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Topic

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Superior first molar tooth

The maxillary first molar is the largest posterior tooth in the upper jaw, typically erupting between 6–7 years of age. It usually has three roots—two buccal (mesiobuccal and distobuccal) and one palatal—anchoring it firmly in the maxilla. Its crown is quadrangular or rhomboidal, with four to five cusps (mesiobuccal, distobuccal, mesiolingual, distolingual, and occasionally a fifth cusp of Carabelli). The first molar plays a critical role in mastication, occlusion, and maintaining arch integrity, as it serves as a key posterior anchorage tooth. Root morphology can be complex, with curvatures and accessory canals affecting endodontic treatment and imaging interpretation.

Synonyms

  • Upper first molar

  • Maxillary 6-year molar

  • Permanent maxillary first molar

  • Superior posterior molar

Function

  • Facilitates grinding and crushing of food during mastication

  • Maintains occlusal vertical dimension and posterior support

  • Contributes to arch length and alignment of adjacent teeth

  • Provides anchorage for orthodontic and prosthodontic procedures

MRI Appearance
T1-weighted images:

  • The tooth crown is hypointense (low signal) due to dense enamel

  • The dentin appears slightly higher signal than enamel but lower than surrounding soft tissue

  • The pulp chamber shows intermediate to high signal intensity due to soft tissue content

  • Periodontal ligament may appear as a thin low-signal line surrounding the root

T2-weighted images:

  • Enamel remains very hypointense, dentin is intermediate, and the pulp chamber is hyperintense, clearly differentiating it from hard tissue

  • Surrounding alveolar bone shows intermediate signal, while marrow fat appears hyperintense

  • Useful for evaluating pulpal pathology, periapical inflammation, or cystic lesions

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal in alveolar bone marrow, highlighting edema, infection, or inflammatory changes

  • Tooth structure remains hypointense; periapical lesions or pulpitis appear hyperintense

CT Appearance

  • The tooth is hyperdense, with enamel being the densest and easily distinguishable from dentin and pulp

  • Roots and pulp chambers are well visualized; root curvatures, accessory canals, and periapical bone changes are clearly seen

  • Surrounding alveolar bone is less dense than enamel, with trabecular patterns visible

  • Air in the oral cavity appears hypodense (black), providing natural contrast with the tooth and alveolar bone

  • Ideal for fracture assessment, caries evaluation, endodontic planning, and implant placement

MRI images

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

MRI images

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