Preclinical Paediatrics · MU Sofia

14. Histogenesis of dental cementum.

Explains how root cementum forms, beginning with the dental follicle and Hertwig's epithelial root sheath, which induces cementoblast differentiation. It then walks through the two stages of cementogenesis (organic matrix formation with its Sharpey's and cementoblast-derived fibres, then mineralisation into hydroxyapatite), the fate of the root sheath as epithelial rests of Malassez, and the difference between acellular and cellular cementum in multirooted teeth. A table lists the processes of root development and two labelled pictures are included.

Inside: 5 sections · 2 labelled pictures · 1 table · 16 flashcards · 9 min

Topic 14 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 5 sections, about 1,219 words (9 min of reading), with 16 flashcards.

In this note

  1. HISTOGENESIS OF DENTAL CEMENTUM
  2. Desintegration of the Hertwig`s root sheat end formation of cementum end periodontal ligaments
  3. processes during root development
  4. Multi-Rooted Sheath
  5. The Fate of Hertwig’s Epithelial Root Sheath

HISTOGENESIS OF DENTAL CEMENTUM

Root cementum is a hard non-vascularised and non-innervated tissues that covers the root of the tooth. Does not have ongoing remodelling like bone but continues to grow with age

  • Origin: from the third element of dental germ, dental follicle after stimulation by Hertwig’s Epithelial Root Sheath formed by dental sac

Cementum Formation involves two tissues- Mesenchyme of the tooth follicle and the ectoderm of the Hertwig’s Root Sheath

Histogenesis of Cementum = Cementogenesis

Formation of cementum is called Cementogenesis and is due to cementoblasts and occurs right after the enamel has completely formed.

Hertwig’s Root Sheath

  • The outer and inner enamel epithelia of enamel organ forms Hertwig’s Epithelial Root Sheath which is responsible for determining the shape of the root
  • Two epithelial layers which are separated by stratum intermedium and stellate reticulum- which are connecting in the area of the future enamel cementum junctions (CEJ) and form the cervical loop
  • There is a proliferation in depth to the dental follicle, as stratum intermedium and stellate reticulum are pushed out. This proliferation is called Hertwig’s Epithelial Root Sheath. It is located at the cervical loop of the enamel organ
  • Function is to stimulate mesenchymal cells of dental follicle to differentiate

Three Layers of cells of Dental Follicle are formed:

  • Innermost cells: differentiates to cementoblasts- build the cementum
  • Middle Layer: differentiates into fibroblasts to build the PDL
  • Outermost cells: differentiates to osteoblasts- build the alveolar bone

Stimulation of the Hertwig’s Root sheath initiates the formation of the root dentin by differentiation of odontoblasts from the dental papilla

  • Both epithelial layers merged apically into one
  • At its end are 4-5 cells without proliferation
  • The do not divide by direct proliferation of the Hertwig’s Epithelial Root Sheath in order to control its length, thickness, curvature and number of roots

Cementoblasts deposit a thin acellular cementum over the root dentin called intermedium cementum. It plugs up dentinal tubules and isolates and protects the dentin.

  • First layer of cementum serves as basis for building the cementum

induced by the proliferation of dental sac /dental follicle

Root sheath disintegrates but residual pieces that do not completely disappear are seen as epithelial cell rest of Malassez (ERM)

  • Epithelial cells are grouped into clusters of 3-4 cells which are quickly removed from the root surface. It separates from the organic matrix secreted by cement regions

Continue reading free

The whole note, all 5 sections, is free with an AceMed account, with its 16 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note