What Is Dentin Dysplasia Type II

Overview

Dentin dysplasia type II, also known as coronal dentin dysplasia, is a rare genetic disorder that affects one of the teeth’s tissues, the dentin, resulting in discolouration of the teeth.¹ Although those affected by coronal dentin dysplasia have normal enamel (the outermost tissue of the tooth), these individuals exhibit teeth that are discoloured, either in yellow, brown, amber or even grey/blue tint.¹ It affects the primary (deciduous) teeth or baby teeth.¹ Since this disease can present similarly to other conditions, let’s understand more what can cause dentin dysplasia type II and how it differs from other disorders such as dentin dysplasia type I and dentinogenesis imperfect.

Causes

Dentin dysplasia type II is a genetic disorder caused by the mutation of the Dentin Sialophosphoprotein (DSPP) gene in chromosome 4.² This condition is inherited in an autosomal dominant manner, meaning that regardless of gender, if an individual inherits the defective gene from one or both of their biological parents, they will develop this disorder.¹

The crowns of teeth are composed of three main tissues: enamel, the outermost layer of mineralised tissue; dentin, an intermediate layer that is less mineralised than enamel, and that has small tubules that connect it to the pulp; and inside it, there’s the pulp, a soft tissue composed of nerves and blood vessels, which is what gives vitality and sensibility to the teeth.⁴

Similarly to dentinogenesis imperfecta, coronal dentin dysplasia is related to mutations of the DSPP gene, which is responsible for producing a protein called dentin sialophosphoprotein. This is a precursor protein produced by a group of cells called odontoblasts that are responsible for producing dentin - one of the hard, mineralised tissues of the tooth.³ 

Dentin sialophosphoprotein is broken down into three other proteins as the tooth is maturing and developing: dentin sialoprotein (DSP), dentin glycoprotein (DGP), and dentin phosphoprotein (DPP); these proteins regulate how and when mineralisation of the dentin occurs, and if they are defective, mineralisation can be partial or abnormal.³

Mutations of the DSPP gene

They can be categorised into two classes:¹

• Class I: mutation of the first part of the DSPP gene
  • Reduces the secretion of dentin sialophosphoprotein and makes it toxic to the cells around it
  • Results in dentinogenesis imperfecta type II or dentinogenesis imperfecta type III¹
• Class II: mutation of the second half of the DSPP gene
  • This causes it to become more hydrophobic (that is, less likely to mix into water) and also toxic to the cells 
  • Results in dentinogenesis imperfecta types II or III, but it can also cause dentin dysplasia type II. it is still unknown why it can cause multiple diseases (all are similar in presentation with different severities)¹

Signs and symptoms

In coronal dentin dysplasia, only the primary (deciduous) teeth are affected; if the secondary (permanent) teeth are affected, the diagnosis is changed to dentinogenesis imperfecta type II.¹

Common signs and symptoms are:

Discoloured baby teeth

They can either be yellow, grey/amber, brown, or blue; teeth can also be opalescent (milkier in colour).¹

X-ray findings

In an X-ray, the roots of both deciduous and permanent teeth appear normal (unlike in dentin dysplasia type I). However, the permanent teeth have enlarged pulp chambers (often flame-shaped or  “thistle tube” shaped) or calcification of the pulp tissue.¹

Pulp stones

Due to the calcification (pulp stones), the pulp chamber in permanent teeth can be partially obliterated.¹

Prone to wear

Teeth are usually weaker and more prone to wear, with visible signs of abrasion in some cases.¹

Diagnosis

Diagnosis is made through a combination of clinical evaluation of signs and symptoms, X-ray exams and family history.¹ 

Differential diagnosis

Other possible differential diagnoses include:⁵

Dentin dysplasia type I

Affects both primary and secondary teeth causing abnormalities of the pulp; however, dentin dysplasia type I doesn’t often cause discoloration of the teeth, and it is characterised by abnormalities of the roots (short, blunt and malformed roots), while dentin dysplasia type II does not appear to cause root abnormalities.⁵

