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CTB SSA Flashcards

1
Q

Concrescence

A

roots have fused together due to cementum

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2
Q

most likely to be missing if a cleft palate has not fused with the pre maxilla

A

Lateral incisors

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3
Q

signalling in initiation stage, bud stage, cap stage

A

Initiation stage:
-Overlapping gradients of signalling molecules (“morphogens”; FGF, BMP) in the dental epithelium induce a transcriptional response (PAX9, MSX1) in the dental mesenchyme
BMP in regions adjacent stops Pax-9/Msx-1 signalling
(PAX9 will form a tooth )

Bud stage:
-Dental mesenchyme secretes signalling molecules (FGF, BMP) and induces formation of the enamel knot (= non-dividing cells) in the dental epithelium.

Cap stage:
-The enamel knot secretes signalling molecules that induces cell cycle arrest (BMP) within enamel knot cells but induces cell proliferation (FGF) in surrounding cells  Determination of tooth shape

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4
Q

Three processes the maxilla undergoes during growth in adult displacement and relocation:

A

Growth of the maxilla in height
-Bone deposition at the zygomatic and frontal sutures
Bone remodelling at alveolar processes
-Bone remodelling of the hard palate - deposition on inferior palatal surface and resorption at the superior surface

Growth of the maxilla in width

  • Growth at midpalatal suture
  • Some external bone remodelling

Growth of maxilla in length

  • Growth at posterior surface of maxillary tuberosities
  • Bone remodelling in area above maxillary incisors
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5
Q

Two processes the mandible undergoes during growth in adult displacement and relocation:

A

Forward and downward displacement in relation to the cranial base results in:

  • Growth of condylar cartilage
  • Bone remodelling of the ramus - bone dep and resorp along posteiror and anterior margins of the ramus respectively
  • Forward and downward displacement of the mandible results in backward and upward growth of the condyle and ramus
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6
Q

Causes on mandibular rotation:

A

Growth of the cervical region of the vertebral column displaces the head from the shoulder girdle

Growth and stretch of chain muscle groups e.g. mandible to skull base, mandible to the hyoid bone, hyoid bone to the shoulder girdle

Descent of the mandibular symphysis and hyoid bone relative to the cranial base -> inc. anterior face height

Growth of the middle cranial fossa and condyle -> inc. posterior face height

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7
Q

Consequences of mandibular rotation:

A

Forward rotation - excess growth in posterior face height

Backward rotation - excess growth in anterior face height

Mandibular and dentoalveolar compensation can restore normal occlusion

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8
Q

The process that undergoes to reduce the curvature of baby bones in the skull

A

Deposition on the inner surface of the flat skull bones. Bone remodelling along external and internal surfaces of growing skull bones reduces their curvature.

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9
Q

Why is the shape of the head different in craniosynostosis

A

premature fusion of sagittal or coronal sutures leads to sutural growth in orientation that is not fused

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10
Q

The cementum is thicker in the apex and interradicular areas because

A

Due to deposition at the apex to compensate for enamel erosion, or mesial drift.

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11
Q

Histological difference between the cervical loop and HERS

A

ervical loop has stratum intermedium, stellate reticulum, OEE and IEE whereas HERS just contains OEE and IEE and begins to break down during root dentine formation

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12
Q

What happens to cause enamel pearls

A

2 possible causes

  1. Localised attachment of epithelial cell rests (ECR) to predentine (caused by absence of cementum deposition) if its not separated by cemtnoebalsts coming in and producing cementum. - Molecular signals from predentine could initiate ameloblast differentiation
  2. When HERS/root development is initiated, stratum intermedium/stellate reticulum cells of the cervical loop could become trapped in a subset of ECRs. (Berkovitz)
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13
Q

Role of the cervical loop

A

The cervical loop is the growing end of the enamel organ (cell interactions and determination) it is located where IEE and OEE meet and is later involved in root formation as it is the precursor for HERS.

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14
Q

A child presents with opacities on the occlusal side of incisors and all four first molars. You ask if she used to swallow toothpaste as a baby and when first learning to brush teeth or whether she is from a foreign country. What problem are you trying to eliminate?

A

fluorosis

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15
Q

What disease affects all enamel in all the teeth

A

amelogenesis imperfecta

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16
Q

What fails to fuse in bilateral cleft lip

A

medial nasal processes and maxillary process

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17
Q

Adult bone has a compact structure on the outside and trabecular inside - why?

A

compact bone makes the structure stable; trabecular bone makes it light so movement can occur

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18
Q

Osteocytes are linked in caniculi

A

This forms a network of cellular processes that connect adjacent osteocytes. They function as sensors of changes in the bone environment; signalling centres to maintain bone integrity (i.e. induce remodelling).

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19
Q

Cementocytes are linked to the PDL for nutrition

A

Via canaliculi, different to osteocytes as the each osteon has its own vascular supply.

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20
Q

Functions of REE:

A

stops resorption of the tooth during osteoclast remodelling.

Fuses with oral epithelium during eruption to prevent bleeding. Forms the junctional epithelium in oral mucosa - later Naysmyth’s membrane which forms the gingival sulcus and fills with GCF

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21
Q

Functions of the layers of the enamel organ: IEE

A

columnar epithelial cells that become preameloblasts which then differentiate into ameloblasts. At the end of enamel maturation stage the REE is formed by the IEE and other remnants