export_chapter 5 dental anatomy Flashcards
(162 cards)
1
Q
What four things does pulp contain?
A
- connective tissue
- nerves
- vaculature
- lymphatics
2
Q
What are the 4 components of pulp connective tissue?
A
- fibroblasts
- thick collagen fibers
- network of fine reticulin cells
- connective tissue cells
3
Q
What can connective tissue cells of pulp do?
A
- differentiate into odontoblasts if stimulated
4
Q
What separates the pulp from dentin?
How does this layer change with age in brachydont teeth?
What does this layer contain?
A
A thin layer of predentin
Gets thinner
Odontoblasts
5
Q
Describe the pulp of a horse at eruption
A
- large common pulp
- primordial pulp surrounding the apex
- primordial pulp is surrounded by thin layer of enamel
6
Q
Describe pulp two years after tooth eruption in horse
A
- dentin and cementum is deposited a root apex
- separate pulp horns develop 1 year after eruption
7
Q
How many pulp horns does each tooth have?
A
- 07-10 have 5
- 06 and mandibular 11 have 6
- maxillary 11 have 7
- incisors have 1
8
Q
How does the hypsodont apical foramen differ from the brachydont apical formen?
Why?
A
- remains relatvely dilated for a prolonged period although does reduce in size with age
- must supply the odontoblasts so they can continue to make secondary dentin to over most of the life of the horse to prevent pulp exposure
9
Q
How do the apical foramen change with time?
A
- become slightly narrower and get displaced occlusaly by continued cementum deposition at apex
10
Q
What did Kirkland find in equine mandibular cheek teeth at 5-8 years of age?
A
- closed apical foramina with two apical foramena in rostral root.
11
Q
How does pulp exposure in hypsodont teeth differ from brachydont teeth?
A
- often can withstand inflammation from pulp exposure due to good blood supply allowing macs and extravasated WBC to control pulpar infection
- odontoblasts can lay down tertiary dentin to seal exposed pulp from healthy pulp
- if not enough odontoblasts, undifferentiated connective tissue cells, or fibroblasts can transform into odontoblasts.
12
Q
What two places is secondary dentin deposited in horse teeth?
What does this result in?
A
- occlusal surface
- pulp horn walls
- narrowed pulp size
13
Q
What is difference in dentin content of teeth in young and old horses and what is consequence?
A
- young horses have high proportion of enamel to dentin, older horses have more dentin vs enamel
- young teeth more prone to shatter during floating, old teeth harder to float
14
Q
What is content of cementum?
A
- 65% inorganic (mostly impure hydroxyappetite crystal)
- 35% organic and water content (makes it flexible)
15
Q
What composes organic part of cementum?
A
- collagen fibers
16
Q
What type of fibers do cementoblasts make?
What type of fibers to fibroblasts make?
A
- small intrinsic fibrils
- large extrinsic fibrils
17
Q
What do the large extrinsic fibrils of cementum make?
A
- sharpey’s fibers
18
Q
What are two types of cementum in horse teeth based on appearance?
A
- regular and irregular
19
Q
Where is regular cementum found?
A
In the peripheral cementum
20
Q
Where is irregular cementum found?
A
- adjacent to the peripheral amelocemental junction
- In the maxillary cheek teeth infundibular cementum
21
Q
Is cementum a live or inert tissue in horse teeth?
A
- live in the subgingival area and a few mm more occlusally b/c has cementoblasts nourished by vasculature of the PDL
- inert on the clinical crown b/c loose blood supply from cementum
22
Q
What is most adaptable of calicified dental tissues? Evidenced by what?
A
- cementum
- ability to respond to infection or trauma by quickly depositing within the alveolus or subgingivally
23
Q
Where is cementum at eruption and how does this change?
A
Entire tooth covered by cementum with infundibular incompletely filled.
Worn away soon after eruption
24
Q
What is function of cementum on all teeth?
On hypsodont teeth?
A
- protect the tooth
- anchor the fibers of the PDL
- strengthen the clinical crown
25
What happens as tooth ages that leads to smooth mouth?
