Introduction

Dentin dysplasia type I (DD-I) is a condition that affects dentin formation in the teeth. It is also known as radicular dentin dysplasia. Dentin is the hard tissue inside the teeth. The dentin layer lies beneath the layer of enamel. Enamel is the outer layer of teeth. It is characterised by normal enamel and coronal dentin formation, but presents with defective root development and abnormal radicular dentin. People with this condition are often born with crowns that look completely normal, but the roots underneath are malformed. Dental X-rays of affected teeth show characteristic radiographic hallmarks. These include short roots or absence of root formation, obliterated pulp chambers and canals, and periapical radiolucencies.¹ This article gives an overview of dentin dysplasia type I and its characteristic radiographic features.

Overview of Dentin Dysplasia Type I

Epidemiology

Dentin dysplasia type I is a rare dental condition. It has an estimated prevalence of around 1 in 100,000 individuals.²

Aetiology and Pathophysiology

The causes and underlying mechanisms of Dentin Dysplasia Type I include:¹

• Dentin dysplasia type I is an inherited genetic condition. It shows an autosomal dominant pattern
• The condition is associated with mutations in several odontogenesis (tooth development) related genes, most notably DSPP (dentin sialophosphoprotein)
• These mutations disrupt the normal function of odontoblasts, the cells responsible for dentin formation
• Abnormal odontoblast activity leads to defective dentin deposition in roots, producing short or absent roots and obliteration of pulp chambers and canals

Clinical Features

Various clinical features include:^1,2

• The crowns of the teeth usually look normal in shape and colour, sometimes slightly amber or bluish-brown in primary teeth
• The roots are short, conical, pointed, or almost absent in some cases
• Both primary (baby) and permanent (adult) teeth are affected
• Teeth often show abnormal sudden mobility because of poor root support
• Patients frequently develop abscesses, granulomas, or cysts even when teeth are not decayed
• Teeth may exfoliate (fall out) prematurely due to root weakness
• Malocclusions such as crossbite, wide diastemas (spacing), and abnormal tooth positioning can be seen
• A positive family history is frequent, as the condition is usually inherited in an autosomal dominant pattern

Differential Diagnosis

Various differential diagnoses include:¹

• Dentin Dysplasia Type II
• Dentinogenesis Imperfecta
• Systemic and syndromic conditions causing premature tooth loss. These include:
  • Kostmann syndrome
  • Cyclic neutropenia
  • Chediak–Higashi syndrome
  • Langerhans Cell Histiocytosis
  • Papillon–Lefèvre syndrome
  • Hypophosphatasia
  • Vitamin D–resistant rickets

Treatment

Various treatment options include:¹

• Patients are advised to maintain proper oral hygiene and frequent dental check-ups to prevent caries and periodontal disease
• It is advised to preserve natural teeth as long as possible despite poor root support
• Applying preventive measures, such as fluoride and sealants are advised to protect enamel
• Root canal treatment is usually not possible due to obliterated pulp canals
• Teeth with pulp necrosis, recurrent abscesses, or severe mobility are often best managed by extraction
• Prosthetic rehabilitation which includes removable dentures, overdentures, or adhesive bridges, is advised in younger patients
• Dental implants may be placed in adults once jaw growth is complete
• Psychological support is important for children and adolescents coping with early tooth loss and functional or aesthetic problems

Radiographic Hallmarks

The definitive diagnosis of DD-I relies upon radiographic imaging, as clinical findings may be unremarkable. The three most important radiographic hallmarks are short roots or absence of roots in some cases, obliterated pulp chambers and pulp canals, and periapical radiolucencies. The various radiographic features include:^1,2,3

Short or Absent Roots

• Radiographs typically show teeth with extremely short, conical, or pointed roots, and in severe cases, roots may be almost completely absent
• The crown-to-root ratio is reduced
• Root apices often show sharp, constricted, or tapered endings, a distinctive feature on panoramic and periapical films
• These root anomalies reflect defective odontoblast function and abnormal dentin deposition during root development, preventing normal elongation

Obliterated Pulp Chambers

• Radiographic images often show pulp chambers and root canals that are partially or totally obliterated by irregular dentin
• In affected cases, crescent or half-moon shaped remnants of pulp chambers remain, typically parallel to the cemento-enamel junction
• These findings result from aberrant dentin formation encroaching into the pulp space, beginning early in tooth development
• Pulp obliteration makes endodontic treatment technically challenging or impossible, as canals are difficult to locate
• On cone-beam CT, the obliteration can be visualised in three dimensions, often confirming the absence of normal pulp structure

Periapical Radiolucencies

• A hallmark of DD-I is the presence of well or ill-defined radiolucent lesions around root apices in teeth that are otherwise intact and non-carious
• These radiolucencies may represent chronic periapical inflammation, granulomas, or cysts resulting from pulp necrosis
• Importantly, such lesions occur without caries or trauma, which should immediately raise suspicion for DD-I
• Multiple teeth are often affected at the same time, especially in the posterior regions
• These periapical findings are thought to develop because pulp necrosis arises from compromised pulp vascularity and abnormal internal dentin, not from external decay

FAQs

Various frequently asked questions include:^1,2,3

Why is DD-I also called radicular dentin dysplasia?

Because the main defect affects the roots (radicular portion) of the teeth rather than the crown.

Does DD-I affect both primary and permanent teeth?

Yes, both dentitions are typically involved.

Is it something that runs in families?

Yes. DD-I is usually inherited in an autosomal dominant pattern, which means if one parent carries the gene, there is a 50% chance of passing it on to their children.

Can it occur even if no one else in the family has it?

Although rare, new genetic mutations can happen in children without any family history.

Are there any lifestyle or environmental risk factors?

No. This condition is purely genetic and is not caused by diet, habits, or environment.

What is the most common clinical complaint?

Loose teeth and premature tooth loss.

Can radiographs alone diagnose DD-I?

Yes, radiographs are the key diagnostic tool when combined with history.

Which imaging is best for diagnosis?

Panoramic and periapical radiographs are useful, but cone-beam CT provides better 3D visualisation.

Is there a cure for DD-I?

No, treatment focuses on the prevention and management of complications.

What is the long-term prognosis?

Teeth are usually lost earlier than normal; prosthetic rehabilitation maintains function.

Summary

Dentin dysplasia type I, also known as radicular dentin dysplasia, is a rare inherited dental anomaly with a prevalence of about 1 in 100,000 individuals. It is usually transmitted in an autosomal dominant manner and linked to mutations in genes. It is recognised by its characteristic radiographic hallmarks of short or absent roots, obliterated pulp chambers, and periapical radiolucencies in clinically normal-looking teeth. Although the crowns appear unaffected, the underlying root defects lead to mobility, premature tooth loss, and frequent periapical pathology. Differential diagnosis includes other hereditary dentin disorders and systemic conditions such as Dentin Dysplasia Type II, Dentinogenesis Imperfecta, etc.  Since endodontic treatment is often not feasible, treatment focuses on prevention, careful monitoring, timely extraction of non-restorable teeth, and prosthetic rehabilitation to maintain function and aesthetics. With regular dental care, preventive strategies, and multidisciplinary support, patients with DD-I can achieve improved oral health outcomes and quality of life despite the challenges posed by this condition. Ongoing research into the genetic mechanisms underlying DD-I holds promise for earlier diagnosis and, potentially, future targeted therapies.