In sleep bruxism especially, there is no evidence that removal of occlusal interferences has any impact on the condition. People with no teeth at all who wear dentures can still have bruxism, although dentures also often change the original bite. Most modern sources state that there is no relationship, or at most a minimal relationship, between bruxism and occlusal factors. The findings of one study, which used self-reported tooth grinding rather than clinical examination to detect bruxism, suggested that there may be more of a relationship between occlusal factors and bruxism in children. However, the role of occlusal factors in bruxism cannot be completely discounted due to insufficient evidence and problems with the design of studies. A minority of researchers continue to claim that various adjustments to the mechanics of the bite are capable of curing bruxism (see Occlusal adjustment/reorganization). Psychosocial factors
Many studies have reported significant psychosocial risk factors for bruxism, particularly a stressful lifestyle, and this evidence is growing, but still not conclusive. Some consider emotional stress and anxiety to be the main triggering factors. It has been reported that persons with bruxism respond differently to depression, hostility and stress compared to people without bruxism. Stress has a stronger relationship to awake bruxism, but the role of stress in sleep bruxism is less clear, with some stating that there is no evidence for a relationship with sleep bruxism. However, children with sleep bruxism have been shown to have greater levels of anxiety than other children.
When palpated, the lip may have a texture similar to rubbing the gloved finger along sandpaper.AC may occur with skin lesions of actinic keratosis or skin cancer elsewhere, particularly on the head and neck since these are the most sun exposed areas. Rarely it may represent a genetic susceptibility to light damage (e.g. xeroderma pigmentosum or actinic prurigo). Causes
AC is caused by chronic and excessive exposure to ultraviolet radiation in sunlight. Risk factors include:

Outdoor lifestyle: e.g. farmers, sailors, fishermen, windsurfers, mountaineers, golfers, etc. This has given rise to synonyms for this condition such as "sailors lip" and "farmers lip". The prevalence in agricultural workers in a semi-arid region of Brazil is reported to be 16.7%. Light skin complexion: the condition typically affects individuals with lighter skin tones, particularly Caucasians living in tropical regions. In one report, 96% of persons with AC had phenotype II according to the Fitzpatrick scale. Age: AC typically affects older individuals, and rarely those under the age of 45. Gender: the condition affects males more commonly than females. Sometimes this ratio is reported as high as 10:1.Additional factors may also play a role, including tobacco use, lip irritation, poor oral hygiene, and ill-fitting dentures. Diagnosis
Tissue biopsy is indicated. Prevention
To prevent AC from developing, protective measures could be undertaken such as avoiding mid-day sun, or use of a broad-brimmed hat, lip balm with anti UVA and UVB ingredients (e.g. para-aminobenzoic acid), or sun blocking agents (e.g. zinc oxide, titanium oxide) prior to sun exposure.