- Teeth worn so only root remains made of dentin and cement so no enamel and wears really quickly
26
What percent of upper cheek teeth had gross caries in the Kilic study?
- 24%
27
What is central infundibular cemental hypoplasia?
| What percent of horses in the Kilic study had this?
- central vascular channels running through the infundibular cement from occlusal surface to variable depth with lateral channels extending as far as the infundibular enamel
- 65%
28
What is junctional cemental hypoplasia?
Where is this commonly found?
Is it clinically signficant?
- Linear areas of cementum hypoplasia in infundibula at enamel junction
- incisor infundibula
- No (incisors hardly ever get caries)
29
What is dentin made of?
- 70% minerals (mostly hydorxyapatite crystals)
| - 30% organic components (collagen and mucospolysaccharides)
30
What causes irregular surface of horse teeth?
| Why is this good?
- Softer dentin and cementum wears away faster than enamel
| - rougher surface, better grinding
31
What are three main types of dentin?
| What are subdivisions?
```
Primary dentin
Secondary dentin (regular and irregular)
Tertiary dentin (reactionary or reparative)
```
32
What is the difference between reactionary dentin and reparative dentin?
- reactionary dentin forms after local insult from original odontoblasts
- reparative froms from newly deifferentiated mesenchymal cells
33
Where does irregular dentin form?
- subocclusally in the center of the pulp cavity (laid down last)
34
What is depth of occlusal secondary dentin in the mandible?
| - maxilla?
- 10.8 mandible
| - 9.0 maxilla
35
What is tooth's initial response to injury, caries, excessive attrition?
- sclerosis of primary dentin tubules
36
What is difference in appearance of dentin in horse tooth and why?
- primary has high levels of heavily mineralized intratubular dentin so is translucent
- secondary is less mineralized and has dull opaque appearance and stains from food pigments so is dark brown
37
Do odontoblasts reach the amelodentinal junction in horses?
Yes
38
Do horses experience pain from odontoblasts reaching the surface?
What is a theory about why?
- most likely not except if damaged (eg reducing larger overgrowths)
- may be calcified
39
Which has higher mineral content-intertubular dentin or intratubular dentin?
What is consequence of this?
- intratubular dentin
| - more resistant to wear
40
What prevents horse teeth from being infected by microorganisms in the patent dental tubules?
- smear layer
| - retrograde flow of fluid in tubules towards occlusal surface
41
Is secondary dentin porous?
| Does it contain odontoblasts?
- no tubules are obliterated
| - no tubules are obliterated
42
Which is more wear resistant regular secondary vs primary?
| Why?
primary
| secondary contains no intratubular dentin
43
Which primary dentin has the lowest intratubular dentin?
| Does it wear faster?
- amelodentinal junction dentin
| - no, protected by the enamel
44
What is most hardest and most dense substance in the body?
- enamel
45
What is mineral content of enamel?
Is it opaque or translucent?
Why?
- 96-98% (hydroxyappetite)
- translucent
- high mineral content
46
What is origin of enamel?
Of cementum?
Of dentin?
- ectoderm
- mesenchyme
- mesenchyme
47
What is organic component of enamel?
- keratin family of proteins
48
What is enamel usually covered by in the horse mouth?
- where are the exceptions to this?
- why does this happen?
- dull, chalky, peripheral cementum
- rostral incisors, occlusally on the cheek teeth
- cementum worn away
49
- is enamel a "living" tissue?
- why or why not?
- what is consequence of this?
- almost dead
- ameloblasts die off as soon as tooth is fully formed
- can't repair itself
50
What are different arrangements of enamel in horse teeth?
- prisms +/- prism sheath
| - less structured interprismatic enamel
51
What are three types of enamel in horse teeth?
- Type 1 - round/oval prisms in parallel rows between flat plates of dense interprismatic enamel
- Type 2 - horseshoe to keyhole prisms with no interprismatic enamel - amelocemental junction
- Type 3 - honeycomb structure of prisms surrounded by interprismatic enamel sometimes present as thin layer at amelodentinal and amelocemental junction
52
What type of enamel is found in the maxillary cheek teeth?
