).
As you said dry mouth is multifactorial so it could be due to, various causes and aggravating factors, for example
1)systemic disease like Stogren's or Thyroid disease since "Burning mouth syndrome, a condition that causes a burning pain in the mouth, and Sjogren's syndrome, a condition that causes dry mouth, are more common in people with thyroid disease" 2)anxiety 3) a mouthbreathing habit 4) Allergies or nasal obstruction blocking nasal breathing
5) medications with dry mouth as side effects including Accutane 6) plastic surgery which effects lip angle 7) life style factors such as over-consumption of high caffeine drinks or smoking 8) structural anatomy of lips ( if you have poor "lip competence" due to malocclusion) 9) dehydration 10) sleeping at night with your mouth open 11) Some combination of the above factors as well as others not identified (most likely).
I agree that the cause of your dry mouth might mean that different treatments will work for different people, depending on the cause of your dry mouth.
Ok, so going on the hypothesis that there is something to do with EC and Dry Mouth Syndrome, I started researching various treatments for dry mouth. Currently, I'm trying out the following regimen:
1) I am using Biotene Saliva Replacement Gel on the inner rim of my mouth (it is not advertised to use it in this way, but I figured this is where I need it. It should be applied right up to the pint where your muscuos membrane ends).
2)I am using Gloves in a Bottle Lotion(thanks to CottonMouth for the recommendation). It is important to apply this before the Biotene Saliva gel because it forms an impenetrable barrier, preventing the saliva gel from getting on your dry lip skin (or crust, such as the case may be) and thus preventing irritation.
3)Using Saliva Stimulant mints.
4)Wearing an Easy Sleep Pro Chin strap ( a bit of headgear that stops your from mouthbreathingg in the night).
5) Using an air humidified in my room during the day (directed near my face).
My case is really severe but I started using this only recently and am already seeing some results.