CTB Flashcards
1
Q
Concresence
A
Fusion of teeth after eruption due to fusion of their cementum surfaces
2
Q
Causes of concrescence?
A
Crowding or trauma
3
Q
Dilacerated root?
Cause
A
Curved or bent roots
Developmental trauma
4
Q
Cause of multiple (lateral) roots?
A
Abnormal folding of HERS
5
Q
IF cleft palate fuses with premaxilla what teeth are likely to not develop?
A
Lateral incisors
6
Q
Process of tooth development with signalling molecules involved in enamel knot formation
A
Initiation stage - overlapping gradients of signalling molecules (BMP and FGF) cause transcriptional response in dental mesenchyme (PAX9 and MSX1). Determines tooth position
Bud stage - mesenchyme secretes FGF and BMP and induces formation of enamel knot in dental epithelium
Cap stage - enamel knot secretes signalling molecules, BMP induces cell cycle arrest in enamel knot cells, FGF induces cell proliferation in surrounding cells. determines tooth shape
7
Q
2 processes the mandible undergoes during growth in adult displacement and relocation?
A
Adult growth = bone remodelling Bone formation (osteoblasts) Bone resorption (by osteoclasts)
8
Q
Rotations within the mandible, causes and results?
A
Forward rotation, due to excessive growth in posterior face height = deep bite
Backward rotation, due to excessive growth in anterior face height = open bite
9
Q
How does anterior and posterior face height increase?
A
Growth at cervical region of vertebrae displace head from shoulder girdle
This causes stretch of muscles from mandible to skull base, from mandible to hyoid and from hyoid to should girdle
This causes descent of mandibular symphysis and hyoid bone resulting in increased anterior face height
Growth of condyle = increased posterior face height
10
Q
How does craniosynostosis change head shape?
A
Premature fusing of sutures of the skull
So brain expansion causes excess bone growth in the parallel direction to ensure intracranial pressure does not increase
Saggital craniosynostosis = long
Coronal = wide
11
Q
Why is cementum thicker at apical and interradicular regions?
A
This is where cellular cementum is deposited as we age due to masticatory forces to ensure tooth stays in occlusion
12
Q
Histological difference between cervical loop and HERS?
A
Cervical loop = IEE, OEE, SI, SR
HERS = IEE and OEE only
13
Q
Formation of enamel pearls
A
Epithelial rests of mallassez formed when HERS stretches and degenerates but leaves remnants
Epithelial rests can form enamel pearls
Due to localised attachment of rests to predestine due to lack of cementum. Signs from pre-dentine could cause HERS cells to differentiate into ameloblasts (Stem cells) or if remnants of SI, SR stuck in HERS, they can then signal ameloblast differentiation
14
Q
What is the cerivical loop and what is its role?
A
Growing end of the enamel organ (IEE, SR, SI, OEE), involved in cell interactions and root formation
15
Q
How is cervical loop involved in crown formation?
A
IEE of the cervical loop separated from dental papilla by a cell free zone
IEE elongate into pre-ameloblasts and release signals for differentiation of odontoblasts from dental papilla cells
Odontoblasts align and produce pre-dentine
Signals from odontoblasts in pre-dentien induce differentiation of pre-ameloblasts into ameloblasts and produce pre-enamel
16
Q
How is cervical loop involved in root formation?
A
IEE and OEE of the cervical loop proliferate down after crown formation and form a double layer of epithelial cells = HERS
17
Q
A child presents with opacities on the occlusal side of the incisors and all four first molars. You ask if she used to swallow toothpaste as a baby and when learning to first brush teeth or whether she is from a foreign country. What problem are you trying to eliminate?
A
Dental fluorosis
18
Q
What do cephalometric line show?
A
Angles
Determine skeletal pattern and anteroposterior position of dentition
19
Q
2 classes of skeletal relationship according to angles and what do both show?
A
Class II = retrognathic = mandible posteriorly displaced
More acute angle associated with taller head (docicephalic)
Div I = U1 proclined = larger overjet
Div II = U1 retroclined = normal overjet
Class III = prognathic = mandible more anteriorly displaced = more obtuse angle
associated with wider head (brachycephalic)
20
Q
Compensation of mandibular rotation
A
Skeletal compensation - open bite (backward rotation)
Growth of wider ramps will more mandible forward
Dento-alveolar compensation - open bite means mandibular incisors grow up and maxillary incisor grow down to reach occlusion = curve in occlussion
21
Q
Width of mantle dentine?
