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Histology Pt.3 - Coggle Diagram

- - - - Functional unit, radial extension from pulp to DEJ and CEJ
      - primary curvature = "s-shape"
      - Density of tubles reduces as we approach the DEJ/CEJ
    - - Forms the sleeve of the dentinal tubular (hypermineralzed)
    - - Lies between the dentinal tubules = forms the bulk of the dentine
    - - Innermost layer of the dentine (nearest to the pulp)
      - unmineralised dentine matrix (collagen and ground substance)
    - - Extensions of the cell bodies in the dentinal tubules
      - Allows for communication between odontoblasts
  - - - Circumpulpal (bulk = 90% of dentine)
        
        Collagen fibers parallel to DEJ, both globular or lineral minerlations may be observed
      - mantle dentine (first, thin) - less minerlaised than circumpulpal
    - - Laid down after root formation (slowly) and continues throughout life
    - - In response to trauma/injury ie caries
      - Odontoblasts and undifferentiated cells lay it down rapidly and often in an irregular way
    - - Loss of processes, just intertubular dentine
  - - - Primary curvature
        
        Schreger Lines
      - Incremental lines - correspond to striate of Retzius
        
        Von Ebner Lines
      - Diturbacnes in minerlaization
        
        Contour lines of Owen
        
        Ex. Neo natal line - mineral deposition thet occurs at birth
  - - - Disturbances in the dentinal fluid cause turbulence which is picked up closely asso. nerve endings and periced as pain
- - - - Incremental lines, or concentric lines
      - Neo-natal lines, refelct the stress during birth
    - - Where striae of Retzius meet fresh enamel
      - Surface remodelling smooths them out over time
    - - optical phenomenon produced by chnages in rod direction
    - - scalloped appearnce
      - Enamel Tufts
        
        Due to abrubt changes to enamel secretion, usually reulting in higher conc. of tuftelin in the enamel (hypo-mineralised)
      - Enamel Spindle
        
        odontoblast process are trapped into the enamel (dark), usually near the cusps of teeth
      - Enamel Lamellae
        
        Unminerlaiised defects
        
        Primary lamellae = fault lines during amelogenesis
        
        Secondary lamellae = as a result of occlusal trauma
        
        Secondary will predispose enamel to fracture
  - - - Due to congentital syphilis
      - Causes notches in teeth
    - - Single tooth enamel hypoplasia
      - May be caused by periapical inflammation overlying the primary tooth as a result of trauma
    - - A group of genetic conditions
      - Results in failed enamel matrix formation
- - - - Part of the periodontium (functionally) and the tooth (anatomically)
      - Thickest at the apex, thinnest at teh CEJ
      - Not innervated/avasculare = no remodelling
      - It can repair! as it is formed throughout life
    - - Anchor the principal fiberd of the periodontium to the tooth root
    - - HERS complex forms (OEE and IEE cells) between the dental papilla and dental sac
      - HERS extends and curves at its ends to form the epithelial diaphragm
        
        determines the no. and shape of the apical formina
      - Cementogenesis
        
        HERS extends apically to form the roots of the developing tooth
        
        Dental follicle cells differentiate into odontoblasts and secret pre-dentine which breaks down the HERS in this region
        
        HERS gone = dental sac cells contain the pre-dentine and differetiate to become cementoblasts
        
        This process continues from the cervix to the apex covering the entre root surface
        
        only at the advancing edge of the devloping root = causing it to lengthen as it developes
    - - softer and more permebale than dentie
      - 65% inorganic and 23% orgnaic, and 12% water
      - Organic = Type 1 collagen fibers (90%) and also Type 3 and 12 collagen, ground substance (inlc cementum attachment protein)
  - - - Cellular Cementum
        
        Rapidly forming = cementocytes founf in the cementum
        
        Apical and furcation areas
      - Acellular Cementum
        
        Coronal 1/2- 2/3s of the root
        
        Slow forming = no cemenoblasts trapped
    - - Intrinsic Fibers
        
        Secreted by cementoblasts
      - Extrinsic Fibers
        
        Secreted by PDL (Sharpey's fibers)
    - - Primary
        
        Before tooth eruption
      - Secondary
        
        Ater tooth eruption
    - - Acellular intrinsic fiber cementum (AIFC)
      - Acellular extrinsic fiber cementum (primary cementum) (AEFC)
      - Cellular intrinsic fiber cementum (secondary cementum) (CIFC)
      - Cellular mixed stratified cementum
      - Acellular afibriliar cementum (at CEJ)
  - - - If trapped in the rapidly forming cementum = forms cellular cementum
      - secrete collagen (intrinsic fibers) along the root surface before they migrate away
    - - produce principal fibers of collagen for cementum (extrinsic fibers)
    - - AIFC is first
        
        collagen produced by the cementoblasts is laid perpenicular to the dentine
      - AEFC follows second
        
        Cementoblasts stop secereting collagen and focus on forming matric proteins to anchor the fibers from the Periodontal fibroblats = Sharpey's Fibers
      - CIFC: At the apical portion
        
        intrinsic fibers are laid down by cementoblasts rapidly, which traps cells, and this occurs after eruption
        
        We find incremental lines of Salter (secondary cementum)
      - CIDF and AEFC may be mised up due to things like orthodontic tooth movement due to rapid formation to adjust new tooth positions
  - - - Acellular intrinsic fiber cementum (AIFC)
        
        inital layer formed at the CEJ and contains intrinsic fibers
      - Acellular extrinsic fiber cementum (AEFC)
        
        Primary Cementum
        
        No cementocytes
        
        extends from CEJ to apical 2/3
        
        Important attachement site for PDL = primarly for tooth anchoring
        
        Sharpey's fibers insert perpendicular to it
      - Cellular intrinsic fiber cementum (CIFC)
        
        Secondary cementum
        
        forms rapidly = incorporated cementocytes
        
        cementocytes point towards PDL (nutrient)
        
        Not involved in tooth anchoring
        
        We see incremental line of Salter
        
        Found in the furcations/apical regions
      - Cellular mixed stratified cementum
        
        Due to adjustments in tooth position, we seen a mixture of shrapey's fibers and intrinisic fibers in the cervical portion and cementocytes may be present as well
        
        Acellular, cellular and intrinisc and extrinisc all coexist
        
        Depends of the rate of formation of cementum
      - Acellular afibriliar cementum (at CEJ)
        
        only found at the CEJ
        
        60% overlap CEJ
        
        30% buttjoint at CEJ
        
        10% have an exposed dentine, no overlap
        
        plays no role in tooth attachement
    - - Resportion fd cementum or root dentine due to trauma (traumatic occlusion, movement, hypereruption)
      - Protective function of cementum
        
        extrinsic fiber cementum (functional repair)
        
        intrinsic fiber cementum (anatomical reapir)
- - - - Peripheral to the pulp and adjacent to the dentine
      - Odontoblasts liver here
        
        Nb: secretory odontoblatss are tall columar epithelial cells, with golgi, eER, and mictochondria capable of secretion
    - - Cell-free-zone of Weil = fenestrated vessels of the subodontoblastic (Raschkow) plexus, and von-korff fibers
      - Cell-rich zone = undiff. mesenchymal cells, fibroblasts, mO, lymphyocytes
    - - contains vessels and nerve fibers (V3)
      - Ab, Ad and C fibers responsible for dull aching, burning, and sharp/shooting pains