BAMS revision Flashcards
1
Q
what is the periodontium?
A
tissues surrounding and supporting the teeth
2
Q
what is the role of the periodontium?
A
- retain the tooth in the socker
- resist masticatory loads
- defensive barrier (protecting tissues against threats from the oral environment)
3
Q
junctional epithelium
A
the physical barrier separating the body tissues from the oral environment
4
Q
where is the only breach in epithelial attachment?
A
where the tooth passes through the epithelium
5
Q
cementum
A
- covers root dentine
- similar in structure to bone (collagen matrix, lamellar arrangement)
6
Q
what are the 2 types of cementum?
A
- cellular
- acellular
7
Q
cellular cementum
A
contains no cells, usually adjacent to dentine, no attached fibres
8
Q
acellular cementum
A
contains cementocytes, present in apical part of root and in furcation regions, collagen fibres from PDL (sharpey’s)
9
Q
where is the weakest point of tooth attachment?
A
apex and furcation regions
10
Q
what forms the inner lining of the tooth socket?
A
cortical plate
layer of compact bond that overlies the spongiosa of the alveolar process on the mandible and maxilla
11
Q
what penetrates the alveolar bone?
A
nutrient canals (volkmans)
12
Q
what is the inner bone of the alveolar bone like?
A
cancellous
contains marrow
13
Q
what happens to the alveolar bone when teeth are lost?
A
the bone is resorbed
leaving a residual ridge
14
Q
what are alveolar canals filled with?
A
blood vessels
15
Q
what is in the connective tissue of periodontal ligament?
A
fibroblasts ECM fibres nerves blood vessels
16
Q
what is in the PDL matrix?
A
hyaluronate GAGs
glycoproteins = fibronectin
proteoglycans
behaves like a viscoelastic gel
17
Q
what are the cells in the PDL?
A
- fibroblasts
- cementoblasts
- osteoclasts and cementoclasts
- epithelial cells (cell rests or debris of
malassez) - defence cells
18
Q
how are cysts formed?
A
lining of cysts created by debris of malassez
epithelial balloon filled with highly protein liquid
19
Q
what 3 types of sensory nerve are in periodontium?
A
- mechanoreceptors (A beta and A delta)
- nociceptors (A delta and C)
- autonomic (sympathetic)
20
Q
mechanoreceptors in periodontium role
A
- rapidly or slowly adapting
- proprioception; chewing control
A beta and A delta fibres
21
Q
nociceptors in periodontium role
A
- protective reflexes
- inhibit jaw elevator motor neurons (popcorn)
A delta and C fibres
22
Q
autonomic (sympathetic) nerves in periodontium role
A
blood vessel control - vasocontriction
23
Q
blood supply of the periodontium
A
- From inferior & superior alveolar arteries, passing into PDL from alveolar bone
- From lingual & palatine arteries supplying gingivae
24
Q
true periodontal ligament
A
fibres connecting tooth to bone at or apical to the alveolar crest
25
'gingival' ligament periodontal fibres
Fibres mainly above the alveolar crest, including ‘free gingival’ fibres
26
purpose of PDL
- Attaches tooth to jaw
- Transmits biting forces to alveolar bone
Organised connective tissue
Width approx = 0.2 mm
27
fibres in PDL
Collagen = (types I & III)
- Principal fibres - true periodontal ligament
- Support tooth; load bearing
Oxytalan fibres
- Function uncertain
28
alveolodental fibre types (5)
- Alveolar crest
- Horizontal
- Oblique
- Apical
- Interradicular (multi rooted teeth)
29
interdental fibres
- Transseptal fibres
* between the cementum of two proximal teeth
- Interdental septum = part of alveolar bone between two teeth
30
gingival fibre groups
- Dento-gingival
- Alveologingival
- Dento-periosteal
- Circular
31
gingival fibre groups role
support the free gingiva
present in the lamina propria in marginal gingivae
32
'gingival margin'
where the gingiva meets the tooth
33
muco-gingival margin
where the ginigiva meets the mucosa
34
junctional epithelium type
stratified non-keratinising epithelium
35
junctional epithelium special properties
2 basal laminas
- One faces tooth (internal)
- One faces connective tissue (external)
36
how does the junctional epithelium and epithelia attach?
- Internal basal lamina & hemidesmosomes
| Connects the junctional epithelium to tooth surface
37
interdental epithelium type
stratified squamous (keratinised)
38
what type of forces are PDL mainly subjected to?
intrusive forces and rarely extrusive and horizontal forces
39
cells in dental pulp
- Odontoblasts
- Fibroblasts
- Defence cells
40
extracellular components of dental pulp
Fibres
- Collagen
- Oxytalan
Matrix
- Proteoglycans
- Chondroitin SO4
- Dermatan SO4
41
nerves in dental pulp
- Sensory
| - Autonomic (sympathetic)
42
what makes up the dental pulp?
