Topics

Topic

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Superior third molar tooth

The superior third molar, also known as the maxillary third molar or upper wisdom tooth, is the most posterior tooth in the maxillary dental arch. It typically erupts between the ages of 17 and 25 and exhibits high anatomical variability in size, shape, root number, and orientation. The crown is usually irregularly shaped with multiple cusps, and the roots are often fused, curved, or divergent, complicating extraction and endodontic procedures. The superior third molar articulates with the inferior third molar during occlusion and plays a minor role in mastication. Its location adjacent to the maxillary sinus is clinically significant, as pathologies or surgical interventions can impact sinus integrity.

Synonyms

  • Maxillary third molar

  • Upper wisdom tooth

  • Tooth #1 (right) or #16 (left, depending on dental notation)

  • Posterior maxillary molar

Function

  • Assists in mastication of food, particularly grinding

  • Maintains posterior occlusion and arch length

  • Provides support for adjacent teeth in the dental arch

  • Contributes minimally to aesthetic facial contours

MRI Appearance
T1-weighted images:

  • The tooth enamel appears very low signal (hypointense) due to dense mineral content

  • The dentin and pulp may appear intermediate signal relative to surrounding soft tissue

  • Periodontal ligament space may appear as a thin hyperintense line surrounding the root

  • Bone marrow of the alveolar process is hyperintense due to fatty marrow content

T2-weighted images:

  • Enamel remains signal void, dentin intermediate, and pulp may appear slightly hyperintense

  • Surrounding soft tissue edema or periapical pathology appears hyperintense, aiding detection of cysts or infection

  • Adjacent maxillary sinus is hyperintense due to fluid or mucosa if present

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal, highlighting edema, infection, or cystic lesions

  • Normal tooth structures (enamel and dentin) remain hypointense, while inflamed bone or soft tissue appears bright

CT Appearance

  • Superior third molar is hyperdense, with enamel being densest and dentin slightly less dense

  • Roots, pulp chamber, and surrounding alveolar bone are clearly visible

  • Adjacent air-filled maxillary sinus appears hypodense (black), providing natural contrast

  • CT is particularly useful for impacted teeth, root morphology, periapical lesions, and surgical planning

MRI images

Superior third molar tooth mri axial image -img-00000-00000

MRI images

Superior third molar tooth mri sag image -img-00000-00000