A
20-150 micrometres
22
Q
How is mantle dentine framed and what are its properties?
A
Formed from newly differentiated odontoblasts (first to be formed), lacks phosphoprotein, highly acidic and attracts calcium = reduced demineralisation
Loosely packed collagen fibrils and strongly branched tubules = prevent cracks
23
Q
Width of dentine in root corresponding to mantle?
A
Hyaline = 20 micrometres
24
Q
Size of PDL
A
0.15-0.38mm - thinnest in the middle PDL thickness decreases with age 11-16 = 0.21 mm 35-53 = 0.18mm 53-67 = 0.15 mm Mastication increases PDL remodelling = increased width in areas of tension not compression
25
Disease affecting all enamel in teeth?
Amelogenesis imperfecta
26
What fails to fuse in bilateral and unilateral cleft palate?
```
Bilateral = failure of both maxillary processes to fuse with medial nasal process
Uni = on one side so only one maxillary process
```
27
What is the structure of the Trabecular bone, what does it contain, and why is it a structural component of the bone given that the compact bone is harder?
Trabecular bone contains many cavities filled with bone marrow interrupted by a network of bone plates
Compact bone is harder and forms the outer layer but it is very dense, trabecular bone allows the bone to be light and moveable
28
Osteocytes - how are they connected what is the purpose of this?
Osteoblasts that have become trapped in matrix
| Linked by cannaliculi - exchange nutrient and mechanical sensors to maintain bone integrity
29
Direction of cannaliculi of cementocytes? why?
Towards the PDL
| Connects cells to PDL to provide nutrients to cementocytes
30
REE
| Function
Remnants of enamel organs and flattened ameloblasts
| Surrounds the erupting tooth and prevents enamel from being resorbed by osteoclasts. Forms the JE
31
Function of layers of the enamel organ
```
OEE = cuboidal = exchanges substances with DF (nutrients and waste) via capillaries
DF = condensed mesenchymal cells surround the enamel organ = form the periodontium. Provide nutrients to OEE. Some capillary links with ameloblasts (when enamel and dentine form links with DP destroyed)
DP = condensed mesenchyme cells beneath the EO = form odontoblasts and fibroblasts of the pulp
SR = star shaped cells operated with GAGs between = protects the developing tooth and maintaining shape (cushioning)
SI = flat epithelial cells = ameloblast supporting function and produce alkaline phosphatase which aids mineralisation
IEE = form ameloblasts which form enamel (pre-ameloblasts signal fro odontoblast differentiation)
```
32
What are the embryological origins of the olfactory sensory epithelium?
Olfactory placodes and neural crest cells
33
Hypertolerism
Large distance between eyes
34
What does HERS form?
Epithelial rests of Malassez which allow dental follicle cells to enter and differentiate into cementoblasts
35
Give an example of a hyperplasia that causes problems during extraction? Why?
Hyperplasia = over secretion/formation
Hypercementosis = abnormally high cementum deposition
May result in attachment to surrounding alveolar bone or other teeth
36
Problems associated with HERS
Abnormal folding can cause the formation of lateral roots
| It can form epithelial rest of Malassez which can from periodontal cysts and enamel pearls in cementum
37
Embryological origin of HERS?
Proliferation of IEE and OEE from cervical loop after crown completion
IEE and OEE = epithelium = ectoderm
38
Structural difference between primary and secondary dentine
Visible change in tubule direction between the 2
Secondary dentine at the pulp border has fewer tubules and is unevenly distributed around the pulp chamber
Primary has more tubules (more odontoblasts when they were formed), the tubules are straighter
39
What is growth through primary and secondary displacement?
Primary displacement - growth in one one location causes the bone to be pushed away from other structures
Secondary displacement - Bone displaced as a result of growth of another bone
40
Example of primary and secondary displacement in nasomaxillary complex
Primary - growth at sutures causes forward and downward displacement e.g. growth at zygomaticomaxillary suture = maxilla down and forward
Secondary - growth of the middle cranial fossa displaces the nasomaxillary complex forward and down
41
Example of primary and secondary displacement in mandible?
