OCB02-1019 Structure of cementum and alveolar bone Flashcards
What are the functions of the alveolar bone process?
Necessary for muscle attachment
Contains bone marrow for haematopoiesis
It has storage functions for calcium and phosphate ions
Plasticity and remodelling
What does the growth of the alveolar bone depend on?
Tooth eruption and root formation
What does the alveolar bone rely to for maintenance?
tooth retention because if a tooth is lost, that part of the bone will resorb
When does the alveolar bone initially develop?
In the second month of fatal life
What are the two kinds of bone in alveolar bone?
Compact and trabecular
Which bone has a higher surface area to mass ratio?
Trabecular
What is the purpose of compact bone?
Give attachment to the fibres of the periodontal ligament
What is bundle bone?
Another term for compact bone due to the bundles of fibres attaching from the periodontal ligament
What fibres of the periodontal ligament are embedded in the bundle bone?
Sharpey’s fibres
What are the arrangement of sharpey’s fibres?
They are perpendicular to the bone
What is lamina dura?
On the radiograph , the bundle bone is more radio dense as the thick bone is seen without trabeculations
What is the cribriform plate?
An opening in the alveolar bone which is perforated by blood vessels and nerve
What are the names of the 2 septums within the alveolar bone?
Interradicular septum
Interdental septum
What is interradicular septum?
Separates the individual roots of a multi rooted tooth
What is interdental septum?
Separates two individual teeth
What is the blood supply to the alveolar bone?
Periodontal
Alveolar
Supraperiostal/ mucogingival
What is the nerve supply to the alveolar bone
Mesencephalic sensory neurons of the trigeminal nerve
Motor nucleus of the trigeminal
Sensory nucleus of the trigeminal
Spinal sensory trigeminal
What is type I trabecular bone?
the trabecular are regular and horizontal
What is trabecular bone most commonly found?
Mandible
What is type II trabecular bone?
irregularly arranged and numerous trabeculae
Where is type II trabecular bone found?
Maxilla
Where is trabecular bone the most dense?
most dense next to the teeth where it forms the cribriform plate
How does tooth loss affect the alveolar bone?
It degrades the bone
What is a resting line?
When bone deposition is halted then resumed
What is a reversal line?
Resorption by osteoclasts
What is cementum?
Bonelike tissue that covers the root of your teeth
What cells make cementum?
cementoblasts
What are the functions of cementoblasts?
It joins the enamel at the cervix of the tooth creating a cement-enamel junction
Cementum attaches the teeth to the alveolar bone by anchoring the PDL
Cementum anchors the gingival and periodontal fibres
Protects dentin
What are the 3 possible origins of cementum?
Pulp cells
HERS cells
Dental follicle cells
What is the composition of cementum?
65% inorganic material: hydroxyapatite
23% organic collagen
12% water
What nerve and blood supply does cementum have?
It is avascular and no nerve supply
What is a difference between bone and cementum?
Unlike bone, cementum doesn’t remodel
What is a comparison of minerals of enamel, dentine, cementum and bone?
Enamel 95%
Dentine 70%
Cementum 65%
Bone 60%
What is acellular cementum?
It doesn’t have any cells in its matrix
its rate of deposition is slow
Incremental lines are close
precementum layer is thin
What is cellular cementum?
Contain cementocytes within the matrix
The rate of deposition is fast
Incremental lines are far apart
The precementum layer is thick
What do cementocytes occupy?
lacunae
What are the channels for cementocytes called?
Canaliculi
What is extrinsic fibre cementum?
Fibres such as Sharpey’s fibres from the PDL perpendicular to cementum
What are intrinsic fibre cementum?
Fibres produced by cementoblasts
They are parallel to cementum surface
They are found at sites undergoing repair
What is mixed fibre cementum?
Mixture of intrinsic and extrinsic fibre cementum