Dentinogenesis imperfecta (DGI)

It affects both permanent and deciduous teeth and can cause discolouration of the teeth.⁵ It can be further divided into three types:

• Dentinogenesis imperfecta type I (DGI I): this is a type of osteogenesis imperfecta with associated dentinogenesis imperfecta, meaning that it affects both teeth and bone formation⁵
• Dentinogenesis imperfecta type II (DGI II): not associated with osteogenesis imperfecta, this type can cause discolouration of the teeth and a bulbous aspect of the crown in both primary and secondary teeth⁵
• Dentinogenesis imperfecta type III (DGI III): also not associated with osteogenesis imperfecta, this type of DGI can cause the crowns to appear bell-shaped and shell-like (a very thin layer of dentin that can cause exposure of the pulp)⁵

Odontodysplasia

It is a non-hereditary disorder that affects only a few teeth; it consists of a formation of defective dentin and enamel that can appear in thin layers radiographically, with an enlarged pulp chamber and a radiographic aspect of “ghost teeth”.²

Familial tumoral calcinosis (FTC)

FTC is a systemic condition that causes calcification of soft tissue; teeth are usually short with bulbous roots and have obliterated pulp chambers.²^,6

Ehlers-Danlos syndrome (EDS)

EDS is a disorder of collagen production, and in some cases, there can be obliteration of the pulp chamber or pulp stones that mimic dentin dysplasia type II.⁵

Schimke immuno-osseous dysplasia (SIOD)

SIOD is a genetic disorder that often results in discolouration of the teeth and obliteration of the pulp chamber (like in dentin dysplasia type II), besides other characteristic signs and symptoms like renal disease and defective cellular immunity.⁵

Management and treatment

Management of dentin dysplasia type II is symptomatic. Since it is usually less severe than dentin dysplasia type I and other types of dentinogenesis imperfecta, affecting only the primary dentition, the secondary teeth often don’t require extensive treatment.

If tooth wear is severe, it can be mitigated with stainless steel crowns or composite resin restorations to protect the teeth.⁷ Though stainless steel crowns are harder and more durable, suitable for posterior teeth, composite resin has better aesthetic value and can be used for anterior teeth.⁷ Composite resin is also able to cover up discolouration of the teeth if it is intense.⁷ Since these teeth have normal root length, they are not prone to mobility and loss.⁵

As there can be calcification of the pulp or an abnormally shaped pulp chamber of the secondary or permanent teeth, root canal treatment (RCT) is often more difficult to perform.⁵ Patients with dentin dysplasia type II should be encouraged to maintain good oral hygiene to avoid cavities, in order to prevent RTC.

FAQ

What is the difference between dentin dysplasia type I and type II?

Dentin dysplasia type I affects both primary and secondary teeth, causing abnormal root formation (resulting in short, malformed roots), while dentin dysplasia type II affects the primary dentition, causing discolouration of the crown, with normal root formation.⁵

What is the difference between dentin dysplasia type II and dentinogenesis imperfecta?

Dentin dysplasia type II only affects the deciduous teeth, while all forms of dentinogenesis imperfect affect both primary and secondary teeth.⁵

Summary

Dentin dysplasia type II is a genetic disorder that causes discolouration of the primary (deciduous) teeth, often resulting in a yellow, brown, grey or even blue tint to the primary teeth due to issues in the mineralisation of dentin. Secondary teeth often have pulp stones with partial calcification of the pulp chamber, leading to partial obliteration or a flame-shaped pulp chamber. Although similar to other disorders of dentin formation, coronal dentin dysplasia is milder in the sense that it only affects the primary dentition. Treatment and management are often symptomatic, resolving issues like tooth wear through crowns or composite resin fillings; root canal treatment is more difficult in patients with dentin dysplasia type II due to their partial obliteration of the pulp chamber, and should be avoided whenever possible.