Primary - condylar growth = forward and downward displacement
Secondary - growth of cranial base moves mandible forward and down
42
Reversible pulpitis
Short duration of pain that disappears when stimulus is removed (thermal and sweet)
43
Irreversible pulpitis
Long duration of pain that doesn't disappear when stimulus is removed.
Cold can make pain better by reducing pressure
44
Management of reversible vs irreversible pulpits?
```
Reversible = remove irritant and restore, preserving pulp
Irreversible = pulpotomy, pulpectomy or extraction
```
45
Identifying feature of apical periodontitis
Symptomatic = tenderness to pressure and widening of apical PDL
Symptomatic and non-symptomatic = apical radiolucency
46
Identifying feature of apical accesses
Tenderness to pressure
Radiolucency
Swelling
47
What is condensing osteitis? Identifiable feature?
Inflammatory disease after dental infection causing bone formation
Radiopaque
48
Alveolar osteitis?
after tooth extraction the socket fills with blood and forms a clot
Detachment of the clot can cause bone inflammation - bad odour
49
Identifiable feature of cracked cusp syndrome?
Small crack hard to see
Sharp pain on mastication
Pain goes when biting released
50
Identifiable features of pulp necrosis
Tooth much darker in colour
51
Identifiable feature of ankylosis
Tinny on percussion
52
What is ankylosis? - consequence
Fusion of tooth to bone - infraocclusion
53
Calcium hydroxyapatite formula
Ca10(PO4)6(OH)2
54
Solution of pH 9 on tooth
Critical pH 5.5, below this is rapid demineralisation
Normal pH of mouth 6.2-6.5
Above this the equilibrium moves to left and remineralisation occurs = bond making = exothermic reaction = temperature rise
55
Mechanism of F- action that contribute to caries resistance?
When bacteria produce acid hydroxyapatite dissociates
| Can then bind to fluoride which has a reduced solubility product = more resistant to acid
56
Why not give tetracylines to children?
High affinity for calcium, during development it would be incorporated into tooth structure and result in dark brown spots in enamel
57
Signalling molecule determining tooth shape?
BMP, FGF
58
Function of osteocytes
Presence of canaliculi allows recruitment of osteoblasts and osteoclasts to maintain bone homeostasis
59
When do paired primary cartilages develop?
6 weeks i.u
60
When do secondary cartilages develop?
10 weeks i.u
61
Name 3 secondary cartilages?
Condyle, coronoid and sympyseal
62
4 bone remodelling stages
1. Resorption - active osteoclasts = bone resorption
2. Reversal - disappearance of osteoclasts (apoptosis or migration)
3. Formation - activation of osteoblasts
4. Resting - cessation of been formation - surface covered in flat bone lining cells
63
Male vs female skull
```
Female = flatter and more delicate, zygomatic bone more prominent
Male = bulky, wide long nose, large overhang of supraorbital ridges
```
64
Dentine that forms too quickly?
Interglobular
65
Difference between pre-enamel and pre-dentine?
Pre-enamel is already partially mineralised (30%)
| Pre-dentine is completely unmineralised = 100% protein matrix
66
3 risks of orthodontic treatment
```
Root resorption (especially if history of trauma)
Decalcification
Relapse (PDL)
Transient inflammatory response in pulp
PD due to difficulty cleaning
```
67
Component of Tomes processes
Distal portion = prismatic (rod) enamel
| Proximal portion = inter prismatic (inter-rod) enamel
68
Advantages of prism decussation
Prevent propagation of cracks
69
Function of MSX1
Transcriptional response in dental mesenchyme to allow determination of tooth position - causing formation of enamel knot
Determines tooth identity (incisors)
70
Histological features present at late bell stage
```
Pre-dentine
Pre-enamel
SR
Cervical loop
Dental lamina breaks down
```
71
A patient comes into clinic with sensitivity to hot and cold drinks, he has sharp pains but no carious lesion present. What is this and how would you treat it?
Pulpitis
Pain isn't relieved by cold so probably reversible pulpitis
Remove irritant and restore, preserving the pulp.
