Craniomandibular osteopathy, also known as lion's jaw, is a developmental disease in dogs causing extensive bony changes in the mandible and skull. In this disease, a cyclical resorption of normal bone and replacement by immature bone occurs along the inner and outer surfaces of the affected bones. It usually occurs between the ages of 3 and 8 months. Breeds most commonly affected include the West Highland White Terrier, Scottish Terrier, Cairn Terrier, and Boston Terrier. It is rare in large-breed dogs, but it has been reported. Symptoms include firm swelling of the jaw, drooling, pain, and difficulty eating.

It is an inherited disease, especially in Westies, in which it has been recognized as an autosomal recessive trait. Canine distemper has also been indicated as a possible cause, as has "E. coli" infection, which could be why it is seen occasionally in large-breed dogs. Growth of lesions will usually stop around the age of one year, and possibly regress. This timing coincides with the normal completion of endochondral bone growth and ossification. If the disease is extensive, especially around the tympanic bulla (middle ear), then the prognosis is guarded.

A similar disease seen in young Bullmastiffs is known as calvarial hyperostotic syndrome. It is also similar to human infantile cortical hyperostosis. It is characterized by irregular, progressive bony proliferation and thickening of the cortical bone of the calvaria, which is part of the skull. Asymmetry of the lesions may occur, which makes it different from craniomandibular osteopathy. Symptoms include painful swelling of the skull, fever, and lymph node swelling. In most cases it is self-limiting.

Osteochondrodysplasia is a general term for a disorder of the development of bone and cartilage.

A bone disease is also called an "osteopathy", but because the term osteopathy is often used to refer to an alternative health-care philosophy, use of the term can cause some confusion.

Osteochondropathy refers to a disease ("-pathy") of the bone and cartilage.

However, it is more common to refer to these conditions as one of the following:

- chondropathy (disease of the cartilage)

- A bone disease is also called an "osteopathy", but because the term osteopathy is often used to describe a healthcare approach, use of the term can cause some confusion.

A periosteal reaction is the formation of new bone in response to injury or other stimuli of the periosteum surrounding the bone. It is most often identified on X-ray films of the bones.

A periosteal reaction can result from a large number of causes, including injury and chronic irritation due to a medical condition such as hypertrophic osteopathy, bone healing in response to fracture, chronic stress injuries, subperiosteal hematomas, osteomyelitis, and cancer of the bone. It may also occur as part of thyroid acropachy, a severe sign of the autoimmune thyroid disorder Grave's disease.

Other causes include Menkes kinky hair syndrome and hypervitaminosis A.

It can take about three weeks to appear.

Occlusal factors as an etiologic factor in TMD is a controversial topic. Abnormalities of occlusion (problems with the bite) are often blamed for TMD but there is no evidence that these factors are involved. Occlusal abnormalities are incredibly common, and most people with occlusal abnormalities do not have TMD. Although occlusal features may affect observed electrical activity in masticatory muscles, there are no statistically significant differences in the number of occlusal abnormalities in people with TMD and in people without TMD. There is also no evidence for a causal link between orthodontic treatment and TMD. The modern, mainstream view is that the vast majority of people with TMD, occlusal factors are not related. Theories of occlusal factors in TMD are largely of historical interest. A causal relationship between occlusal factors and TMD was championed by Ramfjord in the 1960s. A small minority of dentists continue to prescribe occlusal adjustments in the belief that this will prevent or treat TMD despite the existence of systematic reviews of the subject which state that there is no evidence for such practices, and the vast majority of opinion being that no irreversible treatment should be carried out in TMD (see Occlusal adjustment).

TMD does not obviously run in families like a genetic disease. It has been suggested that a genetic predisposition for developing TMD (and chronic pain syndromes generally) could exist. This has been postulated to be explained by variations of the gene which codes for the enzyme catechol-O-methyl transferase (COMT) which may produce 3 different phenotypes with regards pain sensitivity. COMT (together with monoamine oxidase) is involved in breaking down catecholamines (e.g. dopamine, epinephrine, and norepinephrine). The variation of the COMT gene which produces less of this enzyme is associated with a high sensitivity to pain. Females with this variation, are at 2–3 times greater risk of developing TMD than females without this variant. However this theory is controversial since there is conflicting evidence.

Spondylosis is caused from years of constant abnormal pressure, from joint subluxation, sports, or poor posture, being placed on the vertebrae, and the discs between them. The abnormal stress causes the body to form new bone in order to compensate for the new weight distribution. This abnormal weight bearing from bone displacement will cause spondylosis to occur. Poor postures and loss of the normal spinal curves can lead to spondylosis as well. Spondylosis can affect a person at any age; however, older people are more susceptible.

