Periodontal Ligament Flashcards
(151 cards)
1
Q
what kind of tissue are cementum and alveolar bone
A
hard tissues
2
Q
what connects the cementum and alveolar bone
A
periodontal ligament
3
Q
what does the periodontal ligament connect
A
cementum and alveolar bone
4
Q
what are the main cells found in connective tissues
A
fibroblasts
5
Q
what is the periodontal ligament innervated with and why
A
nerves and blood vessels in order to provide information
6
Q
what branch of the nervous system controls blood vessels
A
sympathetic
7
Q
what is found within the periodontal ligament matrix
A
- glycoproteins
- proteoglycans
- hyaluronate glycosaminoglycans
8
Q
what are glycoproteins
A
proteins that have sugars on their side
9
Q
what are proteoglycans
A
proteins with the core made of sugar and the side made of protein
10
Q
what is hyluronate glycosaminoglycan
A
a special type of glycan
11
Q
why is it important that there are proteins in the matrix of periodontal ligaments
A
the matrix can be affected by periodontal disease, and the property of the matrix proteins is to behave as a viscous elastic gel which is important for the ligament
12
Q
what are the cells that are found in periodontal ligament
A
- cementoblasts
- fibroblasts
- osteoclasts and cementoclasts
- epithelial cells
- defence cells
13
Q
what do cementoblasts do
A
synthesise cementum
14
Q
why are there cementoclasts and osteoclasts in the periodontal ligament
A
to destroy alveolar bone and cementum
15
Q
why are there epithelial cells in the periodontal ligament
A
the root is formed by epithelial cells, and once the root is formed they do not have a use and will remain there and become cell rests of malassex.
16
Q
what are the sensorial nerves in the periodontal ligament
A
mechanoreceptors and the nociceptors
17
Q
what are nociceptors important for in the periodontal ligament
A
reflexes like jaw movement
18
Q
what is the purpose of sympathetic innervation of the periodontal ligament
A
control of blood flow thorugh vascoconstriction
19
Q
what is the main vasoconstrictor used in local anaesthetic when doing procedures to reduce blood flow
A
adrenaline
20
Q
what groups are periodontal fibres subdivided into
A
true periodontal ligament and the gingival ligament
21
Q
what does the gingival ligament connect
A
soft tissue to hard tissue
22
Q
what is the periodontal ligament
A
an ordanised connective tissue - it has the order of what things are and what things do.
23
Q
what is the periodontal space
A
this is the width of the periodontal ligament and is very thin. the space depends on the health of the patient
24
Q
what is ankylosis
A
whenthe tooth is attached to the bone and does not have any periodontal ligament there
25
what reflex is in place to prevent fracturing from the force of biting
the jaw jerk reflex which is responsible for the protection of teeth when biting. sensitivity for this reflex are the nociceptors found in the periodontal ligament
26
what is the alveolo dental ligament
the connective from cementum to bone
27
what can affect the speed and force of chewing
the consistency of food
28
how does the arrangement of periodontal ligament fibre groups differ
depending on their function
29
what is the function of periodontal fibres
provide resistance for movement
30
what is the function of the matrix
provide a cushion
31
are the forces on teeth linear
no they are applied through the fibres
32
where are the fibres found
alveolar crest near the gingiva, horizontal, mid of the tooth and the apex of the tooth
33
what are the different fibre groups
oblique, apical, horizontal, alveolar crest
34
what does periodontitis affect
the fibres and how they stretch as well as the viscous elasticity of the matrix.
35
what are the targets for treating periodontitis
periodontal fibres and how they stretch as well as the viscous elasticity of the matrix
36
what fibres connect cementum to cementum
interdental ligament fibres
37
how does movement get transferred to teeth
the movement is delayed rather than being directly transferred to the teeth, which reduces the forces. the periodontal ligament therefore reduces the forces as the bone is not supposed to receive the movement
38
how is force detection differed by dentures
there is no periodontal fibre so the forces transmitted are not recognised. the gingiva can give some recognition but not a lot. therefore implants are better as there are more forces being detected, however there is still loss of mechanoreceptors and nociceptors.
