Developmental Disorders of Teeth

176
DEPARTMENT OF ORAL AND MAXILLOFACIAL PATHOLOGY

Transcript of Developmental Disorders of Teeth

Page 1: Developmental Disorders of Teeth

DEPARTMENT OF ORAL AND MAXILLOFACIAL PATHOLOGY

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Developmental disorders of teeth

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Contents

• Disturbances in Number• Disturbances in Size of Teeth

Disturbances in Position of Teeth• Disturbances in Eruption• Disturbances in Shape of Teeth

• Disturbances in Formation

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• Classification

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• Disturbances in Number• Anodontia• Hypodontia• Hyperdontia

• Disturbances in Size of Teeth• Microdontia• Macrodontia

• Disturbances in Position of Teeth• Transposition• Translocation• Abnormal sites in the body

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• Disturbances in Eruption• Premature Eruption

• Natal teeth• Epstein’s pearl /

Bohn’s nodules• Delayed eruption

• Impacted Teeth• Un-erupted teeth

• Post-permanent dentition

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• Disturbances in Shape of Teeth• Fusion / Gemination / Twinning• Peg-shaped teeth• Taurodontism• Dilaceration of crown and roots• Supernumerary cusps and

grooves• Dens in dente • Supernumerary roots• Rhizomegaly• Rhizomicry

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Disturbances in structure of tooth • Enamel : Amelogenesis imperfecta, Enamel

hypoplasia

• Dentin: Dentinogenesis imperfecta, Dentin dyspalsia, Dentin hypocalification

• Enamel and dentin: • Regional odontodysplasia

• Pulp: pulp calcifications

• Cementum: • Cemental hypoplasia• Cemental Hypocalcification• Cemental excrescenses (spikes and

exostoses)

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Disturbances in Number

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Anodontia

• Anodontia is the congenital absence of teeth.

• Anodontia means the failure of teeth to form at all. may be of two types, total and partial.

• In true (or total) anodontia, all teeth fail to develop.

• Total anodontia is an extremely rare occurrence. When this does occur, it is usually part of a more generalized disorder ectodermal dysplasia, an inherited defect of all ectodermally derived structures.

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Total anodontia

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• Induced or false anodontia occurs as a result of extraction of all teeth

• The term pseudoanodontia is applied to multiple unerupted teeth.

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Hypodontia (Partial Anodontia)

• Partial anodontia is the failure of one or more teeth to develop.

• It is much more common than complete anodontia. Third molars, lower second premolars, and upper lateral incisors (in that order) are the most common congenitally absent teeth.

• The overall frequency of patients with congenitally missing teeth (excluding third molars) has ranged from 1.6 –9.6 per cent.

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• congenital absence of a deciduous tooth is not common. When it does occur, it is most often the upper lateral incisor that is absent. When a deciduous tooth is absent, its permanent successor is usually missing also.

• Genetic factor

• Terms such as oligodontia or hypodontia are occasionally used in British journals to describe the condition of partial anodontia.

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• Grabber reported that it is actually the result of one or more point mutations in a closely linked polygenic system, most often transmitted in an autosomal dominant pattern with incomplete penetrance and variable expressivity.

• Some investigators believe cases of missing third molars to be evidence of an evolutionary trend toward fewer teeth.

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• Syndromes associated with hypodontia:

Cranio-oculo-dental Crouzon Down Ectodermal dysplasia Ehler-danlos Focal dermal hypoplasia Gorlin Hurler Progeria Sturge-Weber Turner

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Hyperodontia (Supernumerary Teeth)

• A supernumerary tooth is one that is additional to the normal series and can be found in almost any region of the dental arch.

• Most (90%) occur in the maxilla. Their presence in the deciduous dentition is quite rare. Two terms occasionally used to describe this condition of having extra teeth are polydontia or hyperdontia.

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• A supernumerary teeth may closely resemble the teeth of the group to which it belongs, or it may bear little resemblance in size or shape to the teeth with which it is associated.

• It has been suggested that supernumerary teeth develop from splitting of the permanent bud itself.

• Another theory, is the hyperactivity theory, which suggests that supernumeraries are formed as a result of local, independent, conditioned hyperactivity of the dental lamina.

• In some cases there appears to be a hereditary tendency for the development of supernumerary teeth.

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• The etiology is not completely understood.

• Brook found that supernumerary teeth were present in 0.8 per cent of primary dentitions and in 2.1 per cent permanent dentitions.

• Occurrence may be single or multiple, unilateral or bilateral, erupted or impacted, and in one or both jaws.

• Supernumerary teeth associated with cleft lip and palate result from fragementation of the dental lamina during cleft formation.

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• Most supernumerary teeth do not erupt.

• Their presence may give rise to a variety of clinical problems.

• Detection of supernumerary teeth is best achieved by thorough clinical and radiographic examination.

• Their management should form part of a comprehensive treatment plan.

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• The conditions commonly associated with an increased prevalence of supernumerary teeth include cleft lip and palate, cleidocranial dysplasia and Gardner syndrome.

OPG of patient with cleidocranial dysplasia

showing multiple supernumerary teeth

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• The frequency of supernumerary permanent teeth in the cleft area in children with unilateral cleft lip or palate or both was found to be 22.2 per cent.

• The frequency of supernumeraries in patients with cleidocranial dysplasia ranged from 22 per cent in the maxillary incisor region to 5 per cent in the molar region.

• No significant gender predilection in primary supernumerary teeth

• Males are affected approximately twice as frequently as females in the permanent dentition.

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They are classified according to their form and location.

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Conical

• Mesiodens : This small peg-shaped conical tooth is the supernumerary most commonly found in the permanent dentition.

• It develops with root formation ahead of or at an equivalent stage to that of permanent incisors

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• It may occasionally be found high and inverted into the palate or in a horizontal position. In most cases, however, the long axis of the tooth is normally inclined.

• The conical supernumerary can result in rotation or displacement of the permanent incisor, but rarely delays eruption.

