Tooth And Periodontal Anatomy Flashcards
1
Q
What is tooth sensibility and tooth vitality
A
- Tooth sensibility is its in tact nerve supply
- tooth vitality is its blood supply
2
Q
where do roots generally lie on molars?
A
mesiobuccally
Upper: 2 buccal 1 palatal
Lower: 1 distal 1 mesial
3
Q
what were the lines of defence of the root of a tooth to bacteria
A
-cementum surrounds all of the porous dentine until the apex (also stops bacteria and toxins exiting the pulp)
-pulp can deposit tertiary dentine to move pulp from infection
-pulp contains immune cells
-periapex acts as 2nd line defence
-
4
Q
how wide should the periodontal ligament space be
A
0.2-0.3mm
5
Q
the PDL space sits between cementum and….
A
lamina dura
6
Q
what abnormalities can happen through tooth formation (3)
A
gemination - tooth attempts to split
fusion - 2 tooth (crown) germs adjacent fuse together
concretence- roots of adjacent teeth fuse via cementum
7
Q
what is gemination
A
where a tooth attempts to split in 2
8
Q
what is fusion of teeth
A
where adjacent tooth germs fuse (crown)
9
Q
what is concretence
A
where the roots of adjacent teeth fuse at the cementum
10
Q
what is ‘dens in dente’
A
infolding of the outer dental material into the interior tooth
11
Q
what is dilaceration of a tooth
A
a sharp near 90 degree bend in the root or crown due to trauma
12
Q
what is Taurodontism
A
elarged pulp chambers
very low furcation
short roots
(cow teeth)
13
Q
describe the characteristics of amelogenesis and causation
A
very thin, grooved and pitted enamel that is discoloured and flakes off
due to defects in amelogenin gene
14
Q
describe the characteristics of dentinogenesis and causation
A
small, soft, thin dentine with enlarged crowns/pulps and short roots
pulpal obliteration
hand in hand with osteogenesis imperfecta
15
Q
what is pulpal obliteration
A
hard deposits in pulp chamber remove contents of pulp and replace with hard tissue - dentine
16
Q
what are odontomas and when are they most likely
A
technically begin tumours
derived from odontogenic epithelium and produce tooth-like tissue around forming teeth
incidence 10-20 years old
17
Q
when do odontomas cause problems
A
Benign tumors of the bone
Eruption of secondary dentition
18
Q
what types of odontoma can you get and where do they commonly occur
A
compound: large single mass of radiopaque tooth tissue (posterior mandible)
complex: lots of small denticles in a capsule and often occurs in the anterior maxilla
19
Q
when do odontomas stop devloping
A
when causative tooth stops devloping
20
Q
what is ICP
A
intercausal position - the position of the mandible where there is maximum intercuspation
21
Q
if a patient has an over-erupted tooth, what are some causes of this
A
no opposing teeth
opposing tooth has under contoured restoration
Periapical abscess
22
Q
if a restoration has fallen out and there are no signs of recurrent caries, what is the likely cause of the failure of restoration?
A
poor occlusion with the restoration increased pressure on tooth
23
Q
what is CR
A
centric relation
Relation of the mandible to the maxilla when the condyles are seated in the midmost uppermost position in the glenoid fossa
It is a jaw position and has nothing to do with the teeth
It allows a range of movement ~25mm - when the condyles are fully seated in the glenoid fossa- This is a hinge movement
24
Q
how far can we open out mouth before we leave CR
A
~25 mm
25
what is RCP
retruded contact position
The relation of the mandible to the maxilla when there is first contact between teeth whilst the mandible is in the glenoid fossa i./e in centric relation
26
where do we usually find RCP?
on a posterior teeth, usually on just one side
27
how do we find a patients RCP
ask them to put their tongue as far back along their palate
| close their teeth very slowly until in contact
28
how do we find a patients ICP
ask them to put their tongue as far back along their palate as possible
close down
29
what is protrusive excursion and how do we make a patient do this
this is where the mandible moves forward from ICP and up against the maxilla bringing the lower incisors infront of the upper incisors
30
what controls and affects protrusive excursion
the protrusive guidance (teeth involved)
| the incisor classification controls this
31
what is class I occlusion
ideal
| where incisors have ideal angulation and the lower incisal edge sits on upper incisal cingulum plateau
32
what is class II occlusion
where the angle of the upper incisors is not ideal
division 1 - proclined
division 2 - reclined
33
what is class III occlusion
where the lower anterior are proclined leading to the lower anterior being in front of the upper anterior in ICP
34
where do we measure the classification of occlusion
in ICP
35
how does Class II div 1 and 2 affect protrusive excursion
div 1 - shallower and longer, maybe posterior teeth involved
| div 2 - steeper and shorter,
36
what occlusal class has negative overbite?
