<Li> Or a combination of the above organisms, (a polymicrobial infection) with about 60% of cases involving both C. albicans and S. aureus . </Li> <P> Candida can be detected in 93% of angular cheilitis lesions . This organism is found in the mouths of about 40% of healthy individuals, and it is considered by some to be normal commensal component of the oral microbiota . However, Candida shows dimorphism, namely a yeast form which is thought to be relatively harmless and a pathogenic hyphal form which is associated with invasion of host tissues . Potassium hydroxide preparation is recommended by some to help distinguish between the harmless and the pathogenic forms, and thereby highlight which cases of angular cheilitis are truly caused by Candida . The mouth may act as a reservoir of Candida that reinfects the sores at the corners of the mouth and prevents the sores from healing . </P> <P> A lesion caused by recurrence of a latent herpes simplex infection can occur in the corner of the mouth . This is herpes labialis (a cold sore), and is sometimes termed "angular herpes simplex". A cold sore at the corner of the mouth behaves similarly to elsewhere on the lips, and follows a pattern of vesicle (blister) formation followed by rupture leaving a crusted sore which resolves in about 7--10 days, and recurs in the same spot periodically, especially during periods of stress . Rather than utilizing antifungal creams, angular herpes simplex is treated in the same way as a cold sore, with topical antiviral drugs such as aciclovir . </P> <P> 22% of cases of angular cheilitis are due to irritants . Saliva contains digestive enzymes, which may have a degree of digestive action on tissues if they are left in contact . The corner of the mouth is normally exposed to saliva more than any other part of the lips . Reduced lower facial height (vertical dimension or facial support) is usually caused by edentulism (tooth loss), or wearing worn down, old dentures or ones which are not designed optimally . This results in overclosure of the mandible (collapse of the jaws), which extenuates the angular skin folds at the corners of the mouth, in effect creating an intertriginous skin crease . The tendency of saliva to pool in these areas is increased, constantly wetting the area, which may cause tissue maceration and favors the development of a yeast infection . As such, angular cheilitis is more commonly seen in edentulous people (people without any teeth). It is by contrast uncommon in persons who retain their natural teeth . Angular cheilitis is also commonly seen in denture wearers . Angular cheilitis is present in about 30% of people with denture - related stomatitis . It is thought that reduced vertical dimension of the lower face may be a contributing factor in up to 11% of elderly persons with angular cheilitis and in up to 18% of denture wearers who have angular cheilitis . Reduced vertical dimension can also be caused by tooth migration, wearing orthodontic appliances, and elastic tissue damage caused by ultraviolet light exposure and smoking . </P>

What causes the corner of your mouth to crack