The mandibular cheek teeth?
The incisors?
- More type 1 than 2 (but almost all folds have both)
- Equal type 1 and 2
- Amost all type 2
53
What is orientation of type 1 vs type 2 enamel?
- type 1 45%
| - type 2 various angles
54
How does type 1 enamel resist wear?
| How does type 2 resist wear?
- dense interprismatic plates
| - decussation (interweaving with changes of direction of bundles of enamel prisms that run in 3 dimensions
55
What prevents fine microfractures in cheek teeth enamel?
| Do fractures ever extend into pulp?
- cementum and dentin
| - yes
56
How do donkeys differ from horses?
- maxillary cheek teeth have equal amounts of type 1 and type 2 enamels
57
What are three phases of tooth development?
- initiation
- morphogenic
- cyctodifferentiative
58
Describe the first stage of tooth development (pre-bud stage)
- horseshoe shaped epithelial thickening along the lateral margin of the fetal oral cavity (primary epithelial band)
- this invaginates into the underlying mesenchymal tisse to form two ridges, the vestibular lamina and caudal to it the dental lamina
59
Describe the bud stage of tooth development
- dental lamina produces a serious of epthelial swellings called tooth buds along its buccal margin
60
Describe the cap stage of tooth development
- mesenchymal cells beneath the ectodermal tooth buds proliferated and invaginate into tooth buds
61
What are the cap shaped structures of the cap stage called?
- enamel organs
62
What develop from the enamel organ of the dental laminae?
- all deciduous teeth and the molar teeth.
63
How do permanent incisor teeth, permanent canine teeth, and permanent premolar teeth form?
What is consequence of this related to permanent incisors?
- from lingual/medial extensions of the dental laminae of the deciduous teeth.
- deciduous incisor teeth displaced labially by permanent teeth
64
Describes what happens between the cap and bell stage
- mesenchymal cells proliferate within concave part of the enamel organ and become the dental papilla that eventually ameks dentin and pulp.
- mesenchymal cells extend peripherally to form the dental sac or follicle that surounds the enamel organ and dental papilla until tooth eruption occurs.
65
What is a tooth germ?
- combined enamel organ, dental papilla, dental sac that makes an individual tooth
66
What is the bell stage of tooth development?
- enamel organ proliferates further and forms a concave, bell like shape in brachydont teeth
67
What happens in the bell-like stage of hypsodont teeth?
- incisors and maxillary cheek teeth, invaginations of enamel epithelium that will later become infudibula develop from convex part of the bell into papilla
68
How many invaginations of enamel epithelium form in incisors and maxillary CT?
- one incisors
| - two maxillary CT
69
Where do the cusps of equine CT develop from?
- protrusions on the convex aspect of the bell
70
Where do the peripheral infoldings of equine CT come from?
- peripheral infoldings of the enamel organ
71
What are the major cytodifferentiative events?
| When do most of them occur?
- ectodermal cells lining concave aspect of enamel organ become internal enamel epithelium
- ectodermal cells lining the convex aspect of the enamel organi form the external enamel epithelium
- stellate reticulum forms between the layers for nutrative and mechanical functions during enamel formation
- between the cap and bell stage
72
What do the internal enamel epithelial cells become?
- tall columnar cells with large proximately located nuclei inducing alterations at the molecular level in underlying dental papilla to make uppermost cells enlarge to form odontoblasts
73
What do the newly formed odontoblasts do?
| What happens to internal epithelium after that?
- lay down along basal membrane a layer of dentin. Then basal membrane disintigrates
- overlying internal enamel epitheleal cells differentiate into ameloblasts and begin to produce enamel.
74
What do early ameloblasts do?
- deposit structureless enamel layer, migrate away from enamel-dentinal interface and form projection called Tomes process at distal aspect.
75
What does Tomes process do?
- proximal aspect of process forms interprismatic enamel
| - surface of Tome's process form enamel prisms
76
What are two phases of enamel, dentin and cementum formation?
