Preclinical Paediatrics · MU Sofia

18. Morphology of the periodontium.

Covers the four components of the periodontium: gingiva, periodontal ligament, cementum and alveolar bone. It then describes the principal fibres of the periodontal ligament, grouped into dentoalveolar fibres (alveolar crest, horizontal, oblique, apical and interradicular) and gingival fibres (cemento-gingival, alveologingival, dento-periosteal, circular, transseptal and others). Also covers the oxytalan elastic fibres, collagen composition, blood supply, innervation, and clinical notes on ligament thickness, remodelling and repair.

Inside: 2 sections · 3 labelled pictures · 14 flashcards · 7 min

Topic 18 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 2 sections, about 1,077 words (7 min of reading), with 14 flashcards.

In this note

  1. MORPHOLOGY OF PERIODONTIUM
  2. Clinical facts :

MORPHOLOGY OF PERIODONTIUM

Periodontium is a complex of structures that helps to support the tooth. It consist of four principal components:

  • Gingiva
  • Periodontal ligament
  • Cementum
  • Alveolar Bone

These tissues form a specialized fibrous joint and are thought to be of ectomesenchymal origin

PRINCIPLES FIBRES OF PDL

  • Fibre bundles that exit the cementum and alveolar bone from the periodontal ligament are called the principal fibres.
  • Depending on the location, can be classed as Dentoalveolar fibres or Gingival Fibres
  • Periodontal fibres of periodontal ligament are primarily composed of Bundles of Type I Collagen Fibrils

Classified into several groups based on their anatomic locations

  • (Dental-)Alveolar Fibre Group
  • Alveolar Crest Fibres
  • Near the cervical region, extend obliquely from the cementum just beneath the junctional epithelium to the alveolar crest
  • Prevent tooth’s extrusion and resist to lateral movements
  • Horizontal Fibre Group
  • Near the middle part of root, attach to cementum apical to alveolar crest
  • Attach to cementum and connect root of tooth to alveolar bone
  • Oblique Fibre Group
  • Immediately above the apical group. Most numerous fibres in the periodontal ligament, running from cementum in an oblique direction to insert into bone coronally
  • Apical Fibre Group
  • Near apical area of root, fibres prevent the extrusion of tooth and resist lateral tooth movements
  • Radiating from cementum around root’s apex into the bone, forming the base of the socket
  • Interradicular Group
  • Are only found between the roots of multi-rooted teeth, such as molars. Also attach from the cementum and insert to the nearby alveolar bone

Further classified into two groups, gingival and dentoalveolar group

  • Gingival Group
  • Cemento-Gingival Group
  • Attached to the cementum consists of two types:
  • Free Gingival Fibres are fixed at one end to the cement, and the other ends are freely in the neck cementum (cervical region) -> free gingiva (attached to, freely)
  • Attached Gingival Fibres are attached to the cementum in the neck of the tooth and ending in the attached gingiva cementum (cervical region) -> attached gingiva
  • Alveolar Gingival Fibres
  • Attached to alveolar ridge and end freely in the gingiva
  • Dento-periosteal fibres§
  • Emerge from cervical cement and end in alveolar ridge periosteal -> membrane of bone
  • Circular Gingival Fibres surround tooth cervically
  • Long fibres that circulate the cervix
  • Run along the neck of the tooth and encircle it, found at cervical area
  • Transgingival Fibres proximal
  • Emerge from proximal root surface, pass to adjacent teeth and merge with other vestibular and orally arranged octoid fibres
  • Semicircular Fibres

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