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Dentinogenesis Imperfecta

 Dentinogenesis imperfecta (DI) has an autosomal-dominant pattern of inheritance. Genetic disturbances in dentin formation lead to altered morphology of  dentin formation in the absence of a systemic involvement. Abnormalities of dentin include dentinogenesis imperfecta and dentin dysplasia.   It typically affects the dentin of both primary and permanent dentitions. Because of the clinical discoloration of teeth, this condition has also been known as (hereditary) opalescent dentin

 Teeth with dentinogenesis imperfecta appear blue-gray or amber brown and are opalescent. There are three identified types (I, II, III). Dentinogenesis imperfecta can be nonsyndromic or associated with osteogenesis imperfecta.Type I is associated with osteogenesis imperfecta. Nonsyndromic dentinogenesis imperfecta is caused by mutations in the DSPP (dentin sialophosphoprotein) gene, which encodes dentin sialoprotein, a non-collagenous protein of dentin.  In type II, patients have only dentin abnormalities and no bone disease. In type III, or the Brandywine 383type (discovered in a triracial population in Brandywine, Maryland), only dental defects occur. This type is similar to type II, but has some clinical and radiographic variations. Features of type III that are not seen in types I and II include multiple pulp exposures, periapical radiolucencies, and a variable radiographic appearance

Dentinogenesis imperfecta type I (syndromal dentinogenesis imperfecta) is caused by mutations in the genes that encode collagen type I,  which is associated with osteogenesis imperfecta: by mutations in the type I collagen genes COL1A1 or COL1A2. Osteogenesis imperfecta is a heterogeneous group of heritable connective tissue disorders, caused by abnormal type I collagen synthesis. Characteristic features include increased bone fragility, bone deformities, joint hyperextensibility, blue sclerae, hearing loss, and dentinogenesis imperfecta.

Dentinogenesis imperfecta types II and III, on the other hand, have been shown to be related to mutations in a gene known as dentin sialophosphoprotein that encodes noncollagen proteins of dentin.

Dentinogenesis imperfecta. A and B, Brothers.

Radiographic Features:

Clinical diagnosis:

  • In both dentitions, the teeth exhibit an unusual translucent, opalescent appearance, with color variation from yellow-brown to gray.
  • The entire crown appears discolored because of the abnormal underlying dentin. Although the enamel is structurally and chemically normal, it fractures easily, resulting in rapid wear.
  • The enamel fracturing is believed to be due to the poor support provided by abnormal dentin, and possibly in part to the absence of the microscopic scalloping normally seen between dentin and enamel, which is believed to help mechanically lock the two hard tissues together.
  • Overall tooth morphology is unusual for its excessive constriction at the cementoenamel junction, giving the crowns a tulip or bell shape.
  • Roots are shortened and blunted.
  • The teeth do not exhibit any greater susceptibility to caries, and they may in fact show some resistance because of the rapid wear and absence of interdental contacts.

Radiographic Features:

  •  Types I and II exhibit identical changes. Opacification of dental pulps occurs as the result of continued deposition of abnormal dentin.
  •  The short roots and the bell-shaped crowns are also obvious on radiographic examination.
  •  In type III, the dentin appears thin and the pulp chambers and root canals extremely large, giving the appearance of thin dentin shells, hence the previous designation of shell teeth.

 

Treatment is directed toward protecting tooth tissue from wear and tear, thereby improving the esthetic appearance of the teeth. Generally, fitting with full crowns at an early age is the treatment of choice. Despite the qualitatively poor dentin, support for the crowns is adequate. These teeth should not be used as abutments because the roots are prone to fracture under stress.

a. A 10-year-old boy presenting with dentinogenesis imperfecta (DGI) type II in the mixed dentition. In the permanent dentition, the mandibular incisors are most severely affected. B.  Radiographic findings of DGI in the same boy at 6 years of age. Marked cervical constriction, varying degree of pulpal obliteration, and short roots are visible

Clinical phenotype of moderate dentinogenesis imperfecta (formerly DGI Shield type II) in Primary teeth of 6-year-old boy (a–c) and permanent teeth at 8 years old (d–f), primary teeth show brown opalescent discoloration, severe attrition, complete pulp obliteration of erupted teeth, bulbous crown, short root, periapical radiolucency without carie. Primary teeth are more severely affected than permanent teeth.

