Dens evaginatus is a condition found in teeth where the outer surface appears to form an extra bump or cusp. Premolars are more likely to be affected than any other tooth. This may be seen more frequently in Asians, but almost exclusively in Down Syndrome. The pulp of the tooth may extend into the dens evaginatus. There is a risk of the dens evaginatus chipping off in normal function. Hence this condition requires monitoring as the tooth can lose its blood and nerve supply as a result and may need root canal treatment.

1-increased localised pressure.

2- focal growth retardation and stimulation.

Talon Cusp will show physical signs of the irregular dental formation of the teeth and cause other symptoms of the disease that could possibly lead to dental problems in the future depending on severity of the deformity. Most commonly, the extra cusp is located on the lingual surface, giving a three-pronged appearance which has been described as an eagle talon. Rarely however the extra cusp may be situated on the facial surface, or there may be extra cusps on both lingual and facial surfaces. There may be a deep groove between the talon cusp and the rest of the tooth. The extra cusp typically contains pulp tissue. When viewing talon cusp from the occlusal, the projection will appear "x-shaped" as well as appears conical and mimicking the shape of an "eagle's talon".

Symptoms of talon cusp include:

- Interference with occlusion or bite

- Irritation of soft tissues and tongue

- Accidental cusp fracture

- Susceptible to dental caries

Dens invaginatus, also known as dens in dente ("tooth within a tooth") is a condition found in teeth where the outer surface folds inward. There are coronal and radicular forms, with the coronal form being more common.

Dens invaginatus is a malformation of teeth most likely resulting from an infolding of the dental papilla during tooth development or invagination of all layers of the enamel organ in dental papillae. Affected teeth show a deep infolding of enamel and dentine starting from the foramen coecum or even the tip of the cusps and which may extend deep into the root. Teeth most affected are maxillary lateral incisors and bilateral occurrence is not uncommon. The malformation shows a broad spectrum of morphologic variations and frequently results in early pulp necrosis. Root canal therapy may present severe problems because of the complex anatomy of the teeth. Cause, prevalence, classification, and therapeutic considerations including root canal therapy, apical surgery and prevention of pulpal involvement are reviewed.

Talon Cusp is a rare dental anomaly. Generally a person with this develops "cusp-like" projections located on the inside surface of the affected tooth. Talon cusp is an extra cusp on an anterior tooth. Other names for talon cusp is eagle's talon, dens evaginatus, interstitial cusp, tuberculated premolar, evaginated odontoma and supernumerary cusp. Although talon cusp may not appear serious (and in some people may be completely benign), it can cause clinical, diagnostic, functional problems and alters the aesthetic appeal.

The term refers to the same condition as dens evaginatus, but the talon cusp is the manifestation of dens evaginatus on anterior teeth. Talon cusp can simply be defined as hyperplasia of the cingulum of an anterior tooth.Talon cusp was first described by W.H. Mitchell in 1982 and named by J. Kimball Mellor B.S., D.D.S. and Louis W. Ripa, D.D.S., M.S. due to its similar appearance to an eagle's talon. Some sources define a talon cusp as an extra cusp which extends at least half the distance between the cementoenamel junction and the incisal edge of the tooth. Other sources classify all enlarged cingula as talon cusps and classify them according to the degree of enlargement.

The incidence has been found to range from 1% to 6% of the population. Talon cusp tends to occur on permanent teeth only. They are vary rare in (deciduous) baby teeth. In most cases the involved teeth are the permanent maxillary lateral incisors (55%), followed by maxillary central incisors (33%), mandibular incisors (6%), and maxillary canines (4%).

There are two main types: compound and complex.

- A "compound" odontoma still has the three separate dental tissues (enamel, dentin and cementum), but may present a lobulated appearance where there is no definitive demarcation of separate tissues between the individual "toothlets" (or denticles). It usually appears in the anterior maxilla.

- The "complex" type is unrecognizable as dental tissues, usually presenting as a radioopaque area with varying densities. It usually appears in the posterior maxilla or in the mandible.

In addition to the above forms, the dilated odontoma is an infrequent developmental alteration that appears in any area of the dental arches and can affect deciduous, permanent and supernumerary teeth. Dens invaginatus is a developmental anomaly resulting from invagination of a portion of crown forming within the enamel organ during odontogenesis. The most extreme form of dens invaginatus is known as dilated odontoma.

