Tooth Tissues Flashcards
What is the hardest tissue in the body?
Enamel
What is enamel made from?
Ameloblasts produce enamel proteins.
What characteristic of enamel increases with mineralisation?
Transparency.
Where does enamel develop from in the early stages?
Intrauterine glands.
Enamel is formed as a..?
Matrix.
What is Tomes process?
Establishes the crystals in which enamel rods are formed from.
What are enamel rods composed of?
Crystallites.
Enamel is formed outwards from what junction?
The amelo-dentinal junction.
Describe the variations in enamel thickness.
Thicker and more mineralised at the incised edge/occlusal surface, decreases as you approach the cervical margin.
How are enamel rods deposited?
Deposited at right angles to the ameloblast membrane.
What do the rods contain?
Hydroxyapatite crystals.
What makes the Hydroxyapatite crystals more stable?
Replacing the OH with Fluoride.
Name the 2 features of the crystallite structure.
Head and tail.
Hydroxyapatite makes up what percentage of the enamel weight?
95%
Water makes up what percentage of the enamel weight?
4%
The organic matrix makes up what percentage of the enamel weight?
1%
What happens to a tooth if the water is removed?
Becomes extremely brittle.
Dentine is the supporting tissue beneath..
Enamel.
Why is dentine permeable?
It contains dentinal tubules.
What colour is dentine?
Yellow(ish)
Where is dentine thickest?
In the areas that receive the greatest force.
Hydroxyapatite makes up what percentage of the dentine weight?
70%
Water makes up what percentage of the dentine weight?
10%
Organic matrix makes up what percentage of the dentine weight?
20%
When is primary dentine present?
When the tooth is forming.
When is secondary dentine present?
Once the tooth has been formed.
When is tertiary dentine present?
In repair.
What direction does dentine grow in?
Inwards.
What shape is primary dentine?
‘S’ shape
What shape is secondary dentine?
Wavy shape.
Describe the relationship between caries and the dentinal tubules.
Caries follow the shape of the tubules inside the tooth and can affect the deeper layers.
What processes from the pulp extend into dentine?
Odontoblast projections.
Where is the dental pulp and dentine formed?
The dental papilla.
The pulp is..
Vascular and innervated with unmyelinated nerve ending)
What does the pulp mainly consists of? What is its function?
Odontoblasts. Produce dentine.
Describe blood vessels in relation to dentine.
Blood vessels are close to dentine but never embedded in the dentine.
What is the purpose of cementum?
Covers root dentine
What does cementum provide attachment for?
The periodontal fibres
Name the 2 types of cementum.
Cellular and Acellular.
What is the first cementum to be formed?
Acellular cementum
What cementum contains Sharpey fibres?
Acellular cementum
What is the function of the sharpey fibres?
Attach the tooth to the alveolar bone.
What cells does the cellular cementum contain?
Cementocytes.
Where is cellular cementum found?
At the apical parts of the root and furcations.
Name the 3 ways the cementum sits in relation to dentine.
Touch, overlap or expose the dentine.
What type of fibre cementum are sharpey fibres?
Acellular extrinsic fibres.
What does cellular intrinsic fibre cementum lack?
Sharpey’s fibres
What does cellular intrinsic fibre cementum not have a role in?
Tooth attachment
What is the rule in relation to fibres and cellular tissue.
The more cellular the tissue the less fibres are present.
What is the function of the periodontal ligament?
Transfers biting forces to the bone.
What cells are present in the periodontal ligament?
Fibroblasts, cementoblasts, osteoclasts and debris of malassez.
What sensory cells are present in the periodontal ligament?
Nociceptors: Initiates reflex to protect teeth.
Mechanoreceptors: Detect the pressure on teeth.
What are true periodontal fibres?
Connects tooth to the bone
What is the gingival ligament?
Connective tissue that provides support to the fibres.
Name the principal fibre groups of the periodontal ligament.
Alveolar crest: (Similar to horizontal)
Horizontal: Limits lateral movement and rotation
Oblique: Resist vertical and intrusive movement.
Apical: Provides cushioning.
Inter-radicular: Found between the roots of multi-rooted teeth.
What is the purpose of trans-septal fibres? Why are these fibres unique?
Keep teeth aligned. Do not have and osseous attachment.
