The cause of talon cusp is unknown. The anomaly can occur due to genetic and environmental factors but the onset can be spontaneous. Prevention is difficult because the occurrence happens during the development of teeth.

Talon cusp affects men and women equally, however the majority of reported cases are of the male gender. Individuals of Asian, Arabic, Native American and Inuit descent are affected more commonly. Talon cusp is also highly observed in patients with orofacial digital II syndrome and Rubinstein Taybi syndrome. Other anomalies that occur with talon cusp can include peg laterals, supernumerary teeth, dens envaginatus, agenesis and impaction. A person belonging to one of these particular demographics or one who has any of these deformities or syndromes may have a higher risk of having a talon cusp.

Future studies will look further into the relationship of talon cusp and Rubinstein-Taybi syndrome and other oral-facial-digital syndromes. A former study showed a direct correlation in which 45 affected patients with Rubinstein-Taybi syndrome, 92% of these patients had talon cusp. Other researchers are attempting to trace talon cusp to ancestors and comparing dentition to modern humans. Another study done in 2007 examined the dentition of 301 Native American Indian skeletons for the presence or absence of talon cusp. The results showed five skeletons (2 percent) in the population had the trait.

In 2011, only 21 cases of talon cusp have been reported and are in literature. It appears that as of 2014 and 2015, additional research continues in hopes of finding the cause and mechanism of talon cusp. With the majority of cases of talon cusp being unreported, it remains difficult to conduct tests, come up with conclusions, conduct surgery and perform research with small numbers.

The cause of isolated missing teeth remains unclear, but the condition is believed to be associated with genetic or environmental factors during dental development. Missing teeth have been reported in association with increased maternal age, low birth weight, multiple births and rubella virus infection during embryonic life.

There is a possible correlation between tooth agenesis and innervation. A relationship was also postulated between abnormalities of the brainstem and the presence of agenesis.

Hypodontia is often familial, and can also be associated with genetic disorders such as ectodermal dysplasia or Down syndrome. Hypodontia can also be seen in people with cleft lip and palate.

Among the possible causes are mentioned genetic, hormonal, environmental and infectious.

Cause due to hormonal defects: idiopathic hypoparathyroidism and pseudohypoparathyroidism. Exists the possibility that this defect depends on a moniliasis (candidiasis, "candida endocrinopathy syndrome").

Environmental causes involving exposure to PCBs (ex.dioxin), radiation, anticancer chemotherapeutic agents, allergy and toxic epidermal necrolysis after drug.

Infectious causes of hypodontia: rubella, candida.

The Journal of the American Dental Association published preliminary data suggesting a statistical association between hypodontia of the permanent teeth and epithelial ovarian cancer (EOC). The study shows that women with EOC are 8.1 times more likely to have hypodontia than are women without EOC. The suggestion therefore is that hypodontia can serve as a "marker" for potential risk of EOC in women.

Also the increased frequency of hypodontia in twins and low birth weight in twins with hypodontia suggests that environmental factors during perinatal are responsible hypodontia.

Females are affected more than males, and the condition occurs in permanent (adult) teeth more than deciduous (baby teeth or milk teeth).

Because MLIA can be detected from partial skeletal remains, it is useful in the field of anthropology. Anthropologically-interesting human remains often have relatively well preserved skeletons, but no soft tissues or intact DNA. This makes it hard to determine relationships between the deceased individuals. MLIA is sometimes related to inbreeding, so the presence of MLIA in many members of a large collection of remains can indicate that the population that lived there was relatively inbred. This technique has been used to study a group of Neolithic farmers.

Genetic causes also involve the genes MSX1 and PAX9.

Genetic associations for selective tooth agenesis ("STHAG") include:

Maxillary lateral incisor agenesis (MLIA) is lack of development (agenesis) of one or both of the maxillary lateral incisor teeth. In normal human dentition, this would be the second tooth on either side from the center of the top row of teeth. The condition is bilateral if the incisor is absent on both sides or unilateral if only one is smissing. It appears to have a genetic component.

