dentine and pulp :) Flashcards
describe dentine
forms bulk of crown and root
heterogenous
70%mineralised
vital and sensitive
what detects pressure
proprioceptors in the PDL
what is the first mineralsied tissue to form the tooth
dentine
what is dentine formed from
extraceullar product of the dental papilla
components of the dentine matrix
mainly collagen contains - dentine phosphoproteins - dentine sialoproteins - dentine matrix protine
what happens if dentine sialoproteins or dentine matrix proteins are not present
odontoblasts act more like osteoblasts
secretions are more bone like
What is always adjacent to the odontoblast cell bodies
layer of predentine
what would be seen above mineralised dentine and predentine
mantle dentine
what is dentine calcification initiated by
matrix vesicles
what is the initial mineralisation patterns
spherical calcospherites
what aids mineralisation of dentine
acidic dentine sialoprotiens
what is found within the matrix of mineralising dentine
membrane bound vesicles
what do vesicles in the dentine matrix do
Act as nucleation centres for crystals to form
solution secreted is used for mineralisation
what are the two types of denine
peritubular
circumpupal
describe circumpulpar dentien
tubular with branched odontoblast processes in the dentine; tubule
what do dentine tubules contain and function
extraceilluar fluid fro nutrition and to bathe the odontoblast pricesses
what can the branch processes of the circumpulpal dentine do
lateral branches can communicate
what starts before amelogensis
dentiogesis
what forms the bulk of the dentine
circumpulpal dentine
what Iines the insides of the dentine tubule
peritubular dentine
where can odontoblast processes extend from
from odontoblast cell body to the ADJ
density of the odontoblast processes throughout the dentine
fewer near ADJ
higher density towards the pulp
mineralisation of circumpulpal and peritubular dentine
90 peri
70 circum
colour of dentine
translucent
what can the amount of dentine be used fro
amount of translucent dentine is forensically used to determine the age of individuals
what type of dentine is produced in response to trauma
sclerotic dentine
how is dentine laid down
in increments from the ADJ underlying the incisal edge or cusp tips
how can you see the dentine incremental lines
Uv light with tetracycline (antibiotic)
what antibiotic can be used to see incremental lines and why can it be used
tetracycline
attaches to mineralising tissues
why can tetracycline not be used in those that have developing teeth
brown staining of teeth
glow in the darkq
types of dentine
primary
secondary
tertiary
why are the types of tertiary dentine
reactionary
reparative
when does tertiary dentine occur
extra dentine laid down in response to a threat e.g. caries/trauma
reactionary dentine
existing odontoblasts start to secrete extra dentine in a localised region
reparatie dentine
newly differentiated odontoblasts from pulp-progenitor cell produces dentine
when does primary dentine form
tooth development
when does secondary dentine occur
pulp chamber decreases in size due to mastication/attriction forces on teeth
more dentine produced over timen
what is the dental pulp
repentant of the dental papilla not conveted to dentine
features of the dental pulp
fibrovascualr connective tissue containing nerves and blood vessels
vital and sensitive
will react by inflammation if exposed
where is the cell free zone
underneath odontoblasts in the pulp
contains the sub odontoblastic nerve plexus
what is the pulp stroma
supporting connective tissue
where do odontoblasts lie
dentine pulp juction
what happens after primary dentinogenesis
odontoblasts become quiescent
can be reactivated to produce reactionary dentien
nerves found in the pulp
small myelinated A beta and A delta
unmyelinated C axons
what do the nerves in the pulp transmit
ONLY pain
not heat act
what is a pulpotomy
removing part of the pulp
what is a pulpectomy
removal of the entree pulp
what is endodontics
treatment to the tooth within the tooth
what does removal of the pulp lead to
tooth and dentine non vital
pulp tissue and odontoblasts are removed
what might happen after years after a pulpotomy/pulpectomy
dentine may discolour and show through to enamel
pulp products start to leach through dentine tubules
what is dentine usually covers by
enamel
cementum
how can enamel be exposed
carious lesion through enamel
enamel worn away
gingival recession
how can enamel be worn away
attrition
abarasion
erosion
consequences of gingival recession
exposes cementum
cementum erosion or abrasion
shape of enamel lesiosn
enamel lesion is cone shaped following lines of enamel rods
why is pain in the teeth poorly localised
axon convergence within the teeth and at brainstem
nerves in dentine
very few nerves from the subodontoblastic plexus penetrate into dentinal tubules
only penrtae 1/3 of dentine
Where is dentine the most sensitive
ADJ
Theories for sensitivity in dentine
Nerves in dentine
Odontoblasts act as neurones
Hydrodynamic movement of extracellular fluid in dentine tubules
How to reduce dentine sensitivity
fluoride varnish to harden dentine
use of toothpastes to encourage deposition of peritubular dentine to occlude exposed tubules
How are odontoblast processes shortened
wearing away dentine
cutting cavities
bacterial attack
What does shortening of processes stimuliat
odontoblasts to secrete reactionary dentine
how do amalgam fillings work
mechanically lock in cavity
dentine bonding agents
interlock with dentine matrix
cavity floor decalcified by acid to remove crystals and expose collagen matrix
how are dentine tubules formed
by odontoblast cell processes during development
describe preodontoblasts
cuboidal in shape
become columnar when fully formed
What do odontoblasts secrete before they are fully differentaited
dentine matrix i.e. mantle dentine
less collagen
more ECM
formed thin layer on inner side of future ADJ
describe odontoblasts
columnar polarised cells
nuclei@ basal end
describe mineralisation of dentine and involvement of odontoblasts
unmineralised initially (predentine) odontoblasts move away and produce more predestine odontoblasts retreat into the dental papilla and extend processes dentine forms around the processes (grt tubular structure) dental papilla gets smaller to form pulp
What do odontoblast differentiate from
dental papilla (i.e. fruit part)
What signals induce to
differentiation of dental papilla to odontoblasts and where from
signals from internal dental epithelium of enamel organ
- bone morphogenic proteins
- fibroblast growth factors
- transforming growth factor
when do odontoblasts begin to secrete dentine matrix
before they are fully differentiated
produce mantle dentine to start
what do the matrix vesicles have a high concentration of
phosphatidylserine (high affinity for calcium) Alkaline phosphatase (dentatures calcific poisins)
where does crystallisation start
in matrix vesicles
Process of crystallisation
crystals fine needle like to start
vesicles get bigger as tissue minerlaises
fuse with adjacent calcospherites to produce structure around dentine tubules
what happens if calcospherites fail to fuse
interglobular dentine formed (holly leaf)
how does enamel and cementum mineralisase
no initiation needed
mineralisation is secondary by spread from adjacent dentine
(dentine mineralised by primary calcification initiated by matrix vesicles)
how are enamel spindles fromed
odontoblasts can retreat into a confined area and be trapped
continue to form processes that penetrate between ameloblasts to form enamel spindles
(trapped and cannot go towards DP, enamel deposition starts)
