STK is extremely common among smokeless tobacco users. Given the association with smokeless tobacco use, this condition tends to occur in adults. A national USA survey estimated an overall prevalence of 1.5% of all types of smokeless tobacco lesions, with males affected more commonly than females.

"Cyclaneusma" is favored by wet, humid, above freezing conditions. This provides adequate conditions for "Cyclaneusma" to thrive in the given environment. A study analyzing "Cyclaneusma" on "Pinus radiata" determined that continuous climate change (global warming) would favor the infection of pines by "Cyclaneusma" because much more of the environment would consist of moderately warm, wet, and humid conditions. Additionally, higher altitude elevations favor "Cyclaneusma" due to the wetter environment.

The high demand for pine trees during the holiday month of December can contribute to the success of "Cyclaneusma". The clustering of pines in a limited area of land enable the disease to spread its ascospores over short distances but through high concentrations of susceptible hosts and therefore poses a problem for Christmas tree production companies. "Cyclaneusma" does not appear to be affected by insect vectors.

Laminated root rot also known as yellow ring rot is caused by the fungal pathogen "Phellinus weirii". Laminated root rot is one of the most damaging root disease amongst conifers in northwestern America and true firs, Douglas-fir, Mountain hemlock, and Western hemlock are highly susceptible to infection with "P. weirii". A few species of plants such as Western white pine and Lodgepole pine are tolerant to the pathogen while Ponderosa pine is resistant to it. Only hardwoods are known to be immune to the pathogen.

Usually this lesion is reversible if the tobacco habit is stopped completely, even after many years of use. In one report, 98% of lesions disappeared within 2 weeks of stopping tobacco use. The risk of the lesion developing into oral cancer (generally squamous cell carcinoma and its variant verrucous carcinoma) is relatively low. Indeed, veruccous carcinoma is sometimes term snuff dipper's cancer. In most reported cases, malignant transformation has occurring in individuals with a very long history of chewing tobacco or who use dry snuff.

Smokeless tobacco use is also accompanied by increased risk of other oral conditions such as dental caries (tooth decay), periodontitis (gum disease), attrition (tooth wear) and staining.

Dental caries is an infectious disease caused primarily by "Streptococcus mutans", characterized by acid demineralization of the enamel, which can progress to further breakdown of the more organic, inner dental tissue (dentin). Everybody is susceptible to caries but the probability of development depends on the patient’s individual disease indicators, risk factors and preventive factors. Factors that are considered high-risk for developing carious lesions on the teeth include:

- Low fluoride exposure

- Time, length, and frequency of sugar consumption

- Quality of tooth cleaning

- Fluctuations in salivary flow rates and composition

- Behavior of the individual

- Socioeconomic status of the individual

- Quality and composition of biofilms

Organic acids released from dental plaque lead to demineralization of the adjacent tooth surface, and consequently to dental caries. Saliva is also unable to penetrate the build-up of plaque and thus cannot act to neutralize the acid produced by the bacteria and remineralize the tooth surface.

Xerostomia is a very common symptom. A conservative estimate of prevalence is about 20% in the general population, with increased prevalences in females (up to 30%) and the elderly (up to 50%).

Cyclaneusma (needle cast) is a fungal disease that is a part of the phylum, Ascomycota. It infects plants that are of pine classification. After infection by "Cyclaneusma", most pines do not display symptoms until 10 months after the initial infection. Symptoms include needles developing yellow spots, horizontal brown bands around the needles, swelling of needles, and off-white fruiting bodies formed on infected needles. Because "Cyclaneusma" is an ascomycete it produces two spore types, an asexual (conidiomata) and sexual (ascomycota) spore. Controlling "Cyclaneusma" has presented a challenge as the disease can survive on both living and dead needles during the winter months. Effective management methods include planting new pines in non-shaded, well drainable soil as well as spraying fungicide. "Cyclaneusma" Needle Cast is an important fungal disease because it directly impacts the commercial value of decorative pines as well as lumber.