39
describe the features of periodontal ligament
- non mineralised connective tissue
- highly vascularised and innervated
- reacts to orthodontic loads
40
what do the mechanoreceptors do in the periodontal ligament
they convey sensory information to the brainstem and the trigeminal nerve
41
what are the fetal like properties of the peridontal ligament
high turnover of the extracellular matrix and a high proportion of type III collagen
42
what does the peridontal ligament occupy
the space between the root of the tooth and the alveolar bone
43
what is the periodontal ligament derived from
dental follicle
44
when is the continuity of the periodontal ligament with the gingiva important to consider
when considering the progression of periodontitis
45
what is the periodontal ligament continuous with
the gingiva
46
how does the width of the periodontal space differ
by the health of the tooth but also the region. narrower in the mid root region
47
when is periodontal space increased
when teeth are subjected to heavy occlusal stress
48
what is tooth ankylosis
the tooth fuses to the alveolar bone.
49
what suggests the presence of signalling systems that maintain the periodontal space
the fact that alveolar bone rarely ever colonises the periodontal space - how does it know to do this
50
what are the main functions of the periodontal ligament
- resisting displacement forces and protecting the dental tissues from damage by excessive occlusal loads
- responsible for the mechanisms where a tooth attains and maintains a functional position.
- maintain and repair both alveolar bone and cementum
- neurological controls of mastication due to the presence of mechanoreceptors
51
what makes up the majority of periodontal fibres
collagenous fibres - roughly 90% of all periodontal ligament fibres
52
break down the collagenous fibre components of the periodontal ligament
70% is type 1 collagen
20% is type 3 collagen
much of the collagen is gathered to form bundles called principle fibres that appear to be more numerous at their attachments to cementum than at alveolar bone. cellular processes surround the fibre bundles
53
what surround the principle fibres
cellular processes
54
what are principle fibres
bundles of collagen fibres
55
where are principle fibres found to be more numerous
their attachments to cementum
56
what is the major protein component of most connective tissue
type I collagen
57
what is type III collagen associated with
rapid turnover
58
is type III collagen localised at a specific region of the peridontal ligament, and if so where
no it is not
59
how do the orientations of principle fibres differ
depending on the region of the periodontal ligament.
60
are there specific functions for each group of the principle fibres
no
61
what are the different regional names for the principle collagen fibre bundles
- dentoalveolar crest fibres
- horizontal fibres
- oblique fibres
- apical fibres
62
describe the course that principle fibres take as they pass from the region of the alveolar bone to the tooth
not a straight course - said to be wavy (it is not known whether the waviness is real or an artefact of histological preparation)
63
what are fibroblasts responsible for
the synthesis and degradation of collagen
64
what can be found within each collagen bundle
subunits of structure called collagen fibrils.
65
how are collagen fibrils formed
the packing together of individual tropocollagen molecules
66
what does the diameter of collagen fibrils reflect
the mechanial demands put upon the connective tissue
67
what are sharpeys fibres
principle fibres of the periodontal ligament that are embedded into the cementum and the bone lining of the tooth socket
68
where are the sharpeys fibres most numerous
at the attachments into cementum. they are also smaller here
69
describe the rate of turnover of collagen within the periodontal ligament
faster than virtually all other connective tissues.
70
how does the rate of turnover differ within the periodontal ligament
varies in different parts of the same tooth. highest toward the root apex.
71
why may there be a high rate of turnover in periodontal ligament
could relate to the functional demands placed upon the tooth in terms of remodelling as a reaction to occlusal stress and to tooth movements
72
what are elastic system fibres composed of
elastin, elaunin and oxytalin fibres
73
which elastic fibres are found in human periodontal ligament
elaunin and oxytalin
74
what is oxytalin
immature elastin fibres with elastin and collagen components
75
what are oxytalin fibres attached to
the cementum of the tooth and the course out through the periodontal ligament in various directions.
76
are oxytalin fibres incorporated into the bone
only rarely
77
how can oxytalin fibres be recognised
as a collection of unbanded fibrils arranged parallel to the long axis of the fibre
78
do oxytalin fibres change with age or with masticatory loading
neither
79
what is reticulin
argyrophilic - known to be type III collagen. the reticular fibres crosslink and form a fine meshwork to aid tissue support. they are also related to basement membranes within the periodontal ligament
80
what are the rests of malassex
epithelial cells found within the periodontal ligament
81
what role do fibroblasts have in relation to teeth
they have an essential role in the adaptive responses to mechanical loading of the tooth
82
what are the features of fibroblasts in periodontal ligament that are not particularly common in fibroblasts of other connective tissues
cilia and many intercellular contacts
83
how do the periodontal fibroblasts and the gingival fibroblasts differ
they are derived from different sources and the gingival fibroblasts are less proliferative
84
what may the information associated with periodontal disease lead to
an increase expression of MMP and aggressive loss of collagen in the periodontal ligament that results in tissue destruction
85
what are cementoblasts
connective tissue cells of the periodontal ligament - cement forming
they are rich in cytoplasm and have large nuclei. they contain all the intracytoplasmic organelles necessary for protein synthesis and secretion
86
what are osteoblasts
bone forming cells lining the tooth socket, resembling cementoblasts. the layer is prominent only when there is active bone formation.