III
37
in class III occlusion, where does protrusive guidance occur
posterior teeth
38
what are the two classes of guidance for lateral excursion
canine guidance
| group function
39
what is the jaw split up into during lateral excursion
working side - side jaw is moving towards
| non-working side - side jaw is moving away from
40
how do we find a patients lateral guidence
into ICP
keeping teeth together, move teeth to the working side
observe which teeth are in contact - guidance either canine or group function
41
which guidance for lateral excursion is ideal and why
canine guidance
long roots
bulbous crown
circular roots to take sideways force
42
what are non-working side contacts known as during lateral excursion
interferences
| cause failed restorations and fractures
43
what teeth should separate during excursions
protrusive excursion - posterior teeth
| lateral excursion - non-working side teeth
44
how do we take an occlusal assessment
1. ICP contacts
2. RCP contacts
3. Slide from RCP to ICP
4. Anterior guidance teeth
5. Lateral excursion teeth
45
what is horsehsoe articulating paper used for
only used for dentures
| too thick and uncomfortable
46
what are some disadvantages of horseshoe articulating paper
too thick and uncomfortable
| so thick that it can fill gaps in occlusion and make it seem as though there is occlusion where really there is a gap
47
what should we use to check normal occlusion of most restorations and occlusions and when should we not use it
regular articulating paper
| don't use for detailed occlusal assessments (GHM paper) or dentures (horseshoe)
48
what is GHM paper and when is it used
very accurate articulating paper
19 microns thick
Used for occlusal assessment
49
what is the thinnest occlusal assessing material
Shimstock foil 8 microns thick
50
how do we use shimshock
place it in between teeth - try pull it out
51
how do we measure RCP contacts
Help patients into CR by putting fingers on the lower border of the mandible and thumbs on chin, allow patients to relax and move their jaw up and down until moving on the hinge, then slowly bring into occlusion to first contact.
52
how do we measure the slide from RCP into ICP
large or small slide
53
what is crossover interference
during extreme protrusive excursions, the lower teeth interfere with the upper teeth
54
what do we measure and report when investigating protrusive excursion
which teeth are involved with GHM or shim stock
any posterior disocclusion - posterior teeth contacts during protrusion
any crossover interference - extreme protrusion causing lower teeth to meet upper
55
what do we assess during lateral excursion assessment (2) and how
any non-working side occlusion
canine or group function
mark guidance with GHM or shimstock
56
what occlusal checks do we make during restorations
BEFORE:
- check involvement in occlusal positions
- check involvement in guidance's
AFTER:
-check that we have maintained the occlusions
57
if we have a fractured restoration that was previously guiding, how do we restore this tooth in terms of its occlusion and why
provide restoration
ensure it has little/no involvement in guidance as this obviously put too much stress on the restoration
ensure it is still involved in ICP as if not, the opposing tooth will over-erupt
58
what should we consider when changing occlusion due to failed restoration
if we remove contact during excursion for example, this may put extra stress on another guiding tooth causing more fractures
59
what is pulp vitality
presence of a blood supply to the dental pulp (tooth is alive and cells are alive)
60
what is pulp sensibility
ability of the A delta fibres in the dental pulp to respond to a stimulus (nerve supply)
61
when may a patient have vitality but not sensibility
trauma
62
why are vitality tests better than sensibility tests
nerve supply can be disrupted leading to false negatives
| blood supply cannot be disrupted without the tooth dying so it is most reliability for the life of tooth
63
what are 2 common sensibility tests
cold ethyl chloride test
| electric pulp testing
64
what are common vitality tests
laser doppler flowmetry and pulse oximetry
65
do we generally do vitality or sensibility testing
sensibility as we assume if there is a nerve supply, there is also a blood supply
also much cheaper and requires less expensive equiptment
66
where is the best place to place an ethyl chloride cotton wool bud
mid-labial (mid buccal) surface as this is most sensitive to tests
67
what must we do when doing a cold sensibility test
test mid-labial surface for 15 seconds or until stimulated
| test contralateral teeth to compare and see if negatives are due to enamel thickness
68
if we get a negative or uncertain positive cold test, what do we do next
electric pulp test
69
how much bone surrounds roots of permanent molars
1cm
70
where is the most permeable surface of molar roots
mesial and distal surfaces
71
what are the weekly stages of extraction pocket healing
immediate blood clotting, vasodilation, WBC
week 1: granulation tissue, neutrophils on top, bone resorption, epithelium proliferation
week 2: major epithelial growth to continuity, granulation maturation and osteoid formation
week 4: new bone formation
3 month : bone maturation
72
what is ankylosis
where root of tooth is fused with alveola bone via cementum with reduced PDL space
73
What are the tooth's pain nerve fibres
A delta fibres
74
if enamel is unsupported, what does this mean
reduced dentine underneath it so can fracture under pressure
75
what is undercut
the distance between the largest bulbosity of the tooth and the depth of the sulcus below it
76
where and when do patients get 'flabby ridges'
if they have natural teeth against an edentulous area
| often in anterior 1/4 of mouth
77
what is embrasure
V shaped valley between adjacent teeth
| can be occlusal, lingual/palatal or buccal
78
Average length of maxillary and mandibular canines?