- first secretion of extra cellular matrix of mucopolysaccharides and organic fibers
- then mineralization
77
Where does mineralization begin in multi-cusped teeth?
- at each cusp tip, progressing down towards the amelodentinal junction
78
Why don't odontoblasts and ameloblasts get trapped in their own secretions?
- move in opposite directions
79
What age does calcification of deciduous CT buds start and end in horses?
Which develop first?
When does calcificaion of first permanent tooth bud start?
- starts around 120th day of fetal life
- ends by 240 days
- 06s
- about 6 months later
80
Where and when does vascularization start in brachydont teeth?
How is enamel epithelium supplied prior to this?
- at the periphery of the tooth germ at early cap stage, then grow into dental sac and dental papilla
- mesenchymal capillaries
81
What happens to the connection between enamel epithelium and dental papilla when dentinal and enamel mineralization starts?
How is the enamel nourished?
- lose the connection
| - surrounding dental sac
82
In brachydont teeth, what happens once the crown is formed?
| What does new structure do?
- external and internal enamel epithelial cells at cervical region proliferate over dental papilla forming Hertwig's epitheleal root sheath.
- root sheath induces underlying mesenchymal cells to differentiate into odontoblasts that produce dentin
- sheath disintigrates and and dental sac cells come into contact with dentin which makes the dental sac mesenchymal cells tranform into cementoblasts and make cementum
83
What happens in equine teeth regarding cementum deposition that differs from brachydont teeth?
- deposited over whole tooth
84
What happens to epithelial root sheath when equine tooth has reached full length and what is consequence?
- distintigrates
| - can no longer make enamel
85
What are cementoblasts supplied by in the infundibula
What happens to blood supply after eruption?
What is consequence of this in terms of cementum filling infundibula?
- dental sac and openings in apical aspect of infundibula
- dental sac gets destroyed by mastication so cementun no longer has any occlusal blood supply so is effectively "dead" however, apical cementum can be nourished from apex
- can result in central infundibular cemental hypoplasia
86
What percent of the tooth in a young adult horse is clinical crown?
Reserve crown?
- 10-15%
| - 90 - 85%
87
What are two parts of reserve crown?
- alveolar
| - gingival
88
What is average length of fibers in equine feces?
3.7 mm
89
What is rate of eruption of hypsodont teeth?
What is rate of attrition on grass?
What other food produce this rate of attrition?
- 2-3 mm/year
- same
- hay or silage
90
What are teeth with a limited growth period called?
| Are hypsodonts in this category?
- anelodont
91
Do horse teeth have roots at eruption?
What part of the tooth is considered the root?
What do roots do after tooth is completely erupted?
- not true roots
- The part without enamel
- result in further growth of tooth for a year or so
92
What does apical refer to in horses?
- the bottom of the tooth even before it has roots
93
What percentage of teeth have no roots at 12 months?
- 25%
94
Why do mandibular CT in horses have more peripheral enamel infolding?
- no infundibula
95
When do deciduous 01s erupt?
02s?
O3s?
- 2-3 days
- 4-6 weeks
- 6-9 months
96
How do you distinguish deciduous incisors than permanent?
- whiter, wider, shallower infundibula
97
What is deciduous formula of deciduous teeth?
| Permanent teeth?
2 (i3/3, c0/0, pm3/3) 24 teeth
| 2 (i3/3, c 1/1 or 0/0, pm 3/3 or 4/4, M 3/3 (36-44 teeth)
98
What are first premolar teeth called?
- wolf teeth
99
What is the enamel spot and which teeth is it found on?
- ring of enamel left behind when infundibular cavity of incisor teeth gets worm away
100
What is the dental star and where is it found?
| How does it change over time?
- regular and irregular dentin on the occlusal surface of incisor teeth that has been deposited in the former pulp cavity.
- starts out as a yellow (due to food staining) transverse line at the labial aspect of the infundibulum and becomes oval with wear and moves to center of occlusal surface
101
What is Galvayne's groove?