An odontoma (also termed odontome) is a benign tumour of odontogenic origin (i.e. linked to tooth development). Specifically, it is a dental hamartoma, meaning that it is composed of normal dental tissue that has grown in an irregular way.

The average age of people found with an odontoma is 14. The condition is frequently associated with one or more unerupted teeth. Though most cases are found impacted within the jaw there are instances where odontomas have erupted into the oral cavity.

The Jefferson fracture can be associated with this injury, with the C1 ring, or atlas, being fractured in several places, allowing the spine to shift forward relative to the skull base. The Hangman's fracture which is a fracture of the C2 vertebral body or dens of the cervical spine upon which the skull base sits to allow the head to rotate, can also be associated with atlanto-occipital dislocation. Despite its eponym, the fracture is not usually associated with a hanging mechanism of injury.

The injury is immediately fatal in 70% of cases, with an additional 15% surviving to the emergency room, but perishing during their hospital stay. A basion-dental interval of 16mm or greater is associated with mortality. In those with neurologic deficits, survival is unlikely.

The course of fasciolosis in humans has 4 main phases:

- Incubation phase: from the ingestion of metacercariae to the appearance of the first symptoms; time period: few days to 3 months; depends on number of ingested metacercariae and immune status of host

- Invasive or acute phase: fluke migration up to the bile ducts. This phase is a result of mechanical destruction of the hepatic tissue and the peritoneum by migrating juvenile flukes causing localized and or generalized toxic and allergic reactions. The major symptoms of this phase are:

- Fever: usually the first symptom of the disease;

- Abdominal pain

- Gastrointestinal disturbances: loss of appetite, flatulence, nausea, diarrhea

- Urticaria

- Respiratory symptoms (very rare): cough, dyspnoea, chest pain, hemoptysis

- Hepatomegaly and splenomegaly

- Ascites

- Anaemia

- Jaundice

- Latent phase: This phase can last for months or years. The proportion of asymptomatic subjects in this phase is unknown. They are often discovered during family screening after a patient is diagnosed.

- Chronic or obstructive phase:

This phase may develop months or years after initial infection. Adult flukes in the bile ducts cause inflammation and hyperplasia of the epithelium. The resulting cholangitis and cholecystitis, combined with the large body of the flukes, are sufficient to cause mechanical obstruction of the biliary duct. In this phase, biliary colic, epigastric pain, fatty food intolerance, nausea, jaundice, pruritus, right upper-quadrant abdominal tenderness, etc., are clinical manifestations indistinguishable from cholangitis, cholecystitis and cholelithiasis of other origins. Hepatic enlargement may be associated with an enlarged spleen or ascites. In case of obstruction, the gall bladder is usually enlarged and edematous with thickening of the wall (Ref: Hepatobiliary Fascioliasis:

Sonographic and CT Findings in 87 Patients During the InitialPhase and Long-Term Follow-Up. Adnan Kabaalioglu, Kagan Ceken, Emel Alimoglu, Rabin Saba, Metin Cubuk, Gokhan Arslan, Ali Apaydin. AJR 2007; 189:824–828). Fibrous adhesions of the gall bladder to adjacent organs are common. Lithiasis of the bile duct or gall bladder is frequent and the stones are usually small and multiple.

Clinical signs of fasciolosis are always closely associated with infectious dose (amount of ingested metacercariae). In sheep, as the most common definitive host, clinical presentation is divided into 4 types:

- Acute Type I Fasciolosis: infectious dose is more than 5000 ingested metacercariae. Sheep suddenly die without any previous clinical signs. Ascites, abdominal haemorrhage, icterus, pallor of membranes, weakness may be observed in sheep.

- Acute Type II Fasciolosis: infectious dose is 1000-5,000 ingested metacercariae. As above, sheep die but briefly show pallor, loss of condition and ascites.

- Subacute Fasciolosis: infectious dose is 800-1000 ingested metacercariae. Sheep are lethargic, anemic and may die. Weight loss is dominant feature.

- Chronic Fasciolosis: infectious dose is 200-800 ingested metacercariae. Asymptomatic or gradual development of bottle jaw and ascites (ventral edema), emaciation, weight loss.