Maxillary 26.5mm
| Mandibular 25.5mm
79
what is the % structure of enamel
96% mineralized inorganic hydroxyapatite
1% organic
3% water
80
describe the inorganic structure of enamel
hexagonal hydroxyapatite crystals rods 6 micrometres in diameter
perpendicular to tooth surface
81
what is the average depth of enamel
2mm
82
What are some characteristics of healthy gingiva
Knife edge margins
Stippled
Presence of papilla
No bleeding
83
where should the junctional epithelium attach and what are its healthy characteristics
at the CEJ cemento-enamel junction
| smooth and attached to PDL below
84
how deep should the sulcus depth be around a healthy tooth
0.5-2mm
85
what is the function of the JE
apply constant microbial challenge being porous allows GCF to defend against bacteria to recruit neutrophils
produce antimicrobial chemicals
high turnover leads to epithelial cells funnel towards sulcus preventing colonization
attach underlying PDL to the tooth enamel
86
what is the most common enamel matrix protein
amelogenin
87
what is molar-incisor hypo mineralization and what implications does this have
where we have more porous, less mineralised first molars and first incisors
more sensative to brush and more suspetable to decay and TSL
88
what happens to the apex of a tooth as we age from young to adulthood
it goes from very wide, close to nearly closed allowing small blood vessels and nerves
89
how is the JE attached to underlying connective tissue and enamel
hemidesmosomes
90
what are some charatceristics of JE
flattened cells connected with hemidesmosomes to connective tissue and enamel
large intracellular space making porous
very rapid turnover
91
what are some unfavourable characteristics of the pulp chamber
tight apical constriction : blood and lymph flow limited and easily disrupted, intrapulpal pressure
unyielding walls : limiting volume to accommodate pulp swelling = pain
surrounded by bone = infection often leads to bone loss
92
what is the function of the dental pulp
```
Allows for root development in immature teeth.
Maintain lifelong tooth development.
Maintains desirable properties of dentine (elasticity) by supplying nutrition to the organic components of dentine.
Sensory function (nociception) – warning system
Maintain a defensive/protective role against dental caries, trauma, TSL
```
93
which pain receptors are found in the pulp and what are they responsible for
A delta fibres - sharp pain - found at peripheries (first to stimulate)
C fibres = dull pain - found centrally, deeper
94
what types (and percentages of) collagen are in bone matrix
collagen I = 95%
| collagen V = 5%
95
explain the structure of bone
collagenous bone matrix (95% collagen I, 5% collagen V)
between fibres we find small uniform crystals of hydroxyapatite
Small amounts of non-collagenous proteins, some which are unique to calcified tissue (e.g. osteocalcin).
within bone we find adipose tissue - bone marrow
96
what cells are found in bone
Osteoclast (Oc): Large multinucleated cells. Bone resorbing cells.
Osteoblast (Ob): Bone forming cells.
Osteocyte: Originate from osteoblasts which have become embedded in the bone matrix. Involved in sensing mechanical loads and Ca2+ homeostasis.
Bone lining cells. Originate from osteoblasts. Line quiescent periosteal and endosteal surfaces of bone .
Osteoprogenitor cells (stromal cells). Precursors of osteoblastic lineage. Mesenchymal stem cells are found in the bone marrow.
97
what is the function and fate of osteoblasts (3)
deposit bone during remodelling and bone growth. eventually turn into:
bone lining cells = Line quiescent periosteal and endosteal surfaces of bone .
osteocytes = become embedded in the bone matrix. Involved in sensing mechanical loads and Ca2+ homeostasis.