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Tuberculate

• The tuberculate type of supernumerary possesses more than one cusp or tubercle.

• It is frequently described as barrel-shaped and may be invaginated.

• Root formation is delayed compared to that of the permanent incisors.

• Tuberculate supernumeraries are often paired and are commonly located on the palatal aspect of the central incisors.

• They rarely erupt and are frequently associated with delayed eruption of the incisors

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Supplemental

• The supplemental supernumerary refers to a duplication of teeth in the normal series and is found at the end of a tooth series .

• The most common supplemental tooth is the permanent maxillary lateral incisor, but supplemental premolars and molars also occur.

• The majority of supernumeraries found in the primary dentition are of the supplemental type and seldom remain impacted.

Supplemental mandibular premolars

with follicular enlargement.

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Paired tuberculate supernumeraries with associated eruption disturbances

Failure of eruption of maxillary central incisors

associated with the paired

tuberculate supernumeraries

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• Distomolars- distal to exisiting 3rd molars; also called 4th molars

• Paramolars – supernumerary teeth on the buccal or palatal aspects of molars; may be isolated or fused to existing molars

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Odontoma

• 4th category of supernumerary tooth. However, this category is not universally accepted.

• The term “odontoma” refers to any tumor of odontogenic origin.

• Most authorities, however, accept the view that the odontoma represents a hamartomatous malformation rather than a neoplasm.

Periapical radiograph of

complex composite odontoma.

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• Syndrome associated with hyperdontia- Apert Cleidocranial dysplasia Crouzon Down Ehler-danlos Gardner Sturge-Weber

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Disturbances in Size of Teeth

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Microdontia (small teeth)

Three types of microdontia are recognized:

• True generalized microdontia - All teeth are normally formed but smaller than normal. Occurs in pituitary dwarfism.

• Relative generalized microdontia - Normal or slightly smaller teeth present in jaws that are larger than normal.

• Localized microdontia - Usually only one tooth is involved. Affects maxillary lateral incisors and third molars

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• Conditions Associated with Microdontia• Down’s Syndrome (peg laterals)• Ectodermal Dysplasia• Chondroectodermal Dysplasia (Ellis-

van Creveld Syndrome) • Hemifacial Microsomia (Goldenhar

Syndrome)

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Chondroectodermal Dysplasia (Ellis-van Creveld Syndrome)

• Inheritance:• Autosomal recessive

Clinical Features:• Chondrodysplasia 

Polydactyly  Hypoplastic nails with koilonychia  Short and thick limbs  Congenital heart disease (50%)

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Oral/Facial Features:-Fusion of mid portion of upper lip to

maxillary gingival margin 

-Natal teeth 

-Congenital absence of teeth 

-Delayed tooth eruption 

-Defective tooth form (cone-shaped) 

-Enamel hypoplasia 

-Supernumerary teeth

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MACRODONTIA

• Macrodontia refers to teeth that are larger than normal.

• Such teeth may be classified in the same manner as a microdontia.

• True generalized macrodontia:

• The condition in which all teeth are larger than normal

• It is extremely rare

• Associated with pituitary gigantism,.

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Macrodont

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• True macrodontia of a single tooth should not be confused with fusion of tooth, in which, early in odontogenesis, the union of two or more teeth results in a single larger tooth.

• A variant of localized macrodontia is the type that is occasionally seen in cases of hemihypertrophy of the face.

• Here the teeth of the involved side may be considerably larger than those of the unaffected side.

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• Relative generalized macrodontia:

• Somewhat more common • Result of the presence of normal or slightly larger than

normal teeth in small jaws• The disparity in size giving the illusion of macrodontia.• As in microdontia, the importance of heredity must be

considered.

• Macrodontia of single tooth

• Relatively uncommon• Unknown etiology. • The tooth may appear normal in every respect except for

its size.

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• Fraumeni and coworkers stressed that there appear to be some relationship between hemihypertrophy and neoplasm of kidney, liver and adrenal cortex in children.

• Of all reported cases females (63%) are affected more than males (37%).

• There is almost equal involvement of right and left side of face.

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Disturbances in Position of Teeth

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Transposition

• Transposition has been described as an interchange of the position of permanent teeth and is considered to be a relatively rare dental anomaly.

• It was defined by Peck et al. as the positional interchange of two adjacent teeth, particularly of the roots, or the development or eruption of a tooth in a position occupied normally by a non-adjacent tooth.

• The incidence of tooth transposition has been reported to be about 0.4%

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• The maxillary canine is the most commonly involved tooth where in most of the cases it changes its eruptive place with a lateral incisor or a first premolar.

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Translocation

• Translocation refers to an interchange in position of adjacent teeth.

• Because these teeth occupy normal position of other teeth, they are often within the normal curvature of the arch

• Aesthetic and occlusal problems may result.

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Disturbances in Eruption

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Premature Eruption

• Premature eruption of all of the teeth, either deciduous or permanent, may suggest an underlying endocrine dysfunction such as hyperthyroidism.

• These predeciduous teeth have been thought to arise either from an accessory bud of the dental lamina ahead of the deciduous bud or from the bud of an accessory dental lamina.

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Natal teeth

• described my Massler.

• A natal tooth seen at birth may be an aberrant 'tooth' nodule, or it may actually be a deciduous incisor (mandibular central) that has erupted early.

• The predeciduous teeth have been described as hornified epithelial structures without roots, occurring on the gingiva over the crest of the ridge, which may be easily removed.

• Prematurely erupted true deciduous teeth are not to be extracted.

• Premature eruption of permanent teeth is usually sequelae of the premature loss of deciduous teeth.

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Eruption sequestrum

• Starkey and Shafer

• Eruption sequestrum is a tiny irregular spicule of bone overlying the crown of an erupting permanent molar, found just prior to or immediately following the emergence of tips of the cusps through the oral mucosa.