In blood, anemia, hypoalbuminemia, and eosinophilia may be observed in all types of fasciolosis. Elevation of liver enzyme activities, such a glutamate dehydrogenase (GLDH), gamma-glutamyl transferase (GGT), and lactate dehydrogenase (LDH), is detected in subacute or chronic fasciolosis from 12 to 15 weeks after ingestion of metacercariae. Economical effect of fasciolosis in sheep consists in sudden deaths of animals as well as in reduction of weight gain and wool production. In goats and cattle, the clinical manifestation is similar to sheep. However, acquired resistance to "F. hepatica" infection is well known in adult cattle. Calves are susceptible to disease but in excess of 1000 metacercariae are usually required to cause clinical fasciolosis. In this case the disease is similar to sheep and is characterized by weight loss, anemia, hypoalbuminemia and (after infection with 10,000 metacercariae) death. Importance of cattle fasciolosis consist in economic losses caused by condemnation of livers at slaughter and production losses especially due to reduced weight gain.

In sheep and sometimes cattle, the damaged liver tissue may become infected by the "Clostridium" bacteria "C. novyi" type B. The bacteria will release toxins into the bloodstream resulting in what is known as black disease. There is no cure and death follows quickly. As "C. novyi" is common in the environment, black disease is found wherever populations of liver flukes and sheep overlap.

"Hangman's fracture" is the colloquial name given to a fracture of both pedicles or "pars interarticularis" of the "axis vertebra" (C2).

The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate, in which the notochord (a flexible rod of uniform composition) found in all chordates has been replaced by a segmented series of bones—vertebrae separated by intervertebral discs. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.

There are about 50,000 species of animals that have a vertebral column. The human vertebral column is one of the most-studied examples.

The injury mainly occurs from falls, usually in elderly adults, and motor accidents mainly due to impacts of high force causing extension of the neck and great axial load onto the C2 vertebra.

In a study based in Norway, 60 percent of reported cervical fractures came from falls and 21 percent from motor-related accidents.

According to the Agency for Healthcare Research and Quality (AHRQ), the group under the highest risk of C2 fractures are elderly people within the age group of 65-84 (39.02 percent) at risks of falls (61 percent) or motor accidents (21 percent) in metropolitan areas (94 percent). 203 discharges were from the age group 1-17; 1843 from 18- to 44-year-olds; 2147 from 45- to 64-year-olds, 4890 from 65- to 84-year-olds, and 3440 from 85+-year-olds. Females accounted for 54.45 percent of occurrences while males accounted for the other 45.38 percent.

Excessive or abnormal spinal curvature is classed as a spinal disease or dorsopathy and includes the following abnormal curvatures:

- Kyphosis is an exaggerated kyphotic (concave) curvature in the thoracic region, also called hyperkyphosis. This produces the so-called "humpback" or "dowager's hump", a condition commonly resulting from osteoporosis.

- Lordosis as an exaggerated lordotic (convex) curvature of the lumbar region, is known as lumbar hyperlordosis and also as "swayback". Temporary lordosis is common during pregnancy.

- Scoliosis, lateral curvature, is the most common abnormal curvature, occurring in 0.5% of the population. It is more common among females and may result from unequal growth of the two sides of one or more vertebrae, so that they do not fuse properly. It can also be caused by pulmonary atelectasis (partial or complete deflation of one or more lobes of the lungs) as observed in asthma or pneumothorax.

- Kyphoscoliosis, a combination of kyphosis and scoliosis.

Sylvatic plague is an infectious bacterial disease caused by the bacterium "Yersinia pestis" that primarily affects rodents such as prairie dogs. It is the same bacterium that causes bubonic and pneumonic plague in humans. Sylvatic, or sylvan, means 'occurring in wildlife,' and refers specifically to the form of plague in rural wildlife. Urban plague refers to the form in urban wildlife.

It is primarily transmitted among wildlife through flea bites and contact with infected tissue or fluids. Sylvatic plague is most commonly found in prairie dog colonies and some mustelids like the black-footed ferret.

Sylvatic plague is most commonly found in prairie dog colonies; the flea that feeds on prairie dogs (and other mammals) serves as the vector for transmission to the new host.