Irreversible = pulpotomy, pulpectomy or extraction
72
What is a risk faced in the 3-8 week period of craniofacial development and what is the reason?
Weeks 3-8 = embryonic period (craniofacial development)
High susceptibility to teratogens
Failure of neural tube to close - anacephaly
73
Incomplete removal of dental lamina result in:
Eruption cysts
Supernumary teeth
Odontomes
74
Why does sclerotic dentine and dead tracts form, how does it differ in the root and crown, and why does it appear transparent?
Sclerotic = continues peritubular dentine formation to occlude tubules = transparent due to increased mineralisation
Dead tracts = recession of odontoblast processes in tubules = air filled
May be that root = due to ageing and mastication
Crown due to caries
75
Result of PAX9 and MSX1 mutation?
| Characteristics?
Hypodontia
PAX9 = missing molars
MSX1 = missing pre-molars
76
Role of submucosa
Loose connective tissue containing BV, N glands
| Mobility and cushioning
77
Phases of tooth development?
Initiation, morphogenesis, histogenesis
78
Problems in children with posterior cleft palate?
Cannot eat and breathe = problems breastfeeding
| Speech difficulties
79
3 functions of HERS
Extends around the pulp and defines future root shape
IEE of HERS induce odontoblast differentiation = root dentine
Curved end = epithelial diaphragm = primary apical fo.
Disintegration of HERS causes differentiation of odontoblasts, cementocytes and fibroblasts from DF
80
Bone holding anterior teeth structures?
Pre-maxilla
81
4 functions of REE
Fuse with OE to form a continuum so no bleeding on eruption
Protects the erupting crown from resorption by osteoclasts
Form JE
Forms Nasmyths membrane
82
Cephalometry
a) Sella
b) Nasion
c) Orbitale
d) A
e) ANS
f) PNS
g) B
h) Menton
i) Gonion
a) centre of sells turcica
b) point when frontal and nasal bones meet
c) base orbit
d) Deepest concavity on anterior maxilla
e) anterior nasal spine = tip of anterior maxilla
f) posterior nasal spine = posterior tip of maxilla
g) deepest concavity on anterior mandible
h) lowermost point of mandibular symphysis
i) most posterior-inferior point on angle of mandible
83
Cartilages giving rise to
a) lesser and greater wing of sphenoid
b) body of sphenoid
c) temporal
d) nasal cartilage
a) ala orbitali and ala temporalis
b) hypophyseal and trabecular
c) optic capsule and parachordal
d) paired nasal and prechordal
84
Most common cause of white patches in mouth?
Candida albicans
85
Most abundant type fo collagen in PDL?
Type 1 = fibrillar
| type 3 = reticular
86
Why are BV near PDL fenestrated?
To allow passage of nutrients to other cells e.g. cementocytes
87
What type of bone is made in response to fracture?
woven
88
What type of bone attached bone to PDL?
Bundle bone
89
Which movement requires a low orthodontic force?
Intrusion (15-25g)
90
How much force does tipping require?
50-75g
91
How much force does rotation and extrusion require?
50-100g
92
How much force does translation require?
100-150g
93
How does enamel repair?
Physicochemical processes
| Remineralisation
94
What fibre resists tooth extraction and intrusion
```
Extraction = oblique
Intrusion = alveolar crest, apical and interradicular
```
95
Name long period phasic lines in
a) enamel
b) dentine
a) Striae of Retzius
| b) Andresen lines
96
Name short period lines in
a) enamel
b) dentine
a) cross-striations
| b) Von-Ebner lines
97
What cell has tight junctions distally?
Ruffle-ended ameloblasts
98
Functions of ruffle ended ameloblasts
Increase mineral content of enamel
99
Function of smooth-ended ameloblasts
Decrease organic content of enamel
100
What cell has tight junctions proximally?
Smooth-ended
101
Describe the cranial base angle of retrognathic profile
Cranial base angle more obtuse = backward rotation of the mandible
102
Describe the cranial base angle of prognathic profile
Cranial base angle more acute = forward rotation of mandible
103
What head form, occlusion and mandible type would a small cranial base flexion person have?
Class III
Brachycephalic head
Prognathic jaw
Forward rotated mandible
104
What occurs during gastrulation?