87
where are cementoclasts and osteoclasts found
in areas where bone and cementum are being resorbed
88
what occurs when osteoclasts resorb alveolar bone
the surface of the alveolar bone shows resorption concavities called howship's lacunae, where the osteoclasts lie
89
what are howship's lacunae
resorption cavities on the surface of the alveolar bone following resorption of the bone from osteoclasts
90
what can be found on the part of the osteoclasts that lie adjacent to the bone
a brush border which gives a striated appearance. the border is comprised of many tighly packed microvilli which may be coated with fine, bristle like structures.
91
what are rests of malassez aggregations of
epithelial cell rests
92
how can rests of malassez be distinguised form adjacent fibroblasts
by the close packing of their cuboidal cells and their tendency to stain more deeply
93
what can rests of malassez proliferate to form if stimulated by chronic inflammation
cysts and tumours
94
what have epithelial cell rests been shown to produce
matrix molecles, proteins, growth factors, cytokines and neuropeptides
95
what are the different defence cells of the periodontal ligament
macrophages, mast cells and eosinophils
96
what percentage composition do macrophages make up in the periodontal ligament cell population
about 4%
97
where are the macrophages located within the periodontal ligament
near the nerves and blood vessels
98
what are mast cells associated with
blood vessels
99
which defence cells are associated with blood vessels
macrophages and mast cells
100
what are eosinophils
defence cells occasionally seen in the normal periodontal ligament that are capable of phagocytosis
101
what are dendritic cells
defence cells found in the periodontal ligament that are derived from bone marrow
102
what are the various defence cells of the periodontal ligament capable of synthesising and releasing
bioactive molecules such as cytokines, growth factors, and cell adhesion molecules
103
why must there be replacement cells for when the osteoblasts and cementoblasts of the periodontal ligament become incorporated into the alveolar bone
to permit osteogenesis and cementogenesis
104
is apoptosis a common feature in mature connective tissues of the periodontal ligament
no
105
where is the rich blood supply of the periodontal ligament derived from
the appropriate superior and inferior alveolar arteries. arteries from the gingiva may also be involved
106
where are the arteries that supply the periodontal ligament derived from
a series of perforation arteries passing through the alveolar bone
107
how does the volume of the periodontal ligament occupied by blood vessels vary
between 10 and 30% according to species, tooth type, and whether the tooth is erupted or erupting
108
what forms a capillary plexus
blood vessels found near the root surface
109
where do many of the vessels of the periodontal ligament lie
between principle fibre bundles and close to the wall of the alveolus
110
what is a special feature of the periodontal ligament
presence of large numebrs of fenestrations in the capillaries. this is unusual, as fibrous connective tissue usually has continuous capillaries
111
how do the veins of the periodontal ligament differ from the arteries
the veins do not usually accompany the arteries and instead pass through the alveolar walls into the intraalveolar venous networks
112
how do the junctions between the vascular endothelial cells in the periodontal ligament vary
from close to tight to open. the open junctions are more permeable and provide pathways for fluid and molecular transport. open junctions appear to be characteristic of the venous capillaries in the periodontal ligament
113
what is anastomosis
the connection of blood vessels - in the periodontal ligament the blood vessels connect with the the veins of the gingiva also
114
what are the different nerves found in the periodontal ligament
some are sensory and some are autonomic. sensory are associated with the nociception and mechanoreception. autonomic are associated with supply of the periodontal blood vessels
115
is periodontal ligament more or less innervated than other dense fibrous connective tissue
more
116
how do the nerve fibres enter the periodontal ligament
some enter through the root apex and pass up through the periodontal ligament. others enter the middle and cervical portions of the ligament as finer branches through openings in the alveolar walls
117
are periodontal nerve fibres myelinated or unmyelinated
both
118
which nerve fibres are myelinated
sensory
119
which nerve fibres are unmyelinated
sensory and autonomic
120
what is the function of mechanoreceptors
performing a major role in the transmission of touch and textural information when eating, as well as providig afferent feedback essential in the control of salivation, mastication and swallowing
121
where are rapidly adapting responses seen
from receptors close to the fulcrum of the tooth about which movement is taking place
122
where are slowly adapting responses seen
receptors close to the apex of the tooth
123
what do mechanoreceptors exhibit directional sensitivity in response to
forces applied to the crown of the tooth, which can be explained by their discrete receptive fields
124
what do the cell bodies of the neurons that innervate the mechanoreceptors in the periodontal tissues mostly lie within
the trigmenial ganglion
125
what is found within the trigeminal ganglion
neurons that respond to mechanical stimulation of the teeth that have been found in the spinal trigeminal nucleus and the main sensory nucleus
126
do the neurons that respond to forces applied to the teeth still exhibit directional sensitivity?