Spondylosis is a broad term meaning degeneration of the spinal column from any cause. In the more narrow sense it refers to spinal osteoarthrosis, the age-related wear and tear of the spinal column, which is the most common cause of spondylosis. The degenerative process in osteoarthritis chiefly affects the vertebral bodies, the neural foramina and the facet joints (facet syndrome). If severe, it may cause pressure on the spinal cord or nerve roots with subsequent sensory or motor disturbances, such as pain, paresthesia, imbalance, and muscle weakness in the limbs.

When the space between two adjacent vertebrae narrows, compression of a nerve root emerging from the spinal cord may result in radiculopathy (sensory and motor disturbances, such as severe pain in the neck, shoulder, arm, back, or leg, accompanied by muscle weakness). Less commonly, direct pressure on the spinal cord (typically in the cervical spine) may result in myelopathy, characterized by global weakness, gait dysfunction, loss of balance, and loss of bowel or bladder control. The patient may experience shocks (paresthesia) in hands and legs because of nerve compression and lack of blood flow. If vertebrae of the neck are involved it is labelled cervical spondylosis. Lower back spondylosis is labeled lumbar spondylosis. The term is from Ancient Greek σπόνδυλος "spóndylos", "a vertebra", in plural "vertebrae – the backbone".

There are many causes of TOS. The most frequent cause is trauma, either sudden (as in a clavicle fracture caused by a car accident), or repetitive (as in a legal secretary who works with his/her hands, wrists, and arms at a fast paced desk station with non-ergonomic posture for many years). TOS is also found in certain occupations involving lots of lifting of the arms and repetitive use of the wrists and arms.

One cause of arterial compression is trauma, and a recent case involving fracture of the clavicle has been reported.

The two groups of people most likely to develop TOS are those suffering from neck injuries due to traffic accidents and those who use computers in non-ergonomic postures for extended periods of time. TOS is frequently a repetitive stress injury (RSI) caused by certain types of work environments. Other groups which may develop TOS are athletes who frequently raise their arms above the head (such as swimmers, volleyball players, dancers, badminton players, baseball pitchers, and weightlifters), rock climbers, electricians who work long hours with their hands above their heads, and some musicians.

Focal infection theory is the historical concept that many chronic diseases, including systemic and common ones, are caused by focal infections. In present medical consensus, a focal infection is a localized infection, often asymptomatic, that causes disease elsewhere in the host, but focal infections are fairly infrequent and limited to fairly uncommon diseases. (Distant injury is focal infection's key principle, whereas in ordinary infectious disease, the infection itself is systemic, as in measles, or the initially infected site is readily identifiable and invasion progresses contiguously, as in gangrene.) Focal infection theory, rather, so explained virtually all diseases, including arthritis, atherosclerosis, cancer, and mental illnesses.

An ancient concept that took modern form around 1900, focal infection theory was widely accepted in medicine by the 1920s. In the theory, the "focus of infection" might lead to secondary infections at sites particularly susceptible to such microbial species or toxin. Commonly alleged foci were diverse—appendix, urinary bladder, gall bladder, kidney, liver, prostate, and nasal sinuses—but most commonly were oral. Besides dental decay and infected tonsils, both dental restorations and especially endodontically treated teeth were blamed as foci. The putative "oral sepsis" was countered by tonsillectomies and tooth extractions, including of endodontically treated teeth and even of apparently healthy teeth, newly popular approaches—sometimes leaving individuals toothless—to treat or prevent diverse diseases.

Drawing severe criticism in the 1930s, focal infection theory—whose popularity zealously exceeded consensus evidence—was discredited in the 1940s by research attacks that drew overwhelming consensus of this sweeping theory's falsity. Thereupon, dental restorations and endodontic therapy became again favored. Untreated endodontic "disease" retained mainstream recognition as fostering systemic disease. But only alternative medicine and later biological dentistry continued highlighting sites of dental treatment—still endodontic therapy, but, more recently, also dental implant, and even tooth extraction, too—as foci of infection causing chronic and systemic diseases. In mainstream dentistry and medicine, the primary recognition of focal infection is endocarditis, if oral bacteria enter blood and infect the heart, perhaps its valves.

