His Tooth is Funny Looking. What is It?

Patient Presentation
A 9-month-old male came to clinic for his well child examination. He was developmentally appropriate and was gaining good weight and height. His mother’s concern was that he had a tooth that looked abnormal to her. “He’s got 3 teeth but one of them looks longer than it should be,” she said.

The pertinent physical exam showed a well-appearing male with growth parameters in the 25-90% and tracking. His physical examination was normal except for his dentitia. His left mandibular central incisor and lateral incisor appeared normal. Where the right mandibular central and lateral incisor would be appeared to have 1 tooth. There was a slightly deeper indentation in the center of the tooth. All 3 teeth were not loose and the soft tissue surrounding them was normal. The coloration of the teeth was consistent across all the teeth and appeared normal. The eruption level of the all the teeth was symmetric.

The diagnosis of a healthy male with an abnormal tooth was made. A pediatric dental resident was rotating in the clinic and he diagnosed the patient with a single tooth that was most likely a fused tooth. “It can be hard to tell if it is a fusion or a germination problem at this point because he has so few teeth, but it looks healthy and normal. Some people call these double teeth,” he stated. “There’s nothing specifically we have to do now and mom can just do his regular oral care. I’m excited because the mom wants to bring him to see us in our dental clinic so I set up an appointment and I will get to see him again,” he said.

Teeth are specialized anatomic parts of the human body that are developed between the ectoderm and ecomesenchyme in a complex process called odontogenesis. More than 300 genes have been identified that influence odontogenesis. Dental abnormalities can have significance for cosmesis, malocclusion, dental caries and periodontal diseases. It is not uncommon for more than 1 area to be affected. For example, Hutchinson teeth which are caused by congenital syphilis are smaller with wider spacing between the teeth within the arch, and also have a characteristic notching.

Learning Point
Some common dental problems that may be seen or heard about by pediatricians include:

  • Tooth eruption
    • Ankylosis
    • Natal teeth
      • Usually prematurely erupted primary teeth that are present at birth
      • Neonatal teeth erupt in first month
      • Usually lower incisors (85%) and maxillary incisors (11%)
  • Developmental issues
    • Number
      • Anodontia
        • No teeth
      • Hypodontia
        • 1 or more fewer teeth
        • Common, usually in permanent dentitia
        • Etiology – genetic and includes:
          • Albright hereditary osteodystrophy
          • Crouzon’s syndrome
          • Down syndrome
          • Ectodermal dysplasia
          • Ellis-van Creveld
          • Hallermann-Streiff
          • Incontinentia pigmenti
      • Hyperdontia
        • Increased number of teeth
        • More common in permanent teeth especially maxillary incisors
        • Etiology includes:
          • Apert syndrome
          • Cleidocranial dysplasia
          • Craniometaphyseal dysplasia
          • Oral-Facial-Digital
    • Size
      • Microdontia
        • Smaller teeth than usual, generally uncommon
        • Maxillary lateral incisors and molars
        • Etiology includes:
          • Down syndrome
          • Pituitary dwarfism
      • Macrodontia
        • Larger teeth than usual
        • Etiology includes:
          • Hemifacial hyperplasia
          • Pituitary gigantism
    • Shape
      • Germination
        • Formation of two teeth from same follicle with evidence that separation was attempted
        • Often in maxillary anterior region
        • Etiology unknown
      • Fusion
        • Union of enamel and dentin in two or more separate developing teeth
        • Occurs more often in deciduous teeth
        • Etiology unknown

        Note: Germination and fusion problems may look very similar. Each has one joined/enlarged tooth, but the total tooth count is normal in germination defects and is one less in fusion defects when the anomalous tooth is counted as 1 tooth.

      • Concrescence
        • Two adjacent teeth unionized by cementum alone; dentin and roots are separated
        • Frequent in posterior maxillary teeth
        • Etiology is thought to be spacing issues, trauma, increased pressure or infection
      • Dens evaginatus
        • Cusp-like elevation in the central groove
        • Etiology – multifactorial
      • Dens invaginatus
        • Deep surface invagination of the crown lined by enamel
        • Maxilla and maxillary lateral incisors
        • Etiologies that are thought to be causal include:
          • Infection
          • Occlusal pressure
          • Trauma or pressure thought to be causal
      • Dilaceration
        • Abnormal angulation of the root relative to the crown
        • Can occur in all teeth
        • Etiology includes:
          • Axenfeld-Rieger syndrome
          • Ehlers-Danlos syndrome
          • Ichyosis, congenital
          • Smith Magenis syndrome
          • Trauma
      • Enamel pearls
        • Ectopic enamel globule(s) attached to the root
        • Maxillary molars are commonly affected
        • Cause abnormalities of enamel formation
      • Peg shaped laterals
        • Conical, undersized, tapered maxillary lateral incisor
        • Etiology – genetics and endocrine problems
      • Taurodontism
        • Body and pulp chamber are displaced apically in a multirooted tooth such that the pulp chamber is larger
        • Molars are commonly affected
        • Etiology includes:
          • Down syndrome
          • Ectodermal dysplasia
          • Kleinfelter’s syndrome
          • Mohr syndrome
          • Orofacial digital syndrome
          • Trichondento osseous syndrome
      • Talon cusp
        • Extra surface cusp
        • Most occurs in permanent dentitia in the maxilla mainly
      • Structure
        • Enamel abnormalities – amelogensis imperfecta
        • Dentin abnormalities – dentinogenesis imperfect
        • Multiple structural abnormalities – regional odontodysplasia
  • Enamel hypocalcification
    • Fluorosis
    • Infection
    • Inherited diseases
    • Medications
    • Metabolic disorders
    • Malnutrition
    • Rickets
    • Birth-related trauma
  • Post-developmental tooth loss
    • Trauma
    • Erosion – bulimia
    • Internal or external resorption
  • Environmental discoloration or staining – a review can be found here.

    Questions for Further Discussion
    1. What are indications for referral to a dentist?
    2. When is the recommended age for the first dental visit for children?
    3. At what age do primary dentitia erupt?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

    Information prescriptions for patients can be found at MedlinePlus for these topics: Tooth Disorders and Child Dental Health.

    To view current news articles on this topic check Google News.

    To view images related to this topic check Google Images.

    To view videos related to this topic check YouTube Videos.

    Shrestha A, Marla V, Shrestha S, Maharjan IK. Chussid S. Developmental Anomalies Affecting the Morphology of Teeth – A Review. RSBP 2015:12(1)68-78.

    Chussid S. Abnormalities of Teeth.
    Available from the Internet at http://www.columbia.edu/itc/hs/dental/d7710/client_edit/dental_anomalies.pdf (cited 2/27/18).

    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa