Preclinical Paediatrics · MU Sofia

15. Morphology of dental cementum.

Explains that root cementum is a avascular, aneural mineralised tissue that keeps growing with age without bone-like remodelling, and how it resembles and differs from bone. Covers the three types of cemento-enamel junction with their approximate frequencies, then classifies cementum by location, cellularity, collagen fibril content and fibre origin. Ends with the named types (AAC, AEFC, CIFC, MC) and intermediate cementum, with their sites and roles in anchorage.

Inside: 1 section · 4 labelled pictures · 12 flashcards · 4 min

Topic 15 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 1 section, about 535 words (4 min of reading), with 12 flashcards.

In this note

  1. MORPHOLOGY OF DENTAL CEMENTUM

MORPHOLOGY OF DENTAL CEMENTUM

Root cementum is a hard non-vascularised and non-innervated mineralized tissues that covers the root of the tooth. Does not have ongoing remodelling like bone but continues to grow with age. It resembles bone as the cells are located in lacunae and growth in canals. Differs from bone as it has a lack of blood vessels and nerves.

Cemento-Enamel Junction

  • In 30% of teeth, enamel and cementum meet at the cementoenamel junction as a butt joint at the cervical margin
  • In 60% of teeth, the cementum overlaps the enamel
  • In 10% of teeth, there is a gap between the cementum and enamel leading to sensitivity at this site

Classification of Cementum

By location:

  • Radicular Cementum: cementum found on the root surface
  • Coronal Cementum: forms on the enamel covering the crown

By Cellularity: Cementum containing cementocytes in lacunae within the cementum matrix.

  • Cellular Cementum:
  • Acellular Cementum: cementum without any cells in its matrix

By presence of collagen fibrils in the matrix:

  • Fibrillar Cementum: cementum with a matrix that contains well-defined fibrils of type I collagen fibrils
  • Afibrillar Cementum: cementum that has a matrix devoid of detectable Type I collagen fibrils but have a fine, granular consistency

By Origin of Matrix Fibres (applies only to fibrillar forms of collagen):

  • Extrinsic Cementum: contains primarily extrinsic fibres (e.g. sharpey’s fibres that are produced by periodontal ligaments but are present in cementum). Oriented more perpendicular to the cementum surface and play major role in tooth anchorage
  • Intrinsic Cementum: contains mainly intrinsic fibres (e.g. cementocytes) plays no role in tooth anchorage. Orientated parallel to the cementum surface and found in places where there is a repair of cementum after surface resorption
  • Mixed Fibre Cementum: extrinsic and intrinsic fibres

Types of Cementum

  • AAC- Acellular afibrillar (primary) cementum:
  • Mainly composed of mineralised matrix without fibrils or cementocytes. Produced by cementoblasts, typically found as coronal cementum over enamel and dentin in proximity to cementoenamel junction
  • AEFC- Acellular Extrinsic Fibre Cementum:
  • Matrix has well defined extrinsic Type I Collagen fibrils, part of the densely packed Sharpey’s Fibres that are continuous with principle fibres of PDL
  • Located at cervical 2/3 of root and plays a role in tooth anchorage to the PDL
  • CIFC- Cellular Intrinsic Fibre Cementum:
  • Contains Cementocytes in a matrix composed of almost only intrinsic fibres
  • Located at sites of cementum repair and plays no role in tooth anchorage
  • Can be covered with extrinsic fibres or mixed cementum

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