• The spicule directly overlies the central occlusal fossa but is contained within the soft tissue

• As the tooth continues to errupt and the cusps emerge , the fragment of bone completely sequestrates through the mucosa and is lost

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Etiology:

• As the molar tooth erupt through the bone, they will occasionally separate a small osseous fragment from the surrounding contiguous bone .

• This fragment undergoes total resorption prior to eruption.

• if the bone spicule is larger or eruption is fast, complete resorption cannot occur and the eruption squestrum is observed.

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Radiographic features

• it appears as tiny irregular opacity overlying the central occlusal fossa but separated from the tooth itself.

• Clinical significance:

• Sight soreness in the area, probably produced by the compression of the soft tissue over the spicule during eating and just prior to its breaking through the mucosa or by movement of spicule in the crypt during mastication and following eruption through the mucosa.

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Delayed eruption

• Delayed eruption can be due to local or systemic factors.

• For one or a few teeth, surgical exposure and--if needed--orthodontic guidance can bring the tooth into its proper place.

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Impacted teeth

• Impacted teeth are those that have failed to erupt and remain buried in the alveolar bone. Usually, some barrier to eruption will be seen on the X-ray film

• The third molars and maxillary canine are the most frequently impacted teeth, followed by premolars and supernumerary teeth.

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• Cause reosrption of the roots of the adjacent teeth , periodic pain and even trismus particularly when infection occurs around partially impacted teeth.

• Referred pain from impacted teeth

• Occasionally impacted tooth allowed to remain insitu may undergo resrption.

• The process usually begins on the crowns and results in the destruction of enamel and dentin as well a cementum with subsequent replacement by bone

• T/T: SURGICAL REMOVAL

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Unerupted teeth

• A seldom used term for unerupted teeth is embedded teeth.

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Ectopic eruption

• Ectopic eruption is another type of eruption disturbance; this occurs when a tooth cannot complete its eruption because it is blocked by an adjacent tooth or by a misplaced orthodontic band--usually on a first molar tooth.

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Ankylosed deciduous teeth (submerged teeth)

• Submerged teeth are deciduous teeth most commonly mandibular second molars that have undergone a variable degree of root resorption and then have become ankyosed to the bone.

• The process prevents their exfoliation and subsequent replacement by permanent teeth

• After the adjacent permannat teeth have erupted the akylosed teeth apears to have submerged below the level of occlusion.

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• The teeth affected lack mobility .

• Upon pecussion—charecteristic solid sound

• R/F—partial absence of the PDL is seen with areas of apparent blending between the tooth root and the bone..

• The process is basically one of resorption of tooth substance and bony repair with the result that the tooth is locked in bone.

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Post permanent dentition

• A few cases are recorded of persons who have had all their permanent teeth extracted and yet have subsequently erupted several more teeth, particularly after the insertion of a full denture.

• The majority of such cases are the result of delayed eruption of retained or embedded teeth.

• A small number of cases, however, do appear to represent examples of a post permanent or third dentition.

• It probably would be better to classify these as simply multiple supernumerary unerupted teeth.

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Disturbances in Shape of Teeth

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• Gemination / Twinning• Fusion • Peg-shaped teeth• Taurodontism• Dilaceration of crown and roots• Supernumerary cusps and

grooves• Dens in dente • Supernumerary roots• Rhizomegaly• Rhizomicry

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Gemination

• Geminated teeth are anomalies which arise from an attempt at division of single tooth germ by an invagination, with resultant incomplete formation of two teeth.

• The structure is usually one with two completely or incompletely separated crowns that have a single root and root canal.

• It is seen in deciduous as well as permanent dentition

• Appears to exhibit a hereditary tendency.

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• In gemination, there is a shared pulp and root.

• Unlike fusion, the number of teeth is correct; however, the gemination tooth is unusually wide.

• Some writers refer to gemination as 'schizodontism'.

• The term ‘twinning’ has sometimes been used to designate the production of equivalent structures by division resulting in one normal and one supernumerary tooth.

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Fusion

• Fused teeth arise through union of two normally separated tooth germs.

• Some authors refer to fusion as 'syndontism'.

• Depending upon the stage of development of the teeth at the time of the union, fusion may be either complete or incomplete.

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• It has been thought that some physical force or pressure produces contact of the developing teeth and their subsequent fusion.

• If this contact occurs early, at least before calcification begins, the two teeth may be completely united to form a single larger tooth.

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• If the contact of teeth occurs later, when a portion of the tooth crown has completed its formation, there may be union of the roots only.

• The dentin, however, is always confluent in cases of true fusion.

• The tooth may have separate or fused root canals, and the condition is common in the deciduous as well as in the permanent dentition.

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• Grahnen and Granath have reported that fusion of teeth is more common in the deciduous than in the permanent dentition.

• In addition to affecting two normal teeth, fusion may also occur between a normal tooth and a supernumerary tooth such as the mesiodens or the distomolar.

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• This condition can be differentiated from gemination by counting the teeth. The diagnosis can be confirmed if there is a reduction in the number of teeth that are present in the dental arch.

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TAURODONTISM

• The term ‘taurodontism’ was originated by Sir Arthur Keith in 1913.

• Taurodontism literally means 'bull-like teeth'.

• Taurodont teeth are usually molars.

• A peculiar dental anomaly in which the body of the tooth is enlarged at the expense of the roots.

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Shaw further classified taurodont teeth into

Hypotaurodont Mesotaurodont Hypertaurodont

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• Hypertaurodontism being the extreme form in which the bifuracation or trifurcation occurs near the apices of the roots and hypotaurodontism being the mildest form.

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• Clinical Features :

• Taurodontism may affect either the deciduous or permanent dentition (more common).

• The teeth involved are almost invariably molars, (single tooth or several molars in the same quadrant).

• The condition may be unilateral or bilateral or may exhibit any combination of quadrant involvement.

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• Conditions associated with taurodontism- Amelogenesis imperfecta- hypoplastic, type I-E Amelogenesis imperfecta- taurodontism type IV Ectodermal dysplasia Klinefelters Oral-facial-digital, type II Down

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• Roentgenographic Features :

• Involved teeth frequently tend to be rectangular in shape rather than taper toward the roots.