Dentin Dysplasia

Dentin dysplasia (DD) is another hereditary developmental disorder of dentin formation, which shows loss of organization of dentin during development. It is not associated with systemic involvement or DI. There are two types of DD. Type I, or radicular, DD teeth show dentin formation defects in the root that result in short roots while their crowns appear normal. Therefore, affected teeth exhibit severe mobility and are susceptible to premature exfoliation and root fracture. The pulp chambers are severely obliterated by dysplastic dentin or pulp stones, resulting in a crescent-shaped pulp. Periapical inflammatory lesions may be accompanied in the absence of dental caries. Type II, or coronal, DD teeth have normal root length and show many features that resemble DI. Affected deciduous teeth show bulbous crowns, cervical constriction, thin roots, and early obliteration of the pulp. On the other hand, affected permanent teeth show enlarged and apically extended pulp chambers.

Type I, or radicular dentine, dysplasia:

 Affects both dentitions.

Morphology and colour of the crown of the teeth are normal.

Hypermobility of teeth: The roots are seen on radiographs as short and with pointed ends and conical apical constrictions.

Aberrant growth of dentine leads to reduced pulp space in permanent teeth and total pulpal obliteration in the primary dentition.

Teeth are lost generally due to trauma, which will easily induce exfoliation because of the roots shape and short length.

There is a delayed eruption.

Opacity of the incisional margins is present.

Periapical radiolucencies are often seen in non-carious teeth.

Clinical Features:  the crowns in dentin dysplasia type I appear to be normal in color and shape. Premature tooth loss may occur because of short roots or periapical inflammatory lesions. Teeth show greater resistance to caries compared with normal teeth.

Radiographically, in dentin dysplasia type I, roots appear extremely short and pulps are almost completely obliterated. Residual fragments of pulp tissue appear typically as horizontal lucencies (chevrons). Periapical lucencies are typically seen; they represent chronic abscesses, granulomas, or cysts. In dentin dysplasia type II, deciduous teeth are similar in radiographic appearance to those in type I, but permanent teeth exhibit enlarged pulp chambers that have been described as thistle tube in appearance.

Clinical phenotype of radicular dentinal dysplasia (formerly DD Shield type I): teeth show normal colour (a) and shape but roots are severely shortened with conical apex and molar are taurodont (b) (arrow).

Dentin dysplasia Type 1 . Note obliterated pulps, short roots, and periapical lesions

Type II:

Primary teeth are amber and translucent, resembling DGI-II.

Pulp chambers are obliterated by abnormal dentine.

The permanent teeth have a normal coronal morphologic character and colour and seem either unaffected or show mild radiographic abnormalities.

Permanent teeth have ‘thistle tube’–shaped pulp chambers and multiple pulpal calcifications.

The clinical features characteristic of various forms of DGI and DD can be seen in different individuals of the same kindred.

Clinical phenotype of mild dentinogenesis imperfecta (formerly DD Shield type II) in primary teeth of a 4-year-old girl (a–c) and permanent teeth at 10 years old (d–f), primary teeth show amber opalescent discoloration, attrition of first molar, partial to complete pulp obliteration of erupted teeth, bulbous crown and short root. Permanent teeth show normal colour without attrition. (g) Panoramic radiograph of their mother showing typical ‘thistle pulp’ aspect, constriction at enamel cement junction (arrow), short root and periapical radiolucency without caries (*).

Dentin dysplasia type II. Note horizontal ribbons (chevrons) of dental pulp.

Management/Oral Health

 Patients with DD-I have mobile teeth due to very short roots and as a result tend to lose teeth early in the primary and permanent dentition. Until growth is complete, the treatment of choice for the replacement of missing teeth is dentures; thereafter, implants should be considered.

 Dentine dysplasia. (A) DD type I with normal appearance of the teeth and short roots visible on X-ray. (B) DD type II in a boy. The dental phenotype in the primary dentition is similar to dentinogenesis imperfecta type II. (C) DD type II is the mother of the patient in (B). The clinical appearance of teeth is subnormal. (D) Another appearance of dentine dysplasia

Dentinogenesis imperfecta of dentinal dysplasia type 2 presentation. The pulp chambers are rounded, tall and wide in the developing dentition. The classical ‘thistle-shaped’ pulp appearance is seen in the lower canine and premolars.

Shield classification of isolated dentin diseases

Proposed classification of isolated dentin diseases

 

 

Dentin dysplasia type I

Radicular dentin dysplasia

 

Dentinogenesis imperfecta

Dentin dysplasia type II

 Mild form

Dentinogenesis imperfecta type II

 Moderate form

Dentinogenesis imperfecta type III

 Severe form


Dentinogenesis imperfecta and dentin dysplasia: revision of the classification.

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