98
compare the structure of primary and reactionary dentine
organised parallel dentinal tubules in 1
| disorganised dentinal tubules in 3
99
describe the structure of the pulp-dentine interface
```
dentine
predentine
odontoblast
cell free zone
cell rich zone
pulp
```
100
explain the structure of odontoblasts and associated structure and their function
single cuboidal cells that line inside of pulp chamber
large thin odontoblast cell processes that invaginate dentine through dentinal tubules
A-delta fibres in close proximity and slightly in tubules to detect stimuli e.g. thermal, pressure
responsible for laying down reactionary dentine
create positive fluid pressure from cell body end preventing toxin/bacterial entry to tubules
101
what cells detect bacteria in dentinal tubules
dendritic cells
102
what cells are found at the dentine/pulp lining (3)
odontoblasts with processes
dendritic cells for immune response to stimuli
A delta nerve fibres to detect painful stimuli
103
what is the function of odontoblast processess
form peritubular dentine and form dentinal tubules for innervation of tooth
104
what are the 2 types of tertiary dentine and compare
reactionary dentine : primary odontoblasts secrete dentine in a very similar structure to primary dentine to distance pulpal chamber from incoming infection and bacteria - mild stimulus
reparative dentine: primary odontoblasts die, secondary odontoblasts organise at site and place dentine. Structure depends on how well odontoblasts organise and speed of deposition - stronger stimulus
105
the faster reparative dentine is deposited...: (3)
The less sensitive to thermal, osmotic,evaporative stimuli
The more porous and impregnated with soft tissue which is prone to infection
Reduced or no tubular fluid
106
in a healthy, non-sclerosed tooth, what temperatures cause pain on contact to enamel
above 45 degrees or below 27 degrees
107
how do we know there must be innervation within dentine and throughout dentine
pain stimulus through temperature is felt before any change in temperature of the pulp due to conduction
dentine sensitivity is constant throughout whole depth of dentine
108
how are odontoblasts innervated and how do we know this
odontoblasts are innervated by A delta fibres
1 nerve innervates 100 odontoblast processes
we know nerves innervate the processes as if we cut the nerve supply, processes shrink and if we re-supply innervation, the processes grow back
109
why must there be other innervation than just odontoblast process fibres
not all processes go to ADJ so A delta fibres cannot innervate to ADJ
however there is sensativity throughout the length of dentine to ADJ
110
what is axonal transport and how does this help us
axonal transport is injecting a fluorescent substance into the trigeminal ganglion
following the fibres and we can see they enter the inner dentine = dentine sensitivity
111
how do we know than dentine permeability affects dentine sensitivity
if we remove the smear layer (layer covering dentinal tubules due to mechanical abrasion) the tooth becomes more porous AND more sensitive therefor permeability and sensitivity are related
112
what is the hydrodynamic theory, explain
Dentinal fluid fills the tubules and is constantly flowing outwards.
If dentine is dried, liquid is taken out of the tubules and odontoblasts are pulled up through the tubules and this causes pain due to stimulation of associated A delta fibres
If liquids are applied with the same osmotic pressure, it doesn't cause any change in the flow of the dentinal fluid
If a solution of sugar is added, this change in concentration will cause pain.
113
what is dentine sensitivity and what causes this
exaggerated, transient response to non noxious stimulus and affects 57% of the population
caused by exposure of dentinal tubules due to a multitude of reasons:
trauma, TSL, caries, gingival recession
114
give 4 reasons why dentine may become exposed
TSL
trauma
caries
gingival recession and cementum breakdown
115
how is the PDL attached to the tooth
PDL fibres - sharpeys fibres
attach into the cementum on root surface
attach into the lamina dura surface of alveolar bone
116
what is the lamina dura and what is another name of this
thin hard layer of bone that lines the socket of a tooth and that appears as a dense white line in radiography
aka - cribriform plate
117
which of the teeth are most likely to have hypomineralization
first molars 6
118
what can cause pitting of teeth
amelogenesis/dentinogenetic imperfecta
hypominerlaization
radiotherapy/chemotherapy
119
how mineralized is cementum, dentine and enamel
```
cementum = 55%
dentine = 65%
enamel = 96%
```
120
what types of cementum do we find
at the top of the root, acellular cementum
| at the apex we find cellular cementum
121
which teeth have 5 cusps
lower 6 - first teeth to erupt at 6 years old
122
on the lower 6, where are the cusps situated
3 buccally getting smaller distaly
| 2 lingually
123
which is the smallest premolar
lower 4 resembles canine with large buccal cusp
124
which is the only anterior teeth with 2 roots
upper 4
125
how many roots do the lower molars have
2 - 1 mesial and 1 distal
126
how many roots do the maxillary molars have
3 - 2 buccal and 1 palatal