There are many potential factors involved.

- Congenital hypopituitarism

- Ectodermal dysplasia

- Down syndrome

- Ionizing radiation to the jaws during tooth development (odontogenesis)

- Chemotherapy during tooth development

- Marshall syndrome

- Rieger syndrome

- Focal dermal hypoplasia

- Silver-Russell syndrome

- Williams syndrome

- Gorlin-Chaudhry-Moss syndrome

- Coffin–Siris syndrome

- Salamon syndrome

- Cleft lip and palate

Others include trichorhinopharyngeal, odontotrichomelic, neuroectodermal and dermo-odontodysplasia syndromes.

There is still some discussion on whether FND is sporadic or genetic. The majority of FND cases are sporadic. Yet, some studies describe families with multiple members with FND. Gene mutations are likely to play an important role in the cause. Unfortunately, the genetic cause for most types of FND remains undetermined.

OAFNS is a combination of FND and oculo-auriculo-vertebral spectrum (OAVS).

The diagnosis of OAVS is based on the following facial characteristics: microtia (underdeveloped external ear), preauricular tags, facial asymmetry, mandibular hypoplasia and epibulbar lipodermoids (benign tumor of the eye which consists of adipose and fibrous tissue).

There still remains discussion about the classification and the minimal amount of characteristics. When someone presents with FND and the characteristics of OAVS, the diagnosis OAFNS may be made.

As the incidence of OAFNS is unknown, there are probably a lot of children with mild phenotypes that aren’t being diagnosed as being OAFNS.

The cause of OAFNS is unknown, but there are some theories about the genesis. Autosomal recessive inheritance is suggested because of a case with two affected siblings and a case with consanguineous parents. However, another study shows that it is more plausible that OAFNS is sporadic.

It is known that maternal diabetes plays a role in developing malformations of craniofacial structures and in OAVS. Therefore, it is suggested as a cause of OAFNS. Folate deficiency is also suggested as possible mechanism.

Low-dose CT protocols should be considered in diagnosing children with OAFNS.

In disease states, maxillary prognathism is associated with Cornelia de Lange syndrome; however, so-called false maxillary prognathism, or more accurately, retrognathism, where there is a lack of growth of the mandible, is by far a more common condition.

Prognathism, if not extremely severe, can be treated in growing patients with orthodontic functional or orthopaedic appliances. In adult patients this condition can be corrected by means of a combined surgical/orthodontic treatment, where most of the time a mandibular advancement is performed. The same can be said for mandibular prognathism.

Macrostomia, (from the Greek prefix "makro-" meaning "large" and from Greek , "mouth") refers to a mouth that is unusually wide.

Macrostomia is characterized as a physical abnormality that causes clefts to form on the face of affected individuals. These clefts can form on either or both sides of the face, but they are most commonly seen on the right cheek and have a higher rate of occurrence in males. Macrostomia is very irregular and on average occurs only once in every 150,000 to 300,000 live births. It's unusual for macrostomia to occur on its own and it is included as a symptom for many diseases including craniofacial microsomia. The clefts result from improper development and fusion of the mandibular and maxillary processes. The clefts cause problems with facial muscle development. The origin of macrostomia is not yet fully understood it could have multiple causes.

Because the cause of facial clefts still is unclear, it is difficult to say what may prevent children being born with facial clefts. It seems that folic acid contributes to lowering the risk of a child being born with a facial cleft.

Not all alveolar prognathism is anomalous, and significant differences can be observed among different ethnic groups.

Harmful habits such as thumb sucking or tongue thrusting can result in or exaggerate an alveolar prognathism, causing teeth to misalign. Functional appliances can be used in growing children to help modify bad habits and neuro-muscular function, with the aim of correcting this condition.

Alveolar prognathism can also easily be corrected with fixed orthodontic therapy. However, relapse is quite common, unless the cause is removed or a long-term retention is used.