The foamy bark canker is a disease affecting oak trees in California caused by the fungus "Geosmithia pallida" and spread by the Western oak bark beetle ("Pseudopityopthorus pubipennis"). This disease is only seen through the symbiosis of the bark beetles and the fungal pathogen. The bark beetles target oak trees and bore holes through the peridermal tissues, making tunnels within the phloem. The fungal spores are brought into these tunnels by the beetles and begin to colonize the damaged cells inside the tunnels. Symptoms of the developing fungus include wet discoloration seeping from the beetle entry holes as the fungus begins to consume phloem and likely other tissues. If bark is removed, necrosis of the phloem can be observed surrounding the entry hole(s). As the disease progresses, a reddish sap and foamy liquid oozes from entry holes, thus giving the disease the name Foamy bark canker. Eventually after the disease has progressed, the tree dies. This disease is important because of its detrimental effects on oak trees and its ability to spread to several new Californian counties in just a couple years.

In all cases of the disease, thorough study of the distribution and intensity should be determined to help choose a management practice that’s cost effective. For example, if the disease is widespread in a pre-commercial stand, destroying the plantation may be the most effective measure. The area can then be replanted with immune or low-susceptible species. Aerial surveying is a viable tool available for use in areas where there are severely damaged systems. Other management tools include:

- Using up to date models to help predict the spread of the disease can help with management choice

- Susceptible species should not be planted within 100 feet of a disease center

- Remove as many infected roots and stumps as possible to avoid inoculation of healthy plants

- Cut all infected trees within the disease center and all uninfected trees within 50 ft of the disease center

- Stumping is an expensive, yet effective measure in gently sloping, high-quality sites with light soils. After an excavator removes the stump, pieces of the root are torn and fragmented so invading soil organisms deter long-term inocula.

- Push-falling is an alternative to post-harvest stumping. Whole trees are pushed over with machinery to expose diseased roots for removal. Push-falling is effective in areas with slopes less than 30 percent and soil textures that are sandy to sandy loam.

- Applications of chemical fumigation (such as chloropicrin) have been unsuccessful in dealing with Laminated root rot.

A tree nut allergy is a hypersensitivity to dietary substances from tree nuts and edible tree seeds causing an overreaction of the immune system which may lead to severe physical symptoms. Tree nuts include, but are not limited to, almonds, Brazil nuts, cashews, chestnuts, filberts/hazelnuts, macadamia nuts, pecans, pistachios, pine nuts, shea nuts and walnuts.

Tree nut allergies are distinct from peanut allergy, as peanuts are legumes, whereas a tree nut is a hard-shelled nut.

Periodontitis is an infection of the gums which leads to bone destruction around the teeth in the jaw. Periodontitis occurs after gingivitis has been established, but not all individuals who have gingivitis will get periodontitis. Plaque accumulation is vital in the progression of periodontitis as the bacteria in plaque release enzymes which attack the bone and cause it to break down, and at the same time osteoclasts in the bone break down the bone as a way to prevent further infection. This can be treated with strict oral hygiene such as tooth brushing and cleaning in between the teeth as well as surgical debridement completed by a dental professional.

The hypothesized causes of meth mouth are a combination of MA side effects and lifestyle factors which may be present in users:

- Dry mouth (xerostomia)

- Clenching and grinding of the teeth (bruxism)

- Infrequent oral hygiene

- Frequent consumption of sugary, fizzy drinks

- Caustic nature of methamphetamine

The dental effects of long-term methamphetamine use are often attributed to its effects on saliva. The reduction in saliva increases the likelihood of dental caries, enamel erosion, and periodontal disease. Although it is clear that use of the drug decreases saliva, the mechanism by which it does so is unclear. One theory is that the drug causes vasoconstriction (narrowing of the blood vessels) in salivary glands, decreasing salivary flow. This constriction is thought to be due to the activation of alpha-adrenergic receptors by both methamphetamine itself and norepinephrine, the levels of which are dramatically increased by methamphetamine use. These factors can be compounded by dehydration, which occurs in many methamphetamine users after drug-induced increases in metabolism. The characteristics of the saliva produced during use of the drug, which includes high protein content, may also contribute to the sensation of dry mouth.

