ANOMALIES OF TOOTH FORMATION & ERUPTION

The Primary & Permanent Dentition are subject to considerable variation in the number , Size & Form of teeth and the structure of the dental tissues.

SUPERNUMERARY TEETH

These are extra teeth that appear in addition to the regular number of teeth.

Also called supplemental or accessory teeth Common region of the jaws to be affected is

the premaxilla.

Cause: A developmental disturbance creating intracellular

activity during the first stage  of tooth development (bud stage) can result in the development of extra teeth. 

Many supernumerary teeth never erupt, but they may delay eruption of nearby teeth or cause other dental problems.   

Treatment: The most common treatment is extraction. This

often needs to be done by an Oral Surgeon when the child reaches the appropriate

Mesiodens Definition: The most common supernumerary tooth is a

mesiodens, which is a mal-formed, peg-like tooth that occurs between the maxillary central incisors.

Cause: A developmental disturbance creating intracellular

activity during the first stage of tooth development (bud stage) can result in the development of extra teeth.

Treatment: The most common treatment is extraction. This often

needs to be done by an Oral Surgeon when the child reaches the appropriate age.

HYPODONTIA Oligodontia, Partial anodontia, or hypodontia

is the congenital absence of one or more teeth. Congenital absence of all wisdom teeth, or third molars, is relatively common.

Cause: Interferences such as radiation exposure or a

hereditary disturbance like ectodermal displaysia can result in this rare condition.

Treatment: Treatment for missing teeth depends on their

location in the mouth.

ABNORMALITIES OF TOOTH SIZE CROWN SIZE: MEGADONTIA: Teeth which exceeds the

normal range of variations, maxillary incisors, mandibular incisors & mand second premolar

MICRODONTIA: Teeth smaller then the normal, may be either of the usual form, or conical/peg shaped.

ROOT SIZE: LARGE ROOT SIZE: Most commonly

associated with permanent canines especially maxillary canines.

SMALL ROOT SIZE: Generalized reduction in root length may be associated with dentine and pulp dysplasias, frequently with a disturbance of root form.

ABNORMALITIES OF TOOTH FORM Concrescence  Definition: Concrescence is a condition where the

cementum (outer covering of the root) overlying the roots of two teeth, joins together.

  Cause:                         The cause can sometimes be

attributed to trauma or crowding of teeth.   Treatment: Surgical separation of the teeth may be necessary if

one is to be extracted.

Fusion  Definition: Fusion is where two developing teeth merge into

one tooth.

  Cause: The phenomenon of tooth fusion arises through

union of two normally separated teeth, and depending upon the stage of development of the teeth at the time of union, it may be either complete or incomplete fusion.  

Treatment: There is a groove that

runs down the back of the tooth that is prone to decay and may necessitate a filling.

Gemination  Definition: Gemination is where a developing tooth splits into

two separate teeth. Cause: The phenomenon of gemination arises when two

teeth develop from one tooth and, as a result, the patient has a larger tooth but a normal number of teeth overall, in contrast to fusion, where the patient would appear to be missing one tooth.

Treatment:        There is a groove that

runs down the back of the tooth that is prone to decay and may necessitate a filling.

It can present a problem if they do not fall out at the right time and interfere with the eruption of the permanent teeth.

Dens Evaginatus Definition: Dens evaginatus, or DE, is a rare dental anomaly

involving an extra cusp or tubercle that protrudes from the tooth.

Premolars are more likely to be affected than any other tooth.

Cause: The exact etiology of this condition is unknown, but is

thought to be a result of genetics or a disruption of the tooth during formation.

Treatment: This condition requires monitoring as the tooth can lose its

blood and nerve supply as a result, and may need root canal treatment.

Talon cusp  Definition: A talon cusp is an extra cusp that resembles an eagle's talon (a

talon is the claw of a bird of prey). A talon cusp appears as a projection from the cingulum of incisor teeth.