Likely due to the complexity of macrostomia, many theories have been provided over time in an attempt to define its origin. There is no definitive mechanism to explain its development but it is likely that there are interactions between genes and the environment resulting in improper development of the first and sometimes second brachial arch.

It can be caused by any of the following:

- Nutritional factors.

- Some diseases (such as undiagnosed and untreated celiac disease, chicken pox, congenital syphilis).

- Hypocalcemia.

- Fluoride ingestion (dental fluorosis).

- Birth injury.

- Preterm birth.

- Infection.

- Trauma from a deciduous tooth.

Turner's hypoplasia is an abnormality found in teeth. Its appearance is variable, though usually is manifested as a portion of missing or diminished enamel on permanent teeth. Unlike other abnormalities which affect a vast number of teeth, Turner's hypoplasia usually affects only one tooth in the mouth and, it is referred to as a Turner's tooth.

A facial cleft is an opening or gap in the face, or a malformation of a part of the face. Facial clefts is a collective term for all sorts of clefts. All structures like bone, soft tissue, skin etc. can be affected. Facial clefts are extremely rare congenital anomalies. There are many variations of a type of clefting and classifications are needed to describe and classify all types of clefting. Facial clefts hardly ever occur isolated; most of the time there is an overlap of adjacent facial clefts.

Literature states that very few crossbites tend to self-correct which often justify the treatment approach of correcting these bites as early as possible. Only 0–9% of crossbites self-correct. Lindner et al. reported that in a 50% of crossbites were corrected in 76 four year old children.

Behavior therapy is important especially when the kids are in their primary dentition in the pre-adolescent age. Improving habits at this time may lead to self-correction of open bite in many cases. Sometimes presence of infantile swallowing into early childhood may lead to an anterior open bite in patients. Habit control through appliances such as Tongue crib or Tongue spurs may be used in adolescent ages if the behavior modification fails to stop the habit.

There is no single factor that is consistently found in the prenatal history of individuals affected with amyoplasia and, in some cases, there is no known cause of the disorder.

Amyoplasia is a sporadic condition that occurs due to lack of fetal movement in the womb. There is no specific gene that is known to cause the disorder. It is thought to be multifactorial, meaning that numerous genes and environmental factors play a role in its development. The recurrence risk is minimal for siblings or children of affected individuals. There have been no reports of recurrent cases of amyoplasia in a family.

The fetal akinesia in amyoplasia is thought to be caused by various maternal and fetal abnormalities. In some cases, the mother's uterus does not allow for adequate fetal movement because of a lack of amniotic fluid, known as oligohydramnios, or an abnormal shape to the uterus, called a bicornuate uterus.

There may also be a myogenic cause to the fetal akinesia, meaning that fetal muscles do not develop properly due to a muscle disease (for example, a congenital muscular dystrophy). Similarly, connective tissue tendon and skeletal defects may contribute to the fetal akinesia and be the primary cause of amyoplasia. Additionally, malformations may occur in the central nervous system and/or spinal cord that can lead to a lack of fetal movement in utero. This neurogenic cause is often accompanied by a wide range of other conditions. Other causes of fetal akinesia may include a maternal fever during pregnancy or a virus.

Another abnormal condition is hypodontia, in which there are fewer than the usual number of teeth.

Hyperdontia is seen in a number of disorders, including Gardner's syndrome and cleidocranial dysostosis, where multiple supernumerary teeth are seen that are usually impacted.

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.

The presence of a supernumerary tooth, particularly when seen in young children, is associated with a disturbance of the maxillary incisor region. This commonly results in the impaction of the incisors during the mixed dentition stage. The study debating this also considered many other factors such as: the patient’s age, number, morphology, growth orientation and position of the supernumerary tooth. Therefore, the presence of a supernumerary tooth when found must be appropriately approached with the correct treatment plan incorporating the likelihood of incisal crowding.

Caudal regression syndrome or sacral agenesis (or hypoplasia of the sacrum) is a congenital disorder in which there is abnormal fetal development of the lower spine—the caudal partition of the spine.

It occurs at a rate of approximately one per 25,000 live births.