Long-term methamphetamine use can cause parafunctional habits, routine actions of a body part that are different than their common use, which can result in tooth wear and exacerbate periodontal diseases. One such habit that may affect the development of meth mouth is bruxism, particularly as the drug's effects wane and stereotypy occurs, a phase that is often referred to as "tweaking". This bruxism may be due to a drug-induced increase in monoamines. Other behaviors of long-term methamphetamine users that may cause or accelerate the symptoms of meth mouth are the failure to pay attention to oral hygiene and excessive food intake during binges, especially sugary foods; the drug's users often report strong cravings for sugar and consume large amounts of high-sugar beverages. The altered mental state that accompanies methamphetamine use lasts longer than that of some other common drugs, increasing the amount of time the user engages in drug-induced behavior.

Hydrochloric acid is used in methamphetamine's manufacturing process, but academic reviews have not supported the idea that the acid contributes to dental decay. Speculation that oral consumption of the drug causes tooth decay by raising the acidity of users' mouths is also unsupported. Meth mouth is generally most severe in users who inject the drug, rather than those who smoke, ingest or inhale it.

Aside from physiologic causes of xerostomia, iatrogenic effects of medications are the most common cause. A medication which is known to cause xerostomia may be termed "xerogenic". Over 500 medications produce xerostomia as a side effect (see table). Sixty-three percent of the top 200 most commonly prescribed drugs in the United States are xerogenic. The likelihood of xerostomia increases in relation to the total number of medications taken, whether the individual medications are xerogenic or not. The sensation of dryness usually starts shortly after starting the offending medication or after increasing the dose. Anticholinergic, sympathomimetic, or diuretic drugs are usually responsible.

Several drugs may cause AC as a side effect, by various mechanisms, such as creating drug-induced xerostomia. Various examples include isotretinoin, indinavir, and sorafenib. Isotretinoin (Accutane), an analog of vitamin A, is a medication which dries the skin. Less commonly, angular cheilitis is associated with primary hypervitaminosis A, which can occur when large amounts of liver (including cod liver oil and other fish oils) are regularly consumed or as a result from an excess intake of vitamin A in the form of vitamin supplements. Recreational drug users may develop AC. Examples include cocaine, methamphetamines, heroin, and hallucinogens.

Control of the beetle vector is the most effective management technique for disease prevention. Conventional methods of tree thinning and the use of insecticides have been used to combat the western bark beetles, but are only effective before the beetles have colonized and before the fungus has invaded the tree. Other cultural techniques of sanitation and overall health of the oak trees by keeping up with watering, fertilizer or mulch needs, and pruning may help. It is very important to diagnose foamy bark canker disease correctly and promptly in order to manage the disease properly because if a tree is already infected, the removal of the tree is the most effective way to prevent the disease from spreading.

The incidence of the disease is higher in people from certain parts of the world including South-East Asia, South Africa and the Middle East.

Some systemic disorders are involved in angular cheilitis by virtue of their association with malabsorption and the creation of nutritional deficiencies described above. Such examples include people with anorexia nervosa. Other disorders may cause lip enlargement (e.g. orofacial granulomatosis), which alters the local anatomy and extenuates the skin folds at the corners of the mouth. More still may be involved because they affect the immune system, allowing normally harmless organisms like Candida to become pathogenic and cause an infection. Xerostomia (dry mouth) is thought to account for about 5% of cases of AC. Xerostomia itself has many possible causes, but commonly the cause may be side effects of medications, or conditions such as Sjögren's syndrome. Conversely, conditions which cause drooling or sialorrhoea (excessive salivation) can cause angular cheilitis by creating a constant wet environment in the corners of the mouth. About 25% of people with Down syndrome appear to have AC. This is due to relative macroglossia, an apparently large tongue in a small mouth, which may constantly stick out of the mouth causing maceration of the corners of the mouth with saliva. Inflammatory bowel diseases (such as Crohn's disease or ulcerative colitis) can be associated with angular cheilitis. In Crohn's, it is likely the result of malabsorption and immunosuppressive therapy which gives rise to the sores at the corner of the mouth. Glucagonomas are rare pancreatic endocrine tumors which secrete glucagon, and cause a syndrome of dermatitis, glucose intolerance, weight loss and anemia. AC is a common feature of glucagonoma syndrome. Infrequently, angular cheilitis may be one of the manifestations of chronic mucocutaneous candidiasis, and sometimes cases of oropharyngeal or esophageal candidiasis may accompany angular cheilitis. Angular cheilitis may be present in human immunodeficiency virus infection, neutropenia, or diabetes. Angular cheilitis is more common in people with eczema because their skin is more sensitive to irritants. Other conditions possibly associated include plasma cell gingivitis, Melkersson-Rosenthal syndrome, or sideropenic dysphagia (also called Plummer-Vinson syndrome or Paterson-Brown-Kelly syndrome).

