Fiber Groups

Principal fibers

Collagen fiber bundles of the periodontal ligament (PDL) that attach cementum to alveolar bone and resist masticatory forces.

Alveolar crest fibers

Run from cervical cementum to alveolar crest; resist lateral tooth movement and extrusion.

Horizontal fibers

Run perpendicular from cementum to alveolar bone; resist horizontal pressure.

Oblique fibers

Most numerous PDL fibers; run diagonally from cementum to bone; resist vertical/intrusive forces.

Apical fibers

Radiate from apex of root to bone; resist extrusive forces and tipping.

Interradicular fibers

Found only in multirooted teeth; run from cementum into interradicular septum; stabilize tooth.

Sharpey's fibers

Terminal ends of principal fibers embedded into cementum and alveolar bone.

Gingival fibers

Collagen fibers located in gingiva that provide structural support and maintain gingival contour; not part of the PDL.

Dentogingival fibers

Extend from cementum into free gingiva; support gingival margin.

Circular fibers

Encircle the tooth within free gingiva; maintain gingival integrity.

Dentoperiosteal fibers

Extend from cementum over alveolar crest into periosteum; stabilize gingiva to bone.

Transseptal fibers

Extend interproximally from cementum of one tooth to cementum of adjacent tooth; maintain tooth alignment even after bone loss.

Oxytalan fibers

Immature elastic fibers in the PDL that run parallel to the root surface and are associated with blood vessels.

Collagen fibers

Strong, inelastic fibers (Type I predominates in PDL) that provide tensile strength.

Elastic fibers

Fibers that provide elasticity; true elastic fibers are mainly found in blood vessel walls, not as primary PDL support.

Principal fibers vs Gingival fibers

Principal fibers attach tooth to bone (PDL); gingival fibers support gingiva.

Oblique fibers vs Horizontal fibers

Oblique fibers resist vertical/intrusive forces; horizontal fibers resist lateral forces.

Apical fibers vs Alveolar crest fibers

Apical fibers resist extrusion at the apex; alveolar crest fibers resist lateral movement at the cervical area.

Transseptal fibers vs Interradicular fibers

Transseptal fibers connect tooth to tooth; interradicular fibers stabilize multirooted teeth.

Sharpey's fibers vs Principal fibers

Sharpey's fibers are the embedded ends of principal fibers within bone and cementum.