Dental Hard Tissue Flashcards
What is are the two categories of periodontal tissue?
List 4 dental tissue for each category.
Mineralised/hard: alveolar bone, cementum, dentine, enamel
Non-mineralised/soft: oral mucosa, dental pulp, gingiva, periodontal ligaments
Which one of the 8 types of periodontal tissue can provide stem cells which differentiate into mineralised bone?
PDL
Composition of dentine (in percentages)?
70% Inorganic mineral salts (mainly HA in collagen matrix) + 20% Organic substance (protein)+ 10% H2O
Non-collagenous proteins include… (6)
Non-collagenous proteins include: DSPP, proteoglycans, gla-proteins, acidic proteins, growth factors, lipids
What does DSPP stand for and what is its function (2)?
Dentine sialo phosphoproteins ; Regulates crystal growth and mineralisation of collagen fibres within ECM
What tissue forms the bulk of the teeth?
Dentine
What is the colour of dentine
yellow
Major feature of dentine?
Dentinal Tubules
Dentinal tubules are h…. and have processes of cell bodies (o………).
Hollow
Odontoblasts
What cells stimulate ameloblasts?
Odontoblasts
What makes dentine permeable?
The hollow structure of the tubules within the collagenous matrix
what are Shreger Lines/Primary curvatures?
Sigmoidal/S Shape of dentinal tubules
Where are odontoblast cell bodies located (what junction)? Above or below pre-dentine?
DPJ - dentine-pulp junction
Just below
Function of dentine (4)
- Vital tissue
- Sensitive to stimuli
- Act as “shock absorber”, dissipating large
loads/forces throughout tooth structure; highly
elastic - Formed throughout life of tooth
Hardest to least hardest out of…
- Enamel
- Dentine
- Bone
- Cementum
Enamel
Dentine
Bone and Cementum
3 types of dentine and define each type
Primary= Formed prior to apical completion; more formed rapidly and mineralised than 2nd
Secondary=formed post root completion; more slowly formed and less mineralised than 1st
Tertiary= formed as a result of injury; irregular pattern of tubules and produced by local cells in area of trauma/stimulus
Which type of dentine are circumpulpal, pertiubular, intratubular, mantle dentine from? And define each
Primary Dentine
Peritubular: located in walls of tubules; highly calcified
Intratubular: located between tubules; highly calcified
Mantle: Outermost layer of 1st
Circumpulpal: located around the pulp, uniform structure except around the edges
Which type of dentine makes up the bulk of dentine? (1/2/3 and what specifically)
Primary, circumpulpal
Two types of tertiary dentine and definitions
○ Reactionary: derived from pre-existing dentine
○ Reparative: derives from newly odontoblasts (created pulpal progenitor cells)
Define sclerotic, translucent and dead tracts
- Translucent: caused as of ageing tubules, blocked via peritubular, more pronounced at the root apex
- Sclerotic: occlusion/blocking of tubules caused via external stimulus (similar to translucent but linked with stimulus NOT formed by odontoblasts)
- Dead tracts: odontoblasts killed by external stimulus; leaving hollow tubules which can then be filled with sclerotic. Appear dark under microscope
What are Lines of Von Ebner and are they linked with dentine or enamel?
Dentine Linked
show cyclic activity of odontoblast during dentine formation
What are Schreger Lines (primary curvature) and are they dentine or enamel linked?
Dentine Linked
tubules following sigmoid route
How are dentine and enamel linked?
Dentine must be present for enamel formation; ameloblasts must be present for dentinogenesis to continue
Does enamel harden and mature before or after tooth eruption?
Before
Where is enamel the thickest?
Cuspal/Incisal region
What colour is enamel?
Translucent but it can vary from light yellow to greyish/blue white
What do teeth appear whiter in primary dentition than in permanent dentition?
Primary Dentition has more opaque crystalline form therefore appear whiter than permanent dentition
Why does enamel appear yellower as a person ages?
Enamel gets thinner over time as of wear and so dentine (which is yellow) becomes more visible.
Functions of enamel (4)
Mastication
Aesthetic
Protective
Dissipation of forces
Composition equation of enamel
96-97% Mineral Salts (HA, F-, carbohydrates) + 3-4% Organic substance (fibrillar matrix)
What is the structure of enamel composed of (3)?
They are visible under light microscopes
Enamel Rods (prism) Rod sheaths - Distinct thin layer peripheral to the rods inter-rod substance (cement)
What are Striae of Retzius and are they linked with dentine or enamel?
Enamel linked
Dark lines form DEJ towards surface of tooth, form because of weekly rhythm of enamel production causing structural alteration of rods, 4micrometer intervals
What are Bands of Hunter and Schreger and are they enamel or dentine linked?
Enamel
Optical phenomena caused by changing orientation of adjacent rods
What is gnarled enamel and is it enamel or dentine linked?
Enamel
Are like a geological fault, project from the DEJ for a short distance into the enamel contain greater concentration of enamel than the rest of the enamel
What is perikymata and is it dentine or enamel linked?
Enamel
Enamel lamella, wave like transverse groves, external incremental lines of retzius, project from DEJ for short distance into enamel - No clinical significance