• The pulp chamber is extremely large with a much greater apico-occlusal height than normal.

• In addition, the pulp lacks the usual constriction at the cervical of the tooth and the roots are exceedingly short.

• The bifurcation or trifurcation may be only a few millimeter above the apices of the roots.

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Dilaceration

• The term ‘dilaceration’ refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth.

• The curve or bend may occur anywhere along the length of the tooth depending upon the amount of root formed when the injury occurred.

• The bend can be as much as 90 degrees.

• Such a tooth in the old literature is sometimes called a 'hawk billed tooth'.

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• Dilacerated teeth frequently present difficult problems at the time of extraction if the operator is unaware of the condition.

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Flexion

• Flexion is a deviation or bend restricted just to the root portion of the tooth.

• Usually the bend is less than 90 degrees.

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Dens in dente (Dens invaginatus, dilated composte odontome)

• Dens in dente literally means 'tooth within a tooth'.

• It is in fact a deeply invaginated lingual pit with an important clinical implication: these are very susceptible to caries and they ought to be restored promptly.

• Left unattended, these teeth tend to decay very rapidly.

• Modern literature will often refer this condition as dens invaginatus.

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• It is an uncommon developmental abnormality that primarily affects maxillary lateral incisors.

• The maxillary central incisors are sometimes involved, and the condition is frequently bilateral.

• Oehlers has emphasized that not only are posterior teeth, sometimes affected but also an analogous form of invagination occasionally occurs in the roots of teeth.

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• The invagination may be dialated and disturb the formation of the tooth, resulting in anomalous tooth development termed dialated odontome.

• The first classification of invaginated teeth was published by Hallet (1953).

• Most commonly used classification proposed by Oehlers (1957).

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Oehlers (1957)

• Type I: An enamel lined minor form occurring within the confines of crown not extending beyond the amelocemental junction.

• Type II: Enamel lined form which invades the root but remain confined as a blind sac. It may or may not communicate with the dental pulp.

• Type III: A form which penetrate through the root perforating at the apical area showing the ‘second foramen’ in the apical or periodontal area. There is no immediate communication with the pulp. The invagination may be completely lined by enamel, but frequently cementum will be found lining the invagination.

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• Radicular dens invaginatus is rare and thought to arise secondary to perforation in HERS, with the formation of a strip of enamel that extend along the surface of root.

• This radicular variety of ‘dens in dente’ has been discussed by Bhatt and Dholakia,

• Cementum lined invaginations of root are also reported, but these represent a simple variation of root morphology and should not be included under the term radicular dens invaginatus.

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• Roentgenographically, it is recognized as a pear-shaped invagination of enamel and dentin with a narrow constriction at the opening on the surface of the tooth and closely approximating the pulp in its depth.

• Food debris may become packed in this area with resultant caries and infection of the pulp.

• The more severe forms of ‘dens in dente’ may exhibit an invagination that extends nearly to the apex of the root, and these present a bizarre roentgenogrpahic picture reflecting a severe disturbance in the normal anatomic and morphologic structure of the teeth.

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• This condition, particularly in its mild form, is fairly common.

• The clinical studies of Amos have shown that if the minor invaginations are included, the incidence may be as high as 5 per cent of all patients examined.

• The more severe forms are much less common.

• To prevent caries, pulp infection, and premature loss of the tooth, the condition must be recognized early and the tooth prophylactically restored.

• Fortunately, the defect may be recognized roentgenographically even before the teeth erupt.

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Concrescence

• Concrescence is the joining of tooth roots by cementum.

• It usually involves only two teeth

• It occurs after tooth formation is complete. Usually this condition is 'silent' without clinical significance.

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• The diagnosis can frequently be established by roentgenographic examination.

• The extraction of one may result in the extraction of the other.

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• A related occurrence is hypercementosis. It is a consequence excessive cementum deposition. It occurs in older people often when there are greatly increased or decreased occlusal forces.

(1) The most common one is the Carabelli Cusp which is found on the mesiolingual aspect (on the mesiolingual cusp) of maxillary first molars AND maxillary second deciduous molars.

                                                  

 

(2) 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. These 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.

                   

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Supernumerary cusps

• extra cusps are occasionally found on teeth.

1. Carabelli Cusp

2. talon cusp

3. 'dens evaginatus'

4. 'Uto-Aztecan

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Carabelli Cusp

-This occlusal landmark can appear with varying degrees of intensity either as a cusp or pit. These conditions are known collectively as the Carabelli trait.

-it is frequently a site of early dental caries. It is a heritable trait most commonly seen in European populations.

- The Carabelli trait is best understood as a variation, not an anomaly.

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Talon cusp

• A talon cusp is an extra cusp that resembles an eagle's talon (a talon is the claw of a bird of prey).

• An anomalous structure resembling an eagle’s talon, projects lingually from the cingulum areas of a maxillary or mandibular permanent incisor.

• This cusp blends smoothly with the tooth except that there is a deep developmental groove where the cusp blends with the sloping lingual tooth surface.

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• These can interfere with occlusion; however, grinding them down is a hazardous endeavor.

• It is composed of normal enamel and dentin and contains a horn of pulp tissue.

• prominent pulp horn is very susceptible to exposure in the younger patient.

• Mellor and Ripa have recommended prophylactically restoring the groove to prevent caries.

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• It has been reported by Gardner and Girgis that it appears to be more prevalent in persons with the Rubinstein – Taybi syndrome :

- developmental retardation, - broad thumbs and great toes, - characteristic facial features, - delayed or incomplete descent of testes

in males, and - stature, head circumference, and bone

age, below the 50thpercentile

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Dens evaginitus

• Occlusal tuberculated premolar, Leong’s premolar, Evaginated odontome, Occlusal enamel pearl.