Prevention involves an exclusion diet and vigilant avoidance of foods that may be contaminated with tree nuts, nut particles, or oils extracted from nuts. In the United States, the federal Food Allergen Labeling and Consumer Protection Act (FALCPA) requires that any packaged food product that contains tree nuts as an ingredient must list the specific tree nut on the label. Foods that almost always contain tree nuts include pesto, marzipan, Nutella, baklava, pralines, nougat, gianduja, and turrón. Other common foods that may contain tree nuts include cereals, crackers, cookies, baked goods, candy, chocolates, energy/granola bars, flavored coffee, frozen desserts, marinades, barbecue sauces, and some cold cuts, such as mortadella. Tree nut oils (especially shea nut) are also sometimes used in lotions and soaps. Asian and African restaurants, ice cream parlors, and bakeries are considered high-risk for people with tree nut allergy due to the common use of nuts and the possibility of cross contamination.

Xerostomia, also known as dry mouth syndrome, can precipitate dysgeusia because normal salivary flow and concentration are necessary for taste. Injury to the glossopharyngeal nerve can result in dysgeusia. In addition, damage done to the pons, thalamus, and midbrain, all of which compose the gustatory pathway, can be potential factors. In a case study, 22% of patients who were experiencing a bladder obstruction were also suffering from dysgeusia. Dysgeusia was eliminated in 100% of these patients once the obstruction was removed. Although it is uncertain what the relationship between bladder relief and dysgeusia entails, it has been observed that the areas responsible for urinary system and taste in the pons and cerebral cortex in the brain are close in proximity.

Many of the causes for dysgeusia occur due to unknown reasons. A wide range of miscellaneous factors may contribute to this taste disorder, such as gastric reflux, lead poisoning, and diabetes mellitus. A minority of pine nuts can apparently cause taste disturbances, for reasons which are not entirely proven. Certain pesticides can have damaging effects on the taste buds and nerves in the mouth. These pesticides include organochloride compounds and carbamate pesticides. Damage to the peripheral nerves, along with injury to the chorda tympani branch of the facial nerve, also cause dysgeusia. A surgical risk for laryngoscopy and tonsillectomy include dysgeusia. Patients who suffer from the burning mouth syndrome, most likely menopausal women, are often suffering from dysgeusia as well.

There have not been any controlled studies on meth mouth, and several of its aspects are unclear. Although the condition has been popularized by media coverage and case reports, no systematic studies have been conducted to conclusively tie methamphetamine use to symptoms that are commonly described as meth mouth. There are few ties between dental scholars and those who study drug use, and it can be difficult for dental researchers to find methamphetamine users to study.

Whether the drug has a unique effect on dental health has been questioned by a few academics, who note that the long-term use of several other drugs sometimes causes dental problems. Several academic reviews have contradicted this perspective, affirming meth mouth's status as a discrete condition. In favor of its unique status, these reviews cite the differences between methamphetamine-caused caries and those that occur for other reasons, such as cocaine use, as well as the scope of the tooth decay found in some long-term methamphetamine users.