When does it appear?
When does it reach occlusal surface?
- longitudinal groove that appears on labial aspect of permanent upper 03s
- 10
- 20
102
What is a 7 year notch (or hook)?
- overgrowth on the caudolabial aspect of the occlusal surface of 103 and 203 that appears around 6 years of age from incomplete contact between upper and lower 07s
103
How does the cross-sectional shape of incisor teeth change with age?
- start out elliptical, then become round, triangular then oval, especially lower 01s and 02s
104
What do deciduous canine teeth look like?
- vestigial spicule structures 0.5 -1 cm long that do not erupt above the gums
105
When do adult canine teeth erupt?
- 4-6 years
106
Why do canine teeth get calculus?
No occlusal contact
107
What percentage of mares have canine teeth?
| in donkeys?
- 7.8 - 28% horses
| - 17.3-30%
108
How long are canine teeth in thoroughbred, how much in unerupted crown in young horse?
what is consequence?
- 5-7 cm
- as little as 10-20%
- hard to extract
109
Why is reduction of canine teeth in horses not recommended
- pulp in young horses can be within 5 mm of occlusal surface
110
What is unique about wolf teeth?
| How long are roots?
- they are brachydont
| - 0 - >30 mm in length
111
When do wolf teeth erupt?
- 6-12 months of age
112
What is prevalence of wolf teeth in males?
females?
both?
- 14.9%
- 24.4 %
- 13-31.9%
113
When do deciduous pms erupt?
at birth or shortly after
114
When do permanent PMs erupt?
06 - 2.5
07 - 3
08 - 4
115
How are deciduous cheek teeth differ from permanent teeth in shape?
- have a neck
116
When do the molar teeth erupt?
09 1
10 2
11 3.5
117
Which are more square-maxillary teeth or mandibular teeth?
- maxillary
118
What are the ridges on the buccal aspects of upper cheek teeth called? How many are they and what do they look like?
What is exception?
- cingula, styles
- 2 vertical rostrally and less prominent caudal ridge with two deep grooves between
- 6s that have 3-4 small grooves and ridges.
119
How do cingula correlate with points?
- horses with prominent cingula more likely to develop maxillary poitns
120
Does the mandible have cingula?
- less prominant
121
How many roots do the upper cheek teeth have?
- usually 3 (two lateral and one flat medial) but medial root can divide into 2 roots.
122
How many roots do the lower cheek teeth have?
| What is exception?
- 2
| - the 11s have 3
123
Where are the alveoli of the upper 06s and 07s (and sometimes the rostral 08)?
- the maxillary bone
124
Where are the alveoli of the caudal 08 and the 09?
| The alveoli of the 10s and 11s?
- in the rostral maxillary sinus
| - in the caudal maxillary sinus
125
What can be the result of periapical infections of the caudal cheek teeth?
- sinus empyema
126
Are diastema in incisor teeth a problem?
| In CT?
- no
| - yes because food accumlates in space
127
What is curve of spee?
What breeds is this marked in?
Where else can there be a curve?
- caudal 2-3 cheek teeth curve dorsally in caudal direction.
- arabian with dished face
- rostral teeth
128
What is anisognathia and is it normal in horses?
- wider maxillary tooth "arch" than mandible
| - yes
129
What is normal range of side to side angulation of horse teeth?
How else are they angled?
- 15 - 35degrees
| - also dorsal on lingual to ventral on buccal
130
What is shear mouth and what causes it?
- excessive angulation (> 45 degrees in caudal mandible) from concentrate diet
131
What is a cusp in a horse tooth?
A ridge or style?
A transverse ridge?
How many transverse ridges does a horse have?
- elevation on occlusal surface from thicker enamel
- linear elevation on occlusal surface or periphery of tooth
- ridges that run on occlusal surface of CT
- 12
132
What is the cusp pattern of horse teeth?
- lophodont (crest teeth)
133
What are two kinds of alveolar bone?
compact bone that lines alveolus (lamina dura) into which Sharpeys fibers insert
main alveolar bone
134
What are the main equine salivary glands?
| Where else is there salivary tissue?