• Very rarely, a similar projection of enamel can occur on the occlusal surface of the premolar teeth.

• It forms a tubercle called a 'dens evaginatus'.

• appears clinically as an accessory cusp or a globule of enamel on the occlusal surface between the buccal and lingual cusps of premolars

• May be unilateral or bilateral

• It has also been reported to occur rarely on molars, cuspids, and incisors.

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• Dens evaginitus can also contain a pulp horn as does the talon cusp mentioned earlier. Fortunately, these conditions are infrequent

• It has been thought to develop only in people of Mongoloid ancestry : Chinese, Japanese, Filipions, Eskimos, and American Indians.

• This ‘extra’ cusp may contribute to incomplete eruption, displacement of teeth and pulp exposure with subsequent infection following occlusal wear or fracture.

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• One other variation of the upper first premolar is the 'Uto-Aztecan' upper premolar.

• It is a bulge on the buccal cusp that is only found in Native American Indians, with highest frequencies of occurence in Arizona.

• The name is not a dental term; it comes from a regional linguistic division of Native American Indian language groups.

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Shovel shaped incisors

• Shovel shaped incisors display enhanced marginal ridges and present with a distinctive shovel-shaped appearance on the lingual aspect.

• They appear frequently in many persons of Asian origin, including many Native American Indians. They are especially prominent in Eskimo/Inuit who are descendants of Siberians about 4,000 years ago.

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Enamel pearls

• Enamel pearls (enamelomas) are small nodules of enamel found on the root of the tooth close to or at the cemento-enamel junction.

• They are found most often at the bifurcation or trifurcation of molars.

• They do appear radiographically.

• While they can be a problem in periodontal disease, they should usually be left alone. Their attempted removal can do more harm than good.

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Hutchinson's incisors

• Hutchinson's incisors or mulberry molars are developmental anomalies that result from congenital syphilis. Clinically, the incisor teeth are, on occasion called 'screwdriver teeth' due to their distinctive shape.

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Winged incisors

• Winged incisors are not a disturbance of development, but rather a special case of rotation of the upper central incisors. It is usually described as a distinctive bilateral rotation to the mesial which is particularly common amongst Native American Indians.

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Root variations

• Incidentally, most root variation is in the distal third of the root. Sometimes roots can be blunted or shortened. It tends to occur without apparent cause.

• On occasion, root resorption and root blunting can be unfortunate consequence of orthodontic treatment with fixed appliances.

• A few patients are very susceptible to this condition, and the practitioner's heart sinks when it is found--without warning--on the post treatment X-ray films.

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• Below is a brief discussion of extra or fused roots.

(a.) Upper first premolars usually have two roots; however, one root is occasionally found in these teeth. More rarely there are three roots.

(b.) Lower permanent canines on occasion have a bifurcation near the apex resulting in two short roots. A question about this condition has appeared frequently on Part I National Boards for dental students.

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(c.) Sometimes lower first permanent molars have three roots. It is the mesial molar root that is bifurcated. Clinical articles often consider it an anomaly. It is just a variation. Three rooted lower first molars are found in greater frequency amongst North American Indians with origins in Asia.

(d.) In upper third molars, and on occasion with fused roots, second molars, the roots can be fused together. This is a variation, not a pathological condition.

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REFERENCES

• © J Can Dent Assoc 1999; 65:612-6 Supernumerary Teeth -An Overview of Classification, Diagnosis and Management.

• British Dental Journal 204, 598 (2008) Incisor transposition . A. A. Sholapurkar

• Oral Diagnosis, Oral Medicine, and Treatment Planning (page 641)

•  By Steven L. Bricker, Robert P. Langlais, Craig S Miller

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DEVELOPMENTAL DISTURBANCES IN STRUCTURE OF TEETH

AMELOGENESIS IMPERFECTA

• Hereditary enamel dysplasia, hereditary brown enamel, hereditary brown opalescent teeth

• A structural defect of the tooth enamel with complex inheritance pattern

• Depending on the clinical presentation & likely stage of enamel formation that is primarily affected, it may be

Hypoplastic Hypocalcified Hypomaturative

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• Factors associated with enamel defects

• Neurologic disorders• Cerebral palsy • Mental retardation

• Metabolic disorders

• Cardiac disease

• Celiac disease

• Hypocalcemia

• Hypothyroidism

• Renal disease

• Maternal diabetes

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• Hypoparathyroidism

• Infection• Cytomegalo virus• Measles• Rubella• Pneumonia• Tetanus• Syphilis

• Chemicals• Anti-neoplastic chemotherapy• Fluoride• Lead• Tetracycline• Thalidomide• Vitamin D

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• Each main clinical group of AI may be further divided into several subgroups depending on the mode of inheritance, as well as the clinical appearance of the defective enamel.

• In some cases, overlapping clinical features may make distinction difficult.

• The prevalence range from 1in 718 to 1 in 14,000, depending on the population studied.

• Hypoplastic AI: 60-73 per cent of all cases

• Hypomaturation AI : 20-40 per cent

• Hypocalcification AI : 7 per cent.

• Disorders of the enamel epithelium also can cause alterations in the eruption mechanism, resulting in the anterior open bite.

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• Classification of Amelogeneis imperfecta according to Witkop (1989) :

• Type I : Hypoplastic• IA : Hypoplastic, pitted autosomal dominant • IB : Hypoplastic, local autosomal dominant • IC : Hypoplastic, local autosomal recessive • ID : Hypoplastic, smooth, autosomal dominant • IE : Hypoplastic, smooth x-linked dominant • IF : Hypoplastic, rough autosomal dominant • IG : Enamel agenesis , autosomal recessive.

• Type II Hypomaturation : • IIA : Hypomaturation, pigmented,AR• IIB : Hypomaturation , X- lined recessive • IIC : Snow- capped teeth, AD.

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• Type III Hypocalciffied :

• IIIA : Autosomal dominant • IIIB : Autosomal recessive.