Denture-related stomatitis is common and occurs worldwide. Usually the people affected are middle aged or elderly, with females being affected slightly more commonly than males. Prevalences of up to 70% have been reported in elderly care home residents. It is by far the most common type of oral candidiasis.

There are also a wide variety of drugs that can trigger dysgeusia, including zopiclone, H-antihistamines, such as azelastine and emedastine. Approximately 250 drugs affect taste. The sodium channels linked to taste receptors can be inhibited by amiloride, and the creation of new taste buds and saliva can be impeded by antiproliferative drugs. Saliva can have traces of the drug, giving rise to a metallic flavor in the mouth; examples include lithium carbonate and tetracyclines. Drugs containing sulfhydryl groups, including penicillamine and captopril, may react with zinc and cause deficiency. Metronidazole and chlorhexidine have been found to interact with metal ions that associate with the cell membrane. Drugs that prevent the production of angiotensin II by inhibiting angiotensin converting enzyme, eprosartan for example, have been linked to dysgeusia. There are few case reports claiming calcium channel blockers like Amlodipine also cause dysguesia by blocking calcium sensitive taste buds.

A superior mouth is a mouth that opens upward, with the lower jaw more anterior than the upper jaw. This is an effect typically seen in fish. Some humans are born with this defect, often making their face resemble a shark's. This usually means that the fish feeds from the surface of the body of water in which it dwells.

The major risk factor for the development of this condition is wearing an upper complete denture, particularly when it is not removed during sleep and cleaned regularly. Older dentures are more likely to be involved. Other factors include xerostomia (dry mouth), diabetes or a high carbohydrate diet. Human immunodeficiency virus (HIV) can rarely be an underlying factor.

Wearing dental appliances such as dentures alters the oral microbiota. A microbial plaque composed of bacteria and/or yeasts forms on the fitting surface of the denture (the surface which rests against the palate) and on the mucosa which is covered. Over time, this plaque may be colonized by Candida species. The local environment under a denture is more acidic and less exposed to the cleansing action of saliva, which favors high Candida enzymatic activity and may cause inflammation in the mucosa. "C. albicans" is the most commonly isolated organism, but occasionally bacteria are implicated.

There is controversy as to whether this condition represents a true infection by "C. albicans" or just a reaction to the various micro-organisms present underneath a denture. It has been reported that often the surface of the denture shows positive culture for "Candida" but biospsies of the mucosa rarely show hyphae invading epithelium. Similarly, microbiologic swabs of the involved mucosa show a much less heavy colonization than the surface of the denture. This has led some to conclude that the defining feature of a true infection is absent in denture-related stomatitis.

Poorly fitting dentures may cause pressure on the mucosa and mechanical irritation may create a similar clinical appearance, but this is uncommon. An orthodontic appliance may uncommonly produce a similar result. However, mucosal trauma is thought increase the ability of "C. albicans" to invade the tissues.

Aside from infection and mechanical trauma, inflammatory reactions of the mucosa beneath a denture can also result from irritation or allergy (allergic contact stomatitis) caused by the materials in the denture itself (acrylic, cobalt, chromium), or in response to substances within denture adhesives. Incomplete curing of the acrylic resin (the prosthetic material) may also be an involved factor.

Burning mouth syndrome (BMS) is a burning sensation in the mouth with no underlying dental or medical cause. No related signs of disease are found in the mouth. People with burning mouth syndrome may also have a dry mouth sensation where no cause can be found such as reduced salivary flow, tingling in the mouth, or an altered taste or smell.

A burning sensation in the mouth can be a symptom of another disease when local or systemic factors are found to be implicated, and this is not considered to be burning mouth syndrome, which is a syndrome of medically unexplained symptoms. The International Association for the Study of Pain defines burning mouth syndrome as "a distinctive nosological entity characterized by unremitting oral burning or similar pain in the absence of detectable mucosal changes", and "burning pain in the tongue or other oral mucous membranes", and the International Headache Society defines it as "an intra-oral burning sensation for which no medical or dental cause can be found".

Due to insufficient evidence it is unclear if effective treatments exist.