Introduction

Definition of tooth agenesis

Tooth agenesis is a condition in which a person is born without some of their teeth. It can affect both primary (baby) and permanent teeth, but it most commonly affects permanent teeth.¹

There are three main types of dental agenesis:

• Anodontia: it occurs when all teeth do not develop
• Hypodontia: is the absence of one to five teeth
• Oligodontia: is the absence of six or more teeth

Tooth agenesis is more common in females, and it most affects third molars (wisdom teeth), second premolars, and lateral incisors.¹

Importance of early diagnosis and intervention

Detecting tooth agenesis early allows for better treatment planning and improves both your oral function and overall quality of life. Early intervention helps prevent complications such as speech difficulties, misalignments and jawbone deterioration. A well-planned approach ensures that you receive the most effective treatment options, tailored to your needs. Since managing tooth agenesis often requires input from multiple specialists including dentists, orthodontists, and prosthodontics, early diagnosis helps create a coordinated treatment plan that leads to the best long-term results.

Causes and risk factors

Genetic factors

Tooth agenesis often runs in families, with specific genes playing a crucial role in tooth development. Mutations in the following genes have been linked to missing teeth:

• AXIN2: plays a role in both tooth and jawbone development; mutations can cause severe tooth agenesis (oligodontia) and have been linked to a higher risk of colorectal cancer
• MSX1: helps form tooth buds; defects in this gene are associated with premolars and wisdom teeth
• PAX9: important for molar development; mutations can lead to missing molars and other permanent teeth
• EDA: this gene is involved in the development of teeth, hair, and sweat glands. Mutations can cause ectodermal dysplasia, a condition where multiple teeth may be missing or malformed
• LRP6: regulates signalling pathways for tooth formation; mutations can result in hypodontia (missing a few teeth)^1,3

Environmental factors

Certain external factors during early development can also contribute to tooth agenesis. These include:

• Infections during pregnancy, such as rubella, which can interfere with normal tooth formation
• Trauma, like orofacial injuries during early tooth development, which may disrupt tooth growth
• Medications, including thalidomide and some chemotherapy drugs, have been linked to missing teeth
• Radiation exposure, particularly in the head and neck region during dental development, which can affect tooth formation^1,3

Early diagnosis of tooth agenesis

Clinical examination

A thorough examination is essential for diagnosing tooth agenesis. Dentists assess missing teeth by examining both primary (baby) and permanent teeth to determine how many teeth are absent and whether any other dental abnormalities are present.

Certain dental features may indicate tooth agenesis, including:

• Microdontia (unusually small teeth): often seen with missing teeth
• Malocclusion (misaligned bite): gaps or crowding caused by missing teeth
• Retention of primary teeth: baby teeth that do not fall out as expected due to missing permanent teeth underneath⁴

A family history should also be taken, as tooth agenesis often runs in families. If close relatives have missing teeth, the risk of having the condition increases.⁴

Imaging techniques

To confirm the diagnosis and plan treatment, dentists use imaging techniques to get a clear view of tooth development.

• Dental X-rays (Panoramic and Periapical): provide a detailed image of teeth, allowing dentists to see which permanent teeth are missing or delayed in development
• Cone Beam CT (CBCT): a specialised 3D scan used in complex cases to assess the jawbone-structured position of teeth more precisely

Genetic testing

In some cases, genetic testing may be recommended, especially when tooth agenesis is suspected to be linked to a genetic condition like ectodermal dysplasia. This involves analysing specific genes (e.g., PAX9, MSX1, AXIN2) to determine whether a genetic mutation is responsible for the missing teeth. Genetic testing can help guide long-term treatment planning and identify risks for associated conditions.⁴

Intervention strategies for tooth agenesis

Managing tooth agenesis requires a personalised approach, ranging from orthodontic solutions to prosthetic replacements, depending on the severity of the condition. In more complex cases, a multidisciplinary team, including dentists, orthodontists, prosthodontists, periodontists, and oral surgeons may be involved to ensure the best outcomes.²

Orthodontic approaches

• Space maintenance: in cases where permanent teeth are missing, orthodontists may use space maintainers to preserve room for future prosthetic replacements
• Braces or clear aligners: used to close gaps, correct misalignment, and improve bite function, ensuring a well-balanced dental structure

Prosthetic and restorative solutions

• Dental implants: a permanent solution for missing teeth, typically recommended for adults once jaw growth is complete
• Bridges and dentures: alternative options for individuals who are not suitable candidates for implants. Partial dentures may be used in children until they are old enough for long-term treatments

Growth-guided treatment in children

• Monitoring jaw and tooth development: Regular dental check-ups allow early detection of growth abnormalities, helping to plan future treatments
• Temporary aesthetic solutions: Composite bonding or partial dentures may be used to improve appearance and function until more permanent options become available

Long-term management and patient education

Regular dental check-ups

• Monitoring for late-erupting teeth or secondary complications: children with tooth agenesis often experience delayed dental development, requiring regular check-ups to track jaw growth, tooth eruption, and bite alignment
• Adjusting fitted dental appliances as needed: for individuals using removable dentures or orthodontic devices, routine visits ensure proper fit and function as the jaw continues to develop
• Maintaining oral hygiene to prevent additional dental issues: missing teeth can affect chewing and speech, making professional cleanings and fluoride treatments important for preventing decay and gum disease²

Educating patients and families

• Encouraging proactive dental care to improve long-term outcomes: teaching families about good oral hygiene habits, the importance of early intervention, and when to seek specialist input (e.g., orthodontists) ensures better oral health

Summary

Early diagnosis of tooth agenesis through clinical examinations and advanced imaging techniques is crucial for effective treatment. Identifying missing teeth early allows for personalised intervention strategies, including orthodontic care, prosthetics, and multidisciplinary collaboration. Parents and caregivers should prioritise timely dental assessments to ensure early intervention, which can significantly improve long-term outcomes. Dentists are instrumental in guiding patients through treatment options that enhance both oral function and quality of life. By taking proactive steps, individuals with tooth agenesis can avoid complications and achieve healthier, more confident smiles, ultimately leading to better overall well-being.