- cells
- exracellular components
- nerves
- blood vessels
- lymphatics
43
what is in the cell rich zone?
fibroblasts
44
functions of dental pulp
- Nutritive - blood vessels
- Dentine growth (primary + secondary)
- Dentine repair (tertiary)
- Defence (immune cells; lymphatics)
- Neural (sensory - pain… control of dentinogenesis)
45
what does both the dentin and pulp develop from?
dental papilla
46
structural links between the dentine and pulp
Pulpal elements extend into dentine
- Odontoblast processes
- Nerve terminals
- Immune cells (dendritic cells)
- Dentinal fluid
NB** no blood vessels in normal dentine
47
primary dentine
rapid formation
from ADJ --> till full tooth formed
48
secondary dentine
slower
continues to be made and laid down throughout life
reason why pulp shrinks over lifetime
49
haemodynamics and hydrodynamics of pulp
Fluid leaks from pulp capillaries - interstitial space
- Some drain by lymphatics
- Some pass along dentine tubules (dentinal fluid)
50
reactionary dentine
- in response to mild stimulus
- laid down by primary odontoblasts
secreted by original odontoblasts
51
reparative dentine
- in response to intense stimulus that destroys primary odontoblasts
formed by odontoblast-like cells (secondary odontoblasts)
52
abarsion due to
mastication
53
attrition due to
bruxism
54
abfraction due to
occlusal overload (fractions and cervical lesions)
55
erosion due to
diet, gastric reflux, vomitting
56
what does the odontoblast layer act as?
permeability barrier
- Separates pulp and tubular space
- Regulates movement of material between pulp and tubular extracellular fluid
- Movement may be in either direction
57
what moves from the pulp to the dentine?
- nutrients to sustain the cell
- formation of 2 + 3 dentine
- function of tubular nerves (e.g. K+)
58
what moves from dentine to pulp?
- medicaments applied to dentine
| - diffusion of toxins, from bacteria, components of filling materials
59
anatomy of pulp nerves
Branches of the alveolar nerves
Neurovascular bundles enter pulp via apical foramen and pass along root canal in centre of pulp towards the coronal pulp chamber
- Branches fan out in subodontoblastic layer; some nerves enter dentinal tubules
60
innervation of dentine
some nerves enter tubules
- Under cusps : 40% of tubules contain nerve
- Some axons extend 100-200um
Tubular innervation is less in coronal dentine (15%) and root dentine (4%)
- Few axons enter tubles; most end in pulp-predentine region
61
what stimuli can bypass the hydrodynamic mechanism?
act directly on intradental nerves
- intense heating
- intense cooling
- electrical current
- pain-producing chemicals
62
how can high fillings cause dentine pain?
force distorts the dentine and alters the tubular fluid flow
63
intradental nerves are...
A beta and delta (large and small myelinated)
C fibres (unmyelinated)
64
What activates A beta and A delta fibres in intradental nerves?
hydrodynamic stimuli applied to dentine
probably mediate 'normal' dentinal sensitivity
65
What activates C fibres in intradental nerves?
directly by stimulu, rather than hydrodynamic mechanism
- respond to most forms of intense stimulation
probably mediate pain associated with pulp inflamttion (e.g. caries)
66
4 things that control pulpal blood flow
Local factors e.g. metabolites
Nerves
- Sympathetic
- Somatic afferents
Circulating hormones e.g. adrenaline
Drugs
- E.g. local anaesthetic preparations with vasoconstrictors
67
5 functions of pulp nerves
Sensory - mediating pain
Control of pulp blood vessels
- Sympathetic : vasoconstrictor
- Afferents : vasodilator (axon reflex)
Promote neurogenic inflammation
Neuropeptides : subset P, CGRP
Promote dentine formation
68
dentine-pulp first response to injury
immediate, nociceptor activation (pain)
69
dentine-pulp response to injury after 1 min.
- early inflammatory response
- kinins, prostaglandins, neuropeptides
- vasodilatioin
70
dentine-pulp response to injury after 10 mins
- nociceptor sensitisation
- extravasation of fluid, odema
- polymorph migration
71
dentine-pulp response to injury after 100mins
- enzyme activation; nerve growth factor
| - monocyte presence
72
dentine-pulp response to injury after 1 day
- nerve spouting (NGF)
- increased axonal transport
- altered excitability of CNS synapses
73
dentine-pulp response to injury after 1 week
- repair tertiary dentine formation
74
pulpitis
Acute inflammation in the pulp
- Pulp cannot swell as it is confined within the pulp chamber
Odema causes increase in pulp pressure
- Can have variable effects on blood flow + nerve excitability
75
what enamel is more mineralised and harder?
surface enamel is more mineralised and harder than deeper enamel
76
how does enamel hardness decrease
decrease in hardness from cusp tip to cervical margin
mineral structure varies too
77
what is a basic unit of enamel?
rod/prism
78
enamel rods run
from ADJ to surface
79
enamel rod dimensions
5um x 2.5mm
80
long parallel enamel rods are due to
daily growth (approx. 4um)
cross sections in rods
81
brown transverse stiae are due to
weekly intervals
25-35um apart
82
does rod orientation effect demineralisation?
yes
distinction in head and tail regions is cause by variations in orientations of HA in different parts of the rod
83
HA content in enamel
95% weight
| 90% volume
84
Water content in enamel
4% weight
| 5-10% volume
85
organic matrix content in enamel
1% weight
(1-2% volume)
Proteins : amelogenins; enamelins; peptides; amino acids
86
what does the organic compound of enamel regulate?
the nanomechanical properties of enamel = FLEXIBILITY
87
how are crystallites deposited?
at right angles to the ameloblast membrane
88
where are HA crystallites largest?
in enamel, compared to dentine, cementum and bone
89
ground section of tooth shows
mineral present
| no soft tissues
90
decalcified sections of tooth shows
no mineral
| just soft tissues
91
how to enamel rods run?
in a sinusoidal course
92
what causes banding patterns (Hunter-Schreger bands) in enamel?
periodic orientation
93
hunter-shreger bands
- Rod periodic orientation
| - Absent in outer enamel
94
gnarled enamel can be found at
cusps
95
incremental lines in enamel are
brown striae of retzius
96
enamel tufts at the ADJ are
hypomineralised regions due to residual matrix protein prism boundaries
97
enamel lamella at ADJ are
incomplete maturation of groups of prims
| - fault line extending through enamel thickness
98
enamel spindles at ADJ are
odontoblast processes extending into the enamel
