Cementum Flashcards
What’s the role of the root cementum?
- attachment of PDL
- supports the tooth
What’s cementum defined as… (type of tissue + where is is located)
Mineralised connective tissue that lines the root of the tooth
-between dentine and PDL
What’s the composition of the 2 main types of cementum?
CELLULAR:
- cementocytes embedded in extracellular matrix
ACELLULAR:
- lacks cementocytes
which type of cementum is formed first?
Acellular (covers most of root surface)
Which type of cementum is formed fastest? And what can this mean for the incremental lines?
Cellular cementum
- incremental lines are further apart (more deposited per day)
What’s the importance of cementum
- maintain and repair root surface
- connect dentine to PDL
Where is cellular cementum deposited
Apical 1/3
Overlaying cementum
What are the physical properties of cementum.
(colour, hardness, porosity?)
PHYSICAL:
- light yellow colour
- not as hard as enamel but harder than dentine
- porosity, allows for fluid exchange
What’s the difference between primary and secondary cementum?
PRIMARY/ACELLULAR:
-formed first
-coronal region
SECONDARY/ACELLULAR:
-contains cementocytes embedded in extracellular matrix
-radicular region
Where are cellular and acellular cementum distributed?
Cellular = apical 1/3 = radicular
Acellular = coronal
What’s the meaning of intrinsic and extrinsic fibres in cementum?
Intrinsic = fibres only present within the cementum
Extrinsic = fibres inserted from the periodontal ligament into cementum
What’s the meaning of AEFC, CIDC and CMSC in terms of fibres in cementum.
AEFC = acellular extrinsic fibre cementum
- Sharpey’s fibres
CIFC = cellular intrinsic fibre cementum
- no role in tooth attachment
CMSC = cellular mixed stratified cementum
- AEFC and CIDC both present in alternating layers
What classifies as a Sharpey’s Fibre?
An extrinsic fibre that is produced from alveolar bone and passes through cementum also. (Comes into contact with both)
What is special about the incremental lines in cementum and what are they called?
- unevenly spaced
- lines of salter
What are the long term incremental lines called in cementum?
Striae of Retzius
Outline the process of cementum resorption.
- Stimulus = trauma
- Activation of cells = odonto/cementoclasts (involved in resorption of mineralised bone)
- Attachment = odontoblasts attach to surface of cementum and secrete enzymes
- Resorption = enzymes break down the mineralised matrix.
- Small cavities are left
What’s the structure of the cementum-PDL interface?
- intrinsic + extrinsic fibres
- Sharpey’s fibres
What’s the composition of cementum?
Hydroxyapatite
Extracellular matrix (Collagen type 1 & non-collagenous proteins)
Non-crystalline forms of calcium (demineralises easier)
What triggers cementum resorption?
Masticatory forces cause micro-trauma = small areas of resorption.
Outline cementum repair after resorption.
- Mesenchymal stem cells from PDL or pulp to site of resorption
- Stem cells differentiate into cementoblast-like-cells + deposit cementum
- Mineralisation of newly formed matrix
What’s the name of the line separating repair tissue and normal tissue in cementum?
Reversal line
If there is resorption causing trauma is it likely to move into dentine or remain just in the cementum?
Remain in cementum