yes, but it may appear to respond to forces over a broader range of stimulus direction
127
what is another role of periodontal mechanoreceptors besides transmission of forces
they modulate the activity of motor neurones of the hypoglossal cranial nerve, helping to control tongue position during mastication
128
what are the pain fibres of the periodontal tissue represented by
fine, unmyelinated fibres terminating as free nerve endings
129
what are neuropeptides released by
sensory nerve endings in the periodontal ligaments
130
what effect can neuropeptides have in the periodontal ligament
widespread effects on blood vessels and cells
131
is it still advantageous to retain tooth fragments and roots if teeth are badly damaged
yes - for sensation
132
why is it important to try reimplantation of teeth
there will be some regeneration of periodontal mechanoreceptors
133
what are features common to both the periodontal ligament and other fetal like connective tissue
high rates of turnover
sharp, unimodel size and frequency distributions of small collagen fibrils
significant amounts of type III collagen
large volumes of ground substance
high content glucuronate rich proteoglycans
presence of pre elastin fibres
high cellularity like the fibroblast like cells possessing numerous intercellular contacts
similar biochemical proprties
134
what are the features of the periodontal ligament that indicate it is a specialised adult connective tissue
- principle collagen fibres have characteristic orientation
- in some species, pre elastin like fibres called oxytalan is present within the periodontal ligament
- rate of turnover is very fast
- cellular and rich in ground substance
- hydrostatic pressure is high
- ligament fibroblasts have features unusual for fibroblasts in adult fibrous connective tissues
- periodontal ligament has cells concerned with the formation of dental tissues
- rich vascular and nerve supply
- capillaries are fenestrated
135
what does the term tooth support mechanism describe
the manner whereby the periodontal ligament resists the axially directed instrusive loads that occur during biting
136
what occurs when there is loading onto the periodontal tissue
the loads are dissipated to the alveolar bone primarily through the oblique principle fibres of the ligament. on release of the load, there is elastic recoil of the tissue which enables the tooth to recover its resting position
137
what is an important clinical consideration for periodontal ligament
chronic inflammatory periodontal disease - toxic products released by dental plaque result in the destruction and loss of periodontal ligament tissue and adjacent alveolar bone
138
what occurs within the periodontal ligament when there is orthodontic loading
wide areas of pressure on one side of the root and corresponding areas of tension on the other side are produced.
- on the side under the tension the periodontal space will become wider where the tooth is drawn away from the alveolar bone following the application of a continuous orthodontic load. bundles of fibres are stretched and the alveolar crest is pulled in the same direction.
- on the side under pressure, the periodontal space becomes narrower and the crest of the alveolar bone is slightly deformed. vascular activity is low.
139
what are the two main functions of oblique periodontal fibres
provide support during biting compression and suspend the tooth
140
how are oblique periodontal fibres inclined
cervically or attached the cementum more apically
141
why are fibres more concentrated on the cementum than the bone
to distribute forces from biting
142
how does staining intensity change on lining mucosa
decreases as you go to the surface
143
what are von ebner salivary glands
minor salivary glands found in the circumvallate papillae on the tongue
144
why is the dorsal surface of the tongue irregular
presence of several types of papillae
145
which surface of the tongue is keratinised
the dorsum
146
where is cellular cementum located on the teeth
furcation regions alongside the apex of the root of the tooth
147
why do the furcations and apex of the tooth have cellular cementum
there is more wear and requires fresh cementum built all the time due to attrition
148
149
when do mechanoreceptors respond maximally
when the area in which they lie is put into tension.
150
what are the nerves found in the periodontal ligament
sensorial nerves
sympathetic nerves
151
what is the issue with the presence of cell rests of malassez
they are the origin of cysts