They are found rarely in primary teeth. Cause: The exact etiology of this condition is unknown, but is thought to be

a result of   genetics or a disruption of the tooth during formation. Treatment: Large talon cusps can interfere with occlusion; however, grinding

them down is a hazardous endeavor. Talon cusps often contain a prominent pulp horn which is very susceptible to exposure in the younger patient.

This condition requires monitoring as the tooth can lose its blood and nerve supply as a result, and may need root canal treatment.

Dens invaginatus/Dens in dente

  Definition:   Dens invaginatus or dens in dente, means tooth within a

tooth.   Cause: A developmental disturbance in tooth formation resulting

from invagination of the epithelium associated with coronal development into the area that was to be pulp space.

Teeth most affected are maxillary lateral incisors. The malformation shows a broad spectrum of morphologic

variations and frequently results in early pulp necrosis (death).

Treatment: Root canal therapy may be difficult due to the complex

anatomy of the teeth.

Taurodontism Definition: Taurodontism is a morphoanatomical change in the

shape of a tooth, which usually occurs in multirooted teeth. An enlarged body and pulp chamber, as well as apical displacement of the pulpal floor, are characteristic features.

The term means "bull like" teeth. On dental radiograph, the involved tooth looks rectangular in shape without apical taper. The pulp chamber is extremely large and the furcation may be only a few millimeters long at times.

Cause: Conditions associated with

taurodontism: Oral-facial-digital Syndrome Amelogenesis Imperfecta-

Type IV  Down Syndrome Treatment: Endodontic treatment of a

taurodont tooth is challenging, because it requires special care in handling and identifying the number of root canals.

NatalTeeth                                                             Definition: These are extra teeth that are present at birth. Cause: A developmental disturbance creating intracellular

activity during the first stage of tooth development (bud stage) can result in the development of extra teeth.

The most common natal teeth are lower incisors. 

Treatment: These teeth are

defective and their removal is generally recommended, particularly if mobility poses a threat of aspiration. These teeth also make feeding difficult.

Neonatal Teeth Definition: These are primary teeth that erupt

prematurely (during the first few weeks of life).

  Cause: Premature tooth eruption.       

Treatment: These teeth are usually

normal primary teeth and should be retained. An x-ray will be taken if possible to confirm that these are not extra teeth.

Disturbances in Formation Dilaceration  Definition: Dilaceration is a developmental disturbance

in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth.

Cause: The condition is thought to be due to trauma during the

period in which tooth is forming. The result is that the position of the calcified portion of the tooth is changed and the remainder of the tooth is formed at an angle.

The curve or bend may occur anywhere along the length of the tooth, sometimes at the cervical portion, at other times midway along the root or even just at the apex of the root, depending upon the amount of root formed when the injury occurred.

Such an injury to a permanent tooth, resulting in dilaceration, often follows traumatic injury to the deciduous predecessor in which that tooth is driven apically into the jaw.

Treatment: There is no treatment for a tooth with a dilacerated root.

However, teeth with these types of roots make extractions more complex.

Regional odontodysplasia (RO) Definition: RO is a developmental abnormality of teeth, usually

localized to a certain area and nonhereditary. The enamel, dentin, and pulp of teeth are affected, and on radiographs the teeth are described as "ghost teeth".

Cause: The etiology is uncertain; numerous factors have

been suggested and considered as local trauma, irradiation, hypophosphatasia, hypocalcemia, and hyperpyrexia.

It most commonly affects the maxillary anterior teeth of both the permanent and primary dentitions.

Treatment: Most dentists will

advocate extracting the affected teeth as soon as possible and inserting a prosthetic replacement.

Hereditary Disturbances in Structure or Formation Amelogenesis imperfecta  Definition: Amelogenesis imperfecta is an abnormal formation of

the enamel or external layer of teeth.  People afflicted with amelogenesis imperfecta have teeth with abnormal color: yellow, brown or grey. The teeth have a higher risk for dental cavities and are hypersensitive to temperature changes. This disorder can afflict any number of teeth.

