Supernumerary Teeth

Supernumerary teeth are teeth in excess of the normal dental formula, arising from the dental lamina in the hyperactive phase of tooth development. They occur in the permanent dentition in about 0.5 to 3.5% of people and in the primary dentition in about 0.3 to 0.8%.

They are classified by shape (conical, tuberculate, supplemental and odontoma like) and by position (mesiodens in the midline, paramolar beside a molar, distomolar behind the third molar, and parapremolar). Males are affected more than females, about 2 to 1.

Pathophysiology. Hyperactivity of the dental lamina, or a split of the tooth bud, produces additional tooth germs. A genetic component is shown by familial cases and syndromic associations.

Conditions linked to multiple supernumerary teeth include cleidocranial dysplasia, Gardner syndrome, cleft lip and palate, Ehlers-Danlos syndrome, Apert syndrome and trichorhinophalangeal syndrome.

Often found on radiographs without symptoms. Features include delayed or failed eruption of the neighbouring tooth, crowding, a midline diastema, rotation or displacement of teeth, malformed roots, an eruption of an extra tooth, a dentigerous cyst and, rarely, resorption of adjacent roots or eruption into the nasal cavity.

Multiple supernumerary teeth, especially in the premolar area, should prompt a search for a syndrome, with examination of the skull, clavicles, skin and bowel.

Rapid swelling, pain or infection need prompt assessment, and a supernumerary tooth associated with a cyst needs surgical review.

• Clinical examination of the dental arch, eruption and spacing, with palpation for unerupted teeth.
• Panoramic and periapical or occlusal radiographs to locate the tooth, using the parallax technique. Cone beam CT for the exact position, relation to adjacent roots, nasal floor and canal, and surgical planning.
• Classification by form, position and orientation.
• Screening for syndromes when teeth are multiple: examination of the clavicles and skull, family history, and referral to genetics. Colonoscopy referral when features of Gardner syndrome exist.
• Histology of extracted teeth when a cyst is present.

Differential diagnosis.

• Compound odontoma
• Retained primary tooth
• Geminated or fused teeth
• Natal or neonatal teeth
• Dentigerous cyst with extra tooth
• Impacted permanent tooth
• Delayed eruption from other causes

• Asymptomatic supernumerary teeth that do not interfere with eruption, cause no cyst and are not near the roots of important teeth can be observed with radiographic review at 6 to 12 months.
• Removal is advised for those that delay or deflect the eruption of permanent teeth, cause crowding, lie close to adjacent roots, form a cyst, or interfere with orthodontic treatment or prosthesis. Timing for anterior teeth is usually when the roots of the neighbouring incisors are half to two thirds formed, around 6 to 8 years, with earlier removal when eruption is blocked.
• Surgical removal under local anaesthesia or general anaesthesia, with a palatal or labial flap and care to protect the roots and tooth germs. Unerupted incisors may need exposure and orthodontic traction if they do not erupt within 6 to 12 months after removal.
• Conical forms may erupt on their own and some are left under observation, while tuberculate forms more often prevent eruption and are removed early.
• Antibiotics are not required for routine removal. A single dose of amoxicillin 500 mg to 1 g orally or cefazolin 2 g intravenously may be used for selected patients.
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food. Children use paracetamol 15 mg/kg every 4 to 6 hours (maximum 75 mg/kg daily) and ibuprofen 5 to 10 mg/kg every 6 to 8 hours.
• Syndromic cases need a multidisciplinary team with orthodontics, genetics and other specialties.

Special groups. Children under 6 need sedation or general anaesthesia and careful risk benefit review of early removal. Patients with cleidocranial dysplasia need a staged treatment plan.

Monitoring. Review at 3 to 6 months after removal for the eruption of adjacent teeth, and every 6 to 12 months for retained teeth, with radiographs. Check the vitality of adjacent teeth.

Referral and escalation. Refer to orthodontics, paediatric dentistry or oral and maxillofacial surgery. Refer to genetics for multiple supernumerary teeth, and urgently for cyst, infection or rapid growth.