From Volume 47, Issue 9, October 2020 | Pages 729-738
Supernumerary teeth can develop in any location of the mandible or maxilla and may have a significant impact on the developing dentition. This paper reviews the prevalence, aetiology and classification of supernumerary teeth. It also describes their clinical characteristics and management options. A case report involving the interdisciplinary management of delayed eruption of central incisors due to the presence of a supernumerary tooth is outlined.
A supernumerary tooth is one that has developed in addition to the normal complement of teeth within the dentition.1,2 Supernumerary teeth can occur in isolation or, less commonly, in association with a number of developmental medical disorders.3
They may be single or multiple, unilateral or bilateral, and can occur in the maxilla and/or mandible.1,2,4 Supernumerary teeth are thought to occur in the maxilla up to 10 times more frequently than the mandible.2 The most common location involving one or two supernumerary teeth only is the premaxilla followed by the mandibular premolar region. The mandibular premolar region, however, appears to be the site in which multiple supernumerary teeth are most frequently located.4
Supernumerary teeth can cause problems during development of the dentition and may require removal and interdisciplinary management in some situations. The aims of this paper are to:
In addition, a case report involving the interdisciplinary management of delayed eruption of two maxillary central incisors due to the presence of a supernumerary tooth is outlined.
The prevalence of supernumerary teeth in the primary dentition ranges from 0.3 to 0.8%, and in the permanent dentition from 1.2 to 3.5%.4 Supernumeraries in the primary dentition, however, may be under-reported. As spacing is commonly present in the primary dentition, supernumerary teeth may erupt into reasonable alignment and remain undetected at, or exfoliate prior to, initial dental inspection.1
Males appear to be more likely than females to present with a supernumerary in the permanent dentition.4,5 Ratios from 1.3:1 to 2.64:1 have been reported.6,7 The broad range of ratios may be due to the wide variety of methodologies adopted in assessing supernumerary teeth and may reflect the varying age ranges and populations assessed.7
Sexual dimorphism does not appear to be present in the primary dentition.1 Those who present with a supernumerary in the primary dentition, however, may demonstrate a higher prevalence of supernumerary teeth in the permanent dentition.8
The majority of patients present with one or two supernumerary teeth.9 Although multiple supernumerary teeth can occur in isolation (Figure 1), they are more commonly seen in patients with an associated syndrome or medical disorder (Table 1).3,10 In rare cases, the presence of multiple supernumerary teeth may be an important indicator of an undiagnosed medical disorder.11 The syndromes and medical disorders most frequently associated with supernumerary teeth are cleft lip and palate (CLP), cleidocranial dysplasia (CCD) and familial adenomatous polyposis.3,6
| Cleft lip and/or palate |
| Classical Ehlers-Danlos syndrome |
| Cleidocranial dysplasia |
| Ellis-Van Creveld syndrome |
| Familial adenomatous polyposis/ |
| Gardner's syndrome |
| Fabry disease |
| Hypermobile Ehlers-Danlos syndrome |
| Incontinentia Pigmenti |
| Kreiborg-Pakistan syndrome |
| Nance-Horan syndrome |
| Neurofibromatosis Type 1 |
| Opitz GBBB syndrome |
| Papillon-League syndrome |
| Robinow syndrome [Dominant form] |
| Rubinstein-Taybi syndrome [RSTS1] |
| Trichorhinophalangeal syndrome |
The prevalence of supernumeraries in patients with CLP is reportedly between 1.9 and 10% and they are thought to be a result of disruption of the dental lamina during cleft formation.6,12 They are the second most common anomaly found in the cleft area.12 Patients with a history of anterior conical or tuberculate supernumerary teeth at an early age have a one-in-four chance of later developing single or multiple supernumerary premolars.7
CCD is a rare autosomal dominant developmental disorder. Associated characteristics include persistent open cranial sutures, hypoplasia/aplasia of the clavicles and dental anomalies including multiple unerupted supernumerary teeth.13
A recent review, however, has suggested that some disorders where few individuals display the presence of supernumerary teeth could be coincidental rather than a true association.3
The aetiology of supernumerary teeth is not fully understood.1,6,14 Environmental and genetic factors have been implicated. Three main theories have been proposed:2,4,7,15
The available evidence appears to support the dental lamina hyperactivity theory and discount the Atavistic and Dichotomy Theories.8 Current thinking indicates a genetic or, more likely, a multifactorial basis to supernumerary development.1,5,6
A genetic basis is suggested as supernumeraries appear to:
Investigations into tooth development in the mouse have also demonstrated a genetic premise for supernumerary tooth formation. Although a genetic element is the component most closely associated with supernumerary teeth, transcription factors and separate molecular signalling pathways are likely to play a part too.6,22
For example, it has been shown that inappropriate regulation by the RUNX2 gene (involving the transcription factor CBFA1) of the activity of the signalling molecule called Sonic Hedgehog (Shh) may be involved in the formation of supernumerary teeth in individuals with CCD.1,22
Supernumerary teeth are usually classified according to morphology (Table 2) or location (Table 3). A supernumerary tooth that has a similar morphology to a ‘normal’ tooth is described as eumorphic, whereas supernumeraries that bear little resemblance to ‘normal’ teeth are described as dysmorphic.23
| Type of Supernumerary | Frequency (%) | Common Locations | Typical Clinical Appearance |
|---|---|---|---|
| Conical | 75 | Anterior maxilla (commonly between central incisors) |
|
| Tuberculate | 12 | Anterior maxilla |
|
| Supplemental | 7 | Any location (most commonly a permanent maxillary lateral incisor) |
|
| Odontome | 6 | Anterior maxilla (compound) and posterior mandible (complex) |
|
| Type of Supernumerary | Characteristics |
|---|---|
| Mesiodens |
|
| Paramolar |
|
| Distomolar |
|
| Parapremolar |
|
Supplemental types (Figures 2–4) are most likely to erupt, followed by conical and tuberculate.6Figure 5 shows an upper right unerupted distomolar.