Formation of ectoderm, mesoderm and endoderm, they fold
105
Derivatives of ectoderm?
Epithelium, CNS, neural rest cells
106
Muscular and skeletal derivatives of pharyngeal arches
```
I = trigeminal = muscles of mastication, mylohyoid. Malleus, incus, meckels cartilage
II = facial = muscles of facial expression, stapediua, stylohyoid. Stapes, styloid process, lesser horn of hyoid
III = glossopharyngeal = stylophayrngus. Greater horn of hyoid
IIII = Vagus = pahyengeal and laryngeal muscles. Laryngeal cartilages
```
107
How are neural crest cells specified?
By opposing gradients of signalling molecules at the border between neuroectoderm and epidermis
108
Fate of neural crest cells
Migrate to pharyngeal arches (due to signalling molecules)
109
Formation fo primary palate?
Merged medial nasal processes that continue inwards towards oral cavity
110
Persistence of oronasal membrane?
Choanal atresia = narrowing or blockage of basal airway by tissue
111
Formation of secondary palate?
```
Lateral outgrowths of maxillary processes (palatal shelves) grow downwards (7 weeks)
Shelves elevate (8 weeks)
Shelf fusion (9weeks)
```
112
Incomplete removal of medial epithelial seam?
Palatal cyst
113
Torus palatinus?
Benign overgrowth in midline of hard palate
114
Enchondondral ossification?
| Example?
Bone made from cartilage model (produced by chondrocytes and replaced by osteoid)
Condyle of mandible
Base of skull (synchondroses)
115
Intramembranous ossification?
| Example?
Bones made of osteoclasts differentiated from mesenchymal stem cells
Mandible
Maxilla
116
Sutural ossification?
| Example
Bones made from osteoblasts from mesenchyme but sutures proved fibrous connection =stability
Post-natal growth of skull
117
Perichondrium
| Formation
Source of cells that make chondrocytes
| Formed from chondrocytes derived from condensed mesenchymal cells
118
Structure of epiphyseal growth plate
Resting chondrocytes = reservoir to replenish chondrocytes being made into osteoblasts)
Proliferation chondrocytes = growth in one direction
Prehypterophic chondrocytes = swollen, increased cartilage matriculates
Hypertrophic chondrocytes = very large and swollen = fully matured
Calcification zone = cartilage being replaces by osteoblasts
119
Synchondroses
| Growth?
Cartilaginous jointed of cranial base
| Mirror image of 2 epiphyseal growth plates allows growth in both directions
120
Epiphyseal cartilage vs condylar cartilage
```
Epiphyseal = growth of endochondral bones (cartilage formed from chondrocyte proliferation, maturation and hypertrophy)
Condylar = mediates growth of intramembranous bone = mesenchymal cells respond to functional loading and differentiate into chondrocytes. random alignment = multi-directional growth
```
121
Suture
| Growth?
Fibrous joints between skull
| Skull bone growth in response to brain growth, respond to mechanical stress
122
Neurocranium
Cranial vault and cranial base = encloses the brain
123
Viscocranium
Facial skeleton = surrounds oral cavity, pharynx
124
Simple bone
Formed by ossification fo a single element e.g. endochondral or intramembranous
125
Compound bone
Formed by fusion of 2 or more ossifying elements e.g. maxilla = 2 intramembranous
Sphenoid = endochondral and intramembranous
126
When is Meckels cartilage formed?
6 weeks i.u.
127
Synovial joint
2 bones each covered with particular surface (hyaline cartilage) surrounded by fibrous capsule that creates a joint cavity filled with synovial fluid
128
TMJ movements
Rotation (horizontal) and translation (forward and backwards)
129
Fibrous layer covering the condyle contains ...
Progenitor cells that form chondrocytes that undergo endochondral ossification
130
How does cranial base grow?
Remodelling and synchondroses
131
Growth of what influences the angle of the cranial base?
Spheno-occipital synchondroses
132
How does cranial vault grow?
Remodelling and sutures
133
How does maxilla grow in height?
Bone deposition at symptomatic and frontal sutures
vertical drift of alveolar process
Deposition on inferior surface of palate and resorption on superior
134
Growth of maxilla in width?