• Type IV Hypomaturation – hypoplastic with taurodontism :

• IVA : Hypomaturation- hypoplastic with taurodontism, AD

• IVB : Hypoplastic – hypomaturation with taurodontism, AD

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Type Clinical Appearance

Enamel Thickness Radiographic Appearance

Inheritance

Hypoplastic (Type I)

Crowns size varies from small to normal, small teeth may lack proxmial contacts, color varies from normal to opaque white – yellow brown

Varies from thin and smooth to normal thickness with grooves, furrows and/or pits

Enamel has normal to slightly reduced contrast/ thin

Autosomal dominant, recessive, or X-linked

Hypomaturation(Type II)

Varies from creamy opaque to marked yellow/brown, surface of teeth soft and rough, dental sensitivity and open bite common

Normal thickness with enamel that often chips and abrades easily

Enamel has contrast similar to or > than dentin, unerupted crowns have normal morphology

Autosomal dominant, recessive, or X-linked

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Type Clinical Appearance Enamel Thickness Radiographic Appearance

Inheritance

Hypocalcified(Type III)

Opaque white to yellow-brown, soft rough enamel surface, dental sensitivity and open bite common, heavy calculus formation common

Normal thickness with enamel that often chips and abrades easily

Enamel has contrast similar to or < dentin, unerupted crowns have normal morphology

Autosomal dominant, recessive

Hypomaturation/ Hypoplasia/Taurodontism(Type IV)

White/Yellow- Brown mottled, teeth can appear small and lack proximal contact

Reduced, hypomineralized areas and pits

Enamel contrast normal to slightly > dentin, large pulp chambers

Autosomal dominant

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• Molecular genetic studies have shown that the aetiology of AI is related to the alteration of genes involved in the process of formation and maturation of the enamel.

• Although the genetic origin of the autosomal forms is less understood, analysis of X-linked AI has shown the defective gene for this specific AI type to be closely linked to the locus DXS85 at Xp22.

• Interestingly, this also has been identified as the general location of the human gene for amelogenin, the principal protein in developing

enamel.

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• Histologic Features :

• There is a disturbance in the differentiation or viability of ameloblasts in the hypoplastic type.

• In the hypocalcification types there are defects of matrix structure and of mineral deposition.

• In the hypomaturation types there are alterations in enamel rod and rod sheath structures.

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Dentinogenesis Imperfecta

• This is an autosomal dominant condition affecting both deciduous and permanent teeth.

• Affected teeth are gray to yellowish-brown and have broad crowns with constriction of the cervical area resulting in a 'tulip' shape.

• Radiographically, the teeth appear solid, lacking pulp chambers and root canals.

• Enamel is easily broken leading to exposure of dentin that undergoes accelerated attrition

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• The gene maps to chromosome #4.

• It encodes a protein called dentin sialophosphoprotein (DSPP).

• This protein constitutes about 50% of the noncollagenous component of dentin matrix.

• Dentin defect associated with osteogenesis imperfecta was earliar listed as dentinogenesis imperfecta type I (Shields classification).

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• Extensive studies have proven that dentinogenesis imperfecta is clearly a disorder distinct from osteogenesis imperfecta hence the following revised classification is proposed.

• Dentinogenesis imperfecta 1: Dentinogenesis imperfecta without osteogenesis imperfecta (opalescent dentin) this corresponds to dentinogenesis imperfect, tvpe II of Shields chssification.

• Dentinoenesis Imperfecta 2: Brandywine tvpe dentinogenesis imperfecta: this corresponds to dentinogenesis imperfecta type III of Shields classification.

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• Dentinogenesis imperfecta 2 is more rare and paradoxically characterized bv too little rather than too much dentin resulting in 'shell teeth’.

• Dentinogenesis imperfecta 2 may be an allelic variant of dentinogenesis impertecta 1 (a different mutation in the same gene), as both genes map to the same region on chromosome #4.

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DENTINOGENESIS IMPERFECTA :1

• Opalescent dentin, dentinogenesis impertecta without osteogenesis imperfecta, Opalescent tecth without osteogenesis imperfecta, , Shields type II

• Dentinogenesis impertecra 1 is caused by mutation in the DSPP gene (gene map locus 4q21.3) encoding dentin phosphoprotein and dentin sialoprotein.

• Dentinogenesis impertecta is an entity clearly distinct from osteogenesis imperfecta with opalescent teeth, and affects only the teeth.

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• There is no increased frequency of bone fractures in this disorder.

• The frequency may be 1 in 6,000-8,000 children.

• Witkop and Rao ( 1971) preferred the term opalescent dentin for this condition as an isolated trait, reserving dentinogenesis miperfecta for the trait when it is combined with osteogenesis imperfecta.

• The teeth are blue-gray or amber brown and opalescent.

• On dental radiographs the teeth have bulbous crowns, roots that are narrower than normal, and pulp chamber and root canals that are smaller than normal or completely obliterated.

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• The enamel may split readily from the dentin when subjected to occlusal stress.

• Saukri et al. (1976) noted an increase in glycosaminoglycans in EDTA soluble dentin in the teeth from patients with this disorder as compared to controls, and less glycosaminoglycans in EDTA insoluble dentin residue.

• A deficiency of dentin sialophosphoprotein had been suggested as a causative factor in dentinogenesis imperfecta.

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Dentinogenesis imperfecta: 2

• Shields type III, Brandywiine type dentinogenesis imperfecta

• This disorder was found in the Brandywine triracial isolate in southern Maryland.

• The crowns of the deciduous and permanent teeth wear rapidly after eruption and multiple pulp exposures may occur.

• The dentin is amber color and smooth.

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• Radiographs of the deciduous dentition show very large pulp chambers and root canals, at least during the first few years.

• They may become reduced in size with age.

• The permanent teeth have pulpal spaces that are either smaller than normal or completely obliterated.

• Patients with Shields type III, or the Brandywinc type, do not have stigmata of osteogenesis imperfecta

• This disorder may be a separate mutation from dentinogenesis imperfccta 1.