Although odontomas and supernumeraries have been classified as separate entities, they appear to be the manifestation of the same odontogenic hyper-productive process from an etiopathogenetic and a clinical perspective.24 As a result, odontomas are commonly classified as a morphological supernumerary variant.
A supernumerary tooth may just be a ‘chance’ discovery on a radiograph and have no effect on the dentition.7,23 In many instances, however, a variety of effects can be seen and may be the first indication of the presence of a supernumerary.
The most common complication from a supernumerary tooth is failure of eruption of a permanent maxillary incisor.9,25
Delayed eruption of associated teeth has been reported to occur in up to 60% of Caucasians with supernumerary teeth.26Figure 1 shows a supernumerary tooth impeding the eruption of an upper right second permanent molar tooth.
A supernumerary tooth located between the roots of adjacent teeth may obstruct root approximation, resulting in a diastema. Displacement may vary from a mild rotation to complete displacement.7,9
Erupted supplemental teeth most often cause crowding, although eruption of any supernumerary type can result in crowding (Figure 2).9,27
A previously undiagnosed or a late developing supernumerary may prevent space closure during orthodontic treatment.23,28
Dentigerous cyst formation is a complication that may be associated with a supernumerary tooth.29 Root resorption, dilaceration and abnormal root development of associated permanent teeth have been reported to occur in association with supernumerary teeth, but all are rare occurrences.7,30
Migration of the supernumerary into the nasal cavity and hard palate has been reported in the literature but is very uncommon.31,32
Careful clinical and radiographic examination is essential to identify and localize supernumerary teeth.6
Management is dependent on supernumerary type and position and its effect or potential effect on the dentition, and should be the result of a risk-benefit assessment.33 It may be prudent to liaise with an orthodontist and/or an oral surgeon, particularly as management should be undertaken in conjunction with the correction of any underlying malocclusion.1,14,34
A dental pantomogram (DPT), an upper standard occlusal and/or a long-cone periapical radiograph may be used in combination to localize a supernumerary tooth via the parallax technique.35 A lateral radiograph of the incisor region may assist in its location.9
Cone beam computed tomography (CBCT) may be required to localize its position more accurately and can facilitate more precise assessment of resorption in adjacent roots.36–39
In many situations, no intervention is necessary. If there is considerable risk of damage to the roots of teeth adjacent to the supernumerary, or its position is unlikely to obstruct tooth movement in prospective orthodontic treatment, then removal may not be indicated.40 Early identification and treatment of supernumerary teeth is often advised to minimize complications. If the supernumerary is located close to developing roots, however, delaying removal until root development is complete may be recommended.41 This is to minimize the risk of irreversible damage to developing roots.
Where further dental development is anticipated or a decision made not to remove a supernumerary, regular monitoring of the patient with relevant radiographic investigation at intervals agreed between the patient and his/her general dental practitioner (GDP) and/or other oral healthcare providers is recommended.37,38
Removal is indicated if the supernumerary:
Removal of a supplemental supernumerary tooth is commonly indicated due to crowding, displacement of adjacent teeth and challenges associated with orthodontic inter-arch correction, if it is retained. Timely extraction of a supplemental lateral incisor, for example, may result in self-correction and satisfactory alignment.15 In this situation, the choice of tooth for extraction is based on:
Figures 6 a–c show the pre-treatment radiographs and CBCT images of a 9.5-year-old Caucasian male who was referred by his GDP to an orthodontist regarding failure of eruption of his maxillary central incisors. Royal College of Surgeons of England guidelines recommend that further investigation is warranted if:
Radiographic investigation revealed the presence of a supernumerary tooth. Following discussion with the patient's family, it was decided to bond attachments to the unerupted central incisors at the same time as removal of the supernumerary tooth. The patient underwent a course of sectional fixed appliance treatment to create sufficient space, facilitate guided traction and alignment of the incisors (Figures 7–9). Careful post-treatment monitoring will be required as patients with an anterior maxillary supernumerary tooth may be at increased risk of developing one or more late forming supernumerary teeth, especially in the lower premolar region.
Supernumerary teeth are not uncommon and can be associated with a variety of effects on the dentition. The GDP should be aware of the characteristics that may indicate their presence, including delayed eruption of teeth and crowding, and should be able to carry out appropriate clinical and radiographic assessment. Once diagnosed, each patient should be managed appropriately to minimize (potential) deleterious effects to the dentition.
This may require interdisciplinary involvement of an orthodontist and oral surgeon in the patient's care.