Growth at mid palatal suture
135
Growth of maxilla in length?
Posterior surface of maxillary tuberosity
136
Forward and downward displacement of mandible results in...
Growth of condylar cartilage
| Bone remodelling of ramus
137
Early enamel formation?
Starts by secretion of enamel proteins, immediately partially mineralised
First layer is a prismatic and formed against mantle dentine. Tomes processes form - proximal = interprismatic, distal = prismatic
138
Function of amelogenins?
Form nano spheres which surround crystals and prevent them from fusing
Regulates growth and thickness of enamel crystals
139
Function of non-amelogenins?
Form enamel sheath
Enamelin = promotes and guides formation of enamel crystals
Amelobastin = adhesion of ameloblasts to enamel surfaces
140
What process can epithelial rest of malassez under go?
Epithelial-mesenchymal transition
141
How far do odontoblast processes extend in the tubules?
Normally to the EDJ
Increased age/attrition can cause retraction of processes (peritubular, dead tracts)
Some times can overshoot = enamel spindles
142
Main nerves in the pulp?
Mainly unmyelinated C fibres
Major = afferent (terminate at odontoblasts layers and transmit pain to CNS)
Minor = efferent (cause vasodilation/constriciton of capillaries)
Some myelinated afferent fibres
143
Equivalent to Contour lines of Owen in enamel?
Wilson lines
144
What does gnarled enamel look like and how is it caused?
Very angular prism decussation
Ameloblasts adapting to rapidly expanding enamel layer
Cohorts of ameloblasts are displaced apically by their own enamel production
145
Granular layer of Tomes
Where?
How?
Mineralisation?
Peripheral root dentine, beneath hyaline dentine
Extensive branching and backwards looping of odontoblast processes or incomplete fusion of calcospherites
Hypomineralised
146
Prism direction in primary and permanent teeth?
```
Primary = inclined occlusally
Permanent = inclined apically
```
147
Enamel tuft
Hypomineralised voids from EDJ extending a short distance into enamel following prism decussation, they contain residual enamel proteins
148
Enamel lamellae
Tufts passing through the full thickness of enamel containing organic material
149
Keratinisation status of gingival epithelium?
Parakeratinised plus some orthokeratinisation in areas of higher abrasive forces
150
Keratinisation of sulcular epithelium
Non-keratinised = binds gingival sulcus and may act as epithelial barrier
151
How is correct depth of sulcular epithelium determined?
Masticatory forces
152
What is Nasmyths membrane?
Primary enamel cuticle and remnants of REE
153
What is primary enamel cuticle?
Internal basal lamina produced by cells of REE, attached to enamel
154
How does junctional epithelium attach to enamel?
Via enamel cuticle and hemidesmosomes
155
How does structure of JE change in the deepest part compared to upper part?
Deepest part = REE cells (2-3 layers of cuboidal/flat epithelial cells)
Upper part = gingival epithelium cells (multiple layers of cells with epithelial ridges)
156
Consequence of inflammation on the sulcular epithelium?
Causes the epithelium to form long, irregular rate pegs that project into the lamina proprietary = epithelium hyperplasia . This is to compensate for collagen loss due to chronic inflammation
157
Why are monkeys gingival and palatal epithelium more orthokeratinxied than human?
Functional adaption - eat tougher food
158
What is submucosa made of?
Loose connective tissue (Fb), adipose tissue, minor salivary glands, BV and N
159
Where on the hard palate is submucosa found?
Lateral and posterior regions
160
Functional significance of epithelial-connective tissue interface?
Interdigitation of rete pegs and papillae of lamina proprietary increase SA and stability of epithelial-mesenchyme surface
161
Type of collagen in gingiva and palatal mucosa and why
Type 1 = fibrillar = high tensile strength and can resist shearing
162
When does condyle stop growing? What happens to the condyle cartilage?
16-20
Progenitor cells of proliferative zone stop dividing but cells persist through life. Endochondral ossification stops and condyle cartilage converted to fibrocartilage and highly calcified cartilage
163
Effect of bite jumping device on condyle
Pulls mandible froward inducing condylar growth
Chondroblasts of proliferative zone reactivated by mechanical stress, differentiate into chondroblasts = endochondral ossficiation