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• Shields el al. (1973) stated that multiple pulp exposures and markedly enlarged pulp chambers in the deciduous teeth do not occur in DGI-1.

• Recent studies are consistent with the hypothesis that DGI-1 and DGI-2 are allelic or the result of mutations in two tightly linked genes.

• MacDougall el al. (1999)) stated that the manifestations of DGI-2 can differ from those of DGI-1 by the presence of multiple pulp exposures, normal nonmineralized pulp chambers and canals, and a general appearance of 'shell teeth'.

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• They illustrated the amber discoloration of the teeth, attrition, and fractured enamel, as well as the classic 'shell teeth' appearance on radiographs.

• Histologic Features.

• The appearance of the enamel is essentially normal except for its peculiar shade, which is actually a manifestation of the dentinal disturbance.

• The dentin, on the other hand, is composed of irregular tubules, with large areas of uncalcified matrix.

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• The tubules tend to be large in diameter and thus less numerous than normal in a given volume of dentin.

• In some areas there may be complete absence of tubules.

• Cellular inclusions,probably odontoblasts, in the dentin are not uncommon

• The pulp chamber is usually almost obliterated by the continued deposition of dentin.

• The odontoblasts have only limited ability to form well- organized dentinal matrix, and they appear to degenerate readily,becoming entrapped in this matrix.

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Obliterated pulp chambers

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Normal dentin tubules

Dentinal tubules in DI are disoriented irregular & widely spaced

Obliterated pulp

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• Chemical and physical features:

• Cemical analysis explains many of the abnormal features of the teeth of dentinogenesis imperfecta-1.

• Their water content is greatly increased, as much as 60% above normal, while the inorganic content is less than that of normal dentin.

• The density, X ray absorption, and hardness of the dentin are also low.

• The microhardness of the dentin closely approximates that of cementum, thus explaining the rapid attrition of affected teeth.

• There is no significant information available on teeth in typeIII (DGI-2).

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• Treatment:

• Directed primarily towards preventing the loss of enamel and subsequent loss of dentin through attrition.

• Cast metal crowns on the posterior teeth and jacket crowns on the anterior teeth have been used.

• Fillings are not usually permanent because of the softness of the dentin.

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Dentin Dysplasia (Rootless teeth)

• A rare disturbance of dentin formation.

• Characterized by normal enamel but atypical dentin formation with abnormal pulpal morphology.

• Previously it was thought to be a single disease. entity

• Shields and his associates separarted it in to Type I (Dentin dysplasia) Type II (anomalous dysplasia of dentin).

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• Witkop referred these conditions as radicular dentin dysplasia (type I) and coronal dentin dysplasia (typeII)

• Type I is more common.

• The first description of the disease was given by Ballschmiede.

• He reported the spontaneous exfoliation of multiple teeth in 7 children of one family in 1920 and called this phenomenon “rootless teeth”.

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• The first concise description of the disease was published in 1939 by Rushton, who was also the first to designate it as 'dentin dysplasia. '

• Dentin dysplasia, both type 1 and type II, appears to be a hereditary disease, transmitted as an autosomal dominant characteristic.

• Nothing is known of the mutation rate, but it must be extremely low.

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• Conditions associated with dentin dysplasia

• Calcinosis universalis

• Rheumatoid arthritis

• Vitaminosis D

• Sclerotic bone and skeletal anomalies

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• Type I (radicular)

• Both dentitions are affected

• The teeth appear clinically normal in morphologic appearance and color.

• On occasion, there may be a slight amber translucency.

• The teeth characteristically exhibit extreme mobility and are commonly exfoliated prematurely or after only minor trauma as a result of their abnormally short roots.

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• Type II (coronal)

• Both dentitions are affected.

• The deciduous teeth have the same yellow, brown, or bluish-gray opalascent appearance as seen in dentinogenesis imperfecta.

• The clinical| appearance of the permanent dentition is normal.

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• Roentgenographic Features• Type I (radicular)

• In both dentitions, the roots are short, blunt, conical, or similarly malformed .

• In the deciduous teeth, the pulp chambers and root canals are usually completely obliterated, while in the permanent dentition, a crescent-shaped pulpal remnant may still be seen in the pulp chamber.

• The obliteration in the permanent teeth commonly occurs preeruptively.

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• Type II (coronal) • The pulp chambers of the deciduous teeth become obliterated as in

type I and in dentinogenesis imperfecta.

• The permanent teeth, however, exhibit an abnormally large pulp chamber in the coronal portion of the tooth, often described as 'thistle-tube' in shape

• Within such areas radiopaque foci resembling pulp stones may be found.

• Periapical radiolucencies do not occur unless for an obvious reason.

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Rootless teeth

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• Histologic Features:• Type I (radicular).

• A portion of the coronal dentin is usually normal.

• Apical to this may be areas of tubular dentin, but most of that which obliterates the pulp is calcified tubular dentin, osteodentin, and fused denticles.

• Normal dentinal tubule formation appears to have been blocked so that new dentin forms around obstacles and takes on the characteristic appearance described as 'lava flowing around boulders'.

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• Electron microscope studies by Sauk and his coworkers have suggested that this pattern of 'cascades of dentin' results from repetitive attempts to form root structure.

• Interestingly, the dentin itself is histologically normal but is simply disoriented.

• Type II (coronal)

• The deciduous teeth exhibit amorphous and atubular dentin in the radicular portion, while coronal dentin is relatively normal.

• The permanent teeth also show relatively normal coronal dentin, but the pulp has multiple pulp stones or denticles.

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Regional odontodysplasia

• Odontodysplasia, odontogenic dysplasia, odontogenesis imperfecta, ghost teeth

• This is an unusual dental anomaly in which one or several teeth in a localized area are affected in an unusual manner.

• Apparently the maxillary teeth are involved more frequently than the mandibular

• The most frequently affected teeth being the maxillary permanent central incisor, lateral incisor, and cuspid.