Entering the 21st century, scientific evidence supporting general relevance of focal infections remained slim, yet evolved understandings of disease mechanisms had established a third possible mechanism—altogether, metastasis of infection, metastatic toxic injury, and, as recently revealed, metastatic immunologic injury—that might occur simultaneously and even interact. Meanwhile, focal infection theory has gained renewed attention, as dental infections apparently are widespread and significant contributors to systemic diseases, although mainstream attention is on ordinary periodontal disease, not on hypotheses of stealth infections via dental "treatment". Despite some doubts renewed in the 1990s by conventional dentistry's critics, dentistry scholars maintain that endodontic therapy can be performed without creating focal infections.

TOS can be attributed to one or more of the following factors:

- Congenital abnormalities are frequently found in persons with TOS. These include cervical rib, prolonged transverse process, and muscular abnormalities (e.g., in the scalenus anterior muscle, a sickle-shaped scalenus medius) or fibrous connective tissue anomalies.

- Trauma (e.g., whiplash injuries) or repetitive strain is frequently implicated.

- Rarer acquired causes include tumors, hyperostosis, and osteomyelitis

In some cases Meige's syndrome can be reversed when it is caused by medication. It has been theorized that it is related to cranio-mandibular orthopedic misalignment, a condition that has been shown to cause a number of other movement disorders (Parkinon's, tourettes, and torticollis). This theory is supported by the fact that the trigeminal nerve is sensory for blink reflex, and becomes hypertonic with craniomandibular dysfunction. Palliative treatments are available, such as botulinum toxin injections.

During the 1980s, dentist Hal Huggins, sparking severe controversy, spawned biological dentistry, which claims that conventional tooth extraction routinely leaves within the tooth socket the periodontal ligament that often becomes gangrenous, then, forming a jawbone "cavitation" seeping infectious and toxic material. Sometimes forming elsewhere in bones after injury or ischemia, jawbone cavitations are recognized as foci also in osteopathy and in alternative medicine, but conventional dentists generally conclude them to be nonexistent. Although the International Academy of Oral Medicine & Toxicology claims that the scientific evidence establishing the existence of jawbone cavitations is overwhelming, and even published in textbooks, the diagnosis and related treatment remain controversial, and allegations of quackery persist.

Huggins and many biological dentists also espouse Weston Price's findings on endodontically treated teeth routinely being foci of infection, although these dentists have been accused of quackery. Conventional belief is that microorganisms within inaccessible regions of a tooth's roots are rendered harmless once entrapped by the filling material, although little evidence supports this. A H Rogers in 1976 and E H Ehrmann in 1977 had dismissed any relation between endodontics and focal infection. At dentist George Meinig's 1994 book, "Root Canal Cover-Up Exposed", discussing researches of Rosenow and of Price, some dentistry scholars reasserted that the claims were evaluated and disproved by the 1940s. Yet Meinig was but one of at least three authors who in the early 1990s independently renewed the concern.

Boyd Haley and Curt Pendergrass found especially high levels of bacterial toxins in root-filled teeth. Although such possibility appears especially likely amid compromised immunity—as in individuals cirrhotic, asplenic, elderly, rheumatoid arthritic, or using steroid drugs—there remained a lack of carefully controlled studies definitely establishing adverse systemic effects. Conversely, some if few studies have investigated effects of systemic disease on root-canal therapy's outcomes, which tend to worsen with poor glycemic control, perhaps via impaired immune response, a factor largely ignored until recently, but now recognized as important. Still, even by 2010, "the potential association between systemic health and root canal therapy has been strongly disputed by dental governing bodies and there remains little evidence to substantiate the claims".

The traditional root-filling material is gutta-percha, whereas a new material, Biocalex, drew initial optimism even in alternative dentistry, but Biocalex-filled teeth were later reported by Boyd Haley to likewise seep toxic byproducts of anaerobic bacterial metabolism. Seeking to sterilize the tooth interior, some dentists, both alternative and conventional, have applied laser technology. Although endodontic therapy can fail and eventually often does, dentistry scholars maintain that it "can" be performed without creating focal infections. And even by 2010, molecular methods had rendered no consensus reports of bacteremia traced to asymptomatic endodontic infection. In any event, the predominant view is that shunning endodonthic therapy or routinely extracting endodontically treated teeth to treat or prevent systemic diseases remains unscientific and misguided.

The main symptoms involve involuntary blinking and chin thrusting. Some patients may experience excessive tongue protrusion, squinting, light sensitivity, muddled speech, or uncontrollable contraction of the platysma muscle. Some Meige's patients also have "laryngeal dystonia" (spasms of the larynx). Blepharospasm may lead to embarrassment in social situations, and oromandibular dystonia can affect speech, making it difficult to carry on the simplest conversations. This can cause difficulty in both personal and professional contexts, and in some cases may cause patients to withdraw from social situations.

The condition tends to affect women more frequently than men.