- parotid, mandibular, sublingual
| - lips, tongue, palate and buccal regions
135
What is the largest salivary gland and how much does it weigh?
- parotid
| - 200 gm
136
How much saliva does a thoroughbred produce in 1 min?
- 50 ml
137
What is grass gland?
When the parotid salivary gland enlarges and protrudes above the masseter muscle when horses are turned out to grass.
138
What is sometimes embedded in the parotid gland?
| What structures does the parotid gland cover?
- jugular
- stylohyoid bone, carotid artery, facial nerve, guttural pouch, origins of the brachycephalicus and sternocephalicus muscles
139
What muscles separate the parotid salivary gland from the mandibular salivary gland?
- sternocephalicus
| - brachiocephalicus
140
What tissue is found at the dorsal aspect of the salivary gland?
What diseases is this tissue significant in?
- lymphoid
| - strangles or other purulent tissues-causes distention of the tissue
141
Where does parotid duct enter the mouth?
- 08s
142
Is the mandibular salivary gland palpable in the horse?
- No
143
What is the course of the mandibular salivary duct in the horse?
- travels the full length of the oral cavity beside the sublingual salivary gland, enters on the lateral aspect of the sublingual caruncle
144
Where is the sublingual salivary gland?
From symphysis to 09 with multiple small ducts into the mouth
145
What kinds of mucosa are there in gingiva and hard palate and how is it connected to subQ tissue of horses?
What is consequence of attachment to subQ tissue?
- keratinized, orthokeratinized ro parakeratinized with deep rete pegs into subQ tissue
- limited mobility
146
What is gingival sulcus of horse lined by?
non-keratinized mucosa
147
Where is most common rostral fracture site?
- suture between incisive bone and maxilla
148
What causes focal swelling in young horses rostrally?
- eruption cysts of 06-08s
149
What muscle must be displaced in the horse to allow local bolock of infraorbital nerve?
What does this block anesthetize
- levator labii superioris muscle
| - upper 06, maybe 07
150
What is chewing power stroke in dogs?
In horses?
What is horse power stroke called?
- vertical
- transverse in lingual direction
- lingual power stroke
151
What are most important masticatory muscles in the horse?
What are they innervated by?
What innervates the facial muscles (muscles of expression)?
- pterygoideus, masseter
- mandibular branch of the 5th CN
- 7th CN
152
What muscle opens the mouth?
- digastricus
153
Which is larger in the horse, the coronoid or the condyle?
- condyle
154
What muscle opens the mouth?
- temporalis
155
What is the difference between carnivore temporalis muscle and coronoid process and equine?
Why?
- much larger in carnivores
| - carnivores need to crush prey
156
Does the TMJ have a joint capsule?
| Does it have ligaments in the horse?
- yes
| - indistinct lateral and elastic posterior
157
When do the equine mandibles fuse?
2-3 months`
158
What are osseus tubercles?
When do they occur, when do they go away?
What predisposes horses to forming these?
- mandibular eruption cysts due to imblance between mandibular depth and tooth length
- 3-5 years of age, over next 1-2 years unless they fistulate
- maybe from crossing between horses with shallow mandibles and short reserve crown (warmbloods) and horses with deep mandible and long reserve crowns (coldbloods)
159
Where does the mental nerve emerge in horses?
- mental foramen halfway between 06s and incisors
160
What anatomical weakness results in sequestration of alveolar lining in some cases after oral extraction of cheek teeth.
- spongy and porous bone beneath lamina dura in horses (probably due to constant remodeling b/c similar to bone in children)
161
Where do nerves enter the tooth?
Where do they go and what do they form?
Where do they come from?
-apical foramen for sensory nerves
Plexus of Rachkow in the coronal region
- CN5 for sensory nerves, cervical ganglion for sympathetic fibers that supply vascular smooth muscles that control blood flow to the pulp and differentiation and function of odontoblasts
162
What most likely causes post-rasping pain in horses?
- damaged dentin or pulp expousure