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Conditions associated:

• Ectodermal dysplasia

• Epidermal nevi

• Hypophosphatasia

• Neurofibromatosis

• Rh incompatibility

• Vascular nevi

• Hydrocephalus

• Ipsilateral facial hyperplasia

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• The etiology of this disease is unknown.

• Suggested etiology:1. A somatic mutation or 2. A latent virus residing in the odontogenic epithelium, which

subsequently becomes active during the development of the tooth.

• Walton and his coworkers observed that in three cases of regional odontodysplasia that they reported, all three patients had vascular nevi of the overlying facial skin as infants.

• These findings suggested to them that local vascular defects are involved in the pathogenesis of the condition.

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• The teeth affected by odontodysplasia exhibit either a delay or a total failure in eruption.

• Their shape is markedly altered, being generally very irregular in appearance, often with evidence of defective mineralization.

• The radiographs are uniquely characteristic, showing a marked reduction in radiodensity so that the teeth assume a 'ghost’ appearance.

• Both the enamel and dentin appear very thin and the pulp chamber is exceedingly large.

• The enamel layer often is not evident.

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• Histologic Features

• The most characteristic features of the disease are The marked reduction in the amount of dentin The widening of the pre-dentin layer

The presence of large areas of inter-globular dentin An irregular tubular pattern of dentin.

• Characteristically, the reduced enamel epithelium around uneruptcd teeth shows many irregular calcified bodies.

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• Indistinguishable DEJ, Ghost teeth appearance

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Hypoplastic enamel with normal prismatic structure

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Large area of interglobular dentin

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Dentin hypocalcification

• Normal dentin is calcified by deposition of calcium salts in the organic matrix in the form of globules, which increase in size by further peripheral deposition of salts until all the globules are finally united into a homogeneous structure.

• In dentinal hypocalcification there is failure of union of many of these globules, leaving interglobular areas of uncalcificd matrix.

• This globular dentin is easily detected in both ground sections and decalcified histologic sections of teeth, but there is no alteration in the clinical appearance.

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• Many clinicians believe that they can detect areas of globular dentin by the softness of the dental structure.

• Although this remains to be proved, it is logical that hypocalcified dentin would be softer than well calcified dentin.

• Any factor which interferes with normal calcification, such as parathyroid deficiency or rickets, could produce hypocalcification.

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Human genes for dental anomalies

• Amelogenesis imperfecta:

• Aldred and Crawford (1995) proposed an classification based upon molecular genetic findings together with the resulting biochemical changes and the mode of inheritance as the primary discriminator.

• Amelogenins is a major group of enamel proteins.

• In humans two amelogenin genes, AMGX and AMGY, have been cloned and mapped to Xp22.1 – 22.3 and Yq11 respectively.

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• The mutation of AMGX has been implicated in X linked amelogenesis imperfecta.

• Although autosomally inherited AI is more common, more genetic studies are performed on X linked type.

• Mac Dougall mapped the gene of ameloblastin (amelin) at 4q22, thought to be responsible for autosomal dominant hypoplastic AI.

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Dentinogenesis imperfecta:

• It is a autosomal dominant disorder.

• Patients with DI-I have mutations in either COL1-A1 or COL1-A2 genes which encode the subunits of collagen type I.

• The production of defective procollagen type I result in pathogenesis of DI.

• Several studies have localized gene responsible for DI-II at 4q13-21.

• Recently DMP-1 (dentin matrix protein) gene located on chromosome 4 has been suggested to be a strong candidate for DI-II.

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A human MSX-1 homeodomain gene

• Vastardis et al (1996) demonstrated that mutation in MSX-1 causes familial tooth agenesis.

• It was located on 4p by genetic linkage analysis.

• They proposed that missense mutation in MSX-1 affects interaction of MSX1 with other proteins and DNA and cause familial tooth agenesis via a dominant negative mechanism.

• They also suggested that MSX1 functions are critical for normal development of specific human teeth.

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Certain conditions associated with tooth anomalies:

• Mucopolysaccharidosis- Thin enamel with pointed cusp• Lipoid proteinosis- Enamel hypoplasia• Deficiency of vit.A & C- Enamel hypoplasia• Hypoparathyroidism- Pitting enamel hypoplasia• Hyperparathyroidism- Pulp stones• Hypophosphatasia- Reduced cementum and dentin, large pulp

chambers enamel hypoplasia• Vitamin-D resistant rickets- Large pulp chambers (reaching DEJ),

hypocalcified dentin, abnormal cementum.• Tuberous sclerosis- Pitting of enamel

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• Dystrophic calcification- Pulp stones• Osteogenesis imperfecta- Hypoplastic dentin• Downs syndrome- Enamel hypoplasia• Osteopetrosis- Teeth hypoplasia, prone to dental caries• Erythroblastosis foetalis- Enamel hypoplasia• Chondroectodermal dysplasia- Enamel hypoplasia• Epidermolysis bullosa dystrophica- Hypoplasia of teeth with

crown denuded of enamel

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• Junctional epidermolysis bullosa-Disturbance in enamel and dentin formation in primary and secondary teeth

• Ehlers danlos syndrome- Flattening of DEJ , enamel hypoplasia, pulp stones

• Focal dermal hypoplasia syndrome- Enamel hypoplasia

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Conclusion

• As new genes and mutations associated with hereditary dental diseases are discovered, it will be possible to describe the classification of these diseases not only on a clinical level but also at molecular level .

• Such expanding information could lead to the development of future sensitive diagnostic tools.

• “Order is never observed; it is disorder that attracts attention because it is awkward and intrusive.”

Eliphas Levi

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References

1. Oral & maxillofacial pathology 2nd edition Neville.

2. Oral pathology 5th edition. Rajendran & Sivapathasundaram

3. Thoma’s oral pathology 6th edition.

4. Human genes for dental anomalies. Oral diseases 1997 (3) 223-8

5. Dens invaginatus. Int. endol. Jour 1997(30) 79-90.

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