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Root of lower molar tooth

The root of a lower molar tooth is the part of the tooth embedded in the alveolar bone of the mandible, anchoring the tooth securely within the jaw. Lower molars typically have two roots (mesial and distal), though some may have an additional distolingual root, depending on the specific tooth and individual variation. Each root contains the root canal system, which houses the dental pulp, nerves, and blood vessels, providing nutrition and sensory innervation to the tooth. The roots are covered by cementum, which connects with the periodontal ligament to allow slight mobility and distribute occlusal forces to the surrounding bone. Understanding the anatomy of the roots is essential for endodontic treatment, extraction, and imaging interpretation.

Synonyms

  • Mandibular molar root

  • Lower molar root

  • Root apex of lower molars

Function

  • Anchors the tooth in the mandibular alveolar bone

  • Houses the pulp tissue containing nerves and blood vessels

  • Provides structural support during mastication

  • Serves as a conduit for neurovascular supply to the tooth

  • Transmits occlusal forces to surrounding bone via the periodontal ligament

MRI Appearance
T1-weighted images:

  • Roots appear as low-signal (hypointense) structures within hyperintense bone marrow in the mandible

  • The pulp canal may appear slightly hyperintense due to soft tissue content

  • Surrounding fat in the marrow provides natural contrast

  • Pathological changes, such as pulpitis or periapical lesions, may show altered signal intensity

T2-weighted images:

  • Roots remain hypointense, while the pulp canal may appear hyperintense, depending on fluid content

  • Periapical edema or cysts appear bright, allowing detection of inflammation or abscess

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal, highlighting edema or inflammatory changes around the root apex

  • Normal roots remain hypointense; periapical infections, abscesses, or bone marrow changes appear hyperintense

CT Appearance

  • Roots are hyperdense, well-corticated structures extending from the crown into the alveolar bone

  • Surrounding trabecular bone appears intermediate density; air in the oral cavity appears hypodense, providing natural contrast

  • CT clearly visualizes root morphology, number of canals, curvature, and any periapical lesions

  • Essential for preoperative planning, assessment of fractures, endodontic evaluation, and detection of pathological lesions

MRI images

Root of lower molar tooth mri sagittal image -img-00000-00000