Cause: Enamel is composed mostly of mineral that is formed

and regulated by the proteins in it. Amelogenesis Imperfecta is due to the malfunction of the proteins in the enamel.

Treatment: Crowns are sometimes

being used to compensate for the soft enamel.  Usually stainless steel crowns are used in children, which may be replaced by porcelain once they reach adulthood. In the worst case scenario, the teeth may have to be extracted and implants or dentures are required.

Dentinogenesis imperfecta (DI)  Definition: Dentinogenesis imperfecta (hereditary Opalescent

Dentin) is a genetic disorder of tooth development. This condition causes teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent. Teeth are also weaker than normal, making them prone to rapid wear, breakage, and loss. These problems can affect both primary (baby) teeth and permanent teeth.

Classified into three basic types: Shields Type I (associated with Osteogenesis Imperfecta) -

Inherited defect in collagen formation resulting in osteoporotic brittle bones. Primary teeth more affected than permanent teeth. Other features include periapical radiolucencies, bulbous crowns, obliteration of pulp chambers, root fractures and amber translucent tooth color.

Shields Type II (Hereditary Opalescent Dentin) - Primary and permanent dentition are equally affected. Features are same as Shields Type I apart from Osteogenesis Imperfecta.

Shields Type III (Brandywine Type) - Teeth have a shell-like appearance with bell-shaped crowns. Occurs exclusively in a isolated group in Maryland called Brandywine population.

Cause: This condition is inherited in an autosomal dominant pattern, which

means one copy of the altered gene in each cell is sufficient to cause the disorder. Dentinogenesis imperfecta affects an estimated 1 in 6,000 to 8,000 people.

Treatment: Treatment for this condition usually involves placement of crowns

on the teeth, at least in the posterior region. This helps decrease the wear on the teeth and maintains proper vertical dimension between the upper and lower jaws.

For primary teeth, this may mean placement of stainless steel crowns on the posterior teeth and composite resin (tooth colored filling material) for anterior teeth.

Crowns may be necessary for all permanent teeth. Stainless steel crowns and/or composite resin may be used to maintain vertical dimension in the posterior region during maturation.

In general, fillings are not a successful long-term solution because the dentin is so soft. If tooth loss should occur, care should be taken in the fabrication of appliances which may exert pressure on remaining teeth because the roots fracture easily.

With severe cases of DI, the placement of a complete denture over the worn teeth (an overdenture) may be beneficial.

Dentin dysplasia Definition: Dentin dysplasia is a genetic disorder of teeth, commonly

exhibiting an autosomal dominant inheritance. It is characterized by presence of normal enamel but atypical dentin with abnormal pulpal morphology.

There are two types:  Type I is the radicular type, and Type II is the coronal type.

With Type I , the roots of teeth are shorter than normal and the pulp chamber may be nearly gone. The pulp chamber is sometimes described as having a "crescent shaped" appearance.

With Type II , the pulps are enlarged and are described as having a "thistle tube" appearance, in permanent dentition. In the deciduous dentition, coronal dentin dysplasia bears a resemblance to Dentinogenesis Imperfecta type II.

Radiographic Features: Type 1 : Roots are short, blunt and conical. In

deciduous teeth, pulp chambers and root canals are completely obliterated in permanent they may be crescent shaped.

Type 2 : The pulp chamber of the deciduous teeth becomes obliterated in deciduous teeth. While in permanent teeth, large pulp chamber is seen in coronal portion of the tooth - referred to as thistle tube appearance. Pulp stones may be found.

Cause:   Dentin dysplasia is an inherited disorder.

Treatment: Treatment for children with

dentin dysplasia type I is aimed at preventive care. As a result of shortened roots, early loss from periodontitis is frequent. So, meticulous oral hygiene must be established and maintained for the retention of teeth to help children to have natural teeth as long as possible. Oral rehabilitation of prematurely exfoliated teeth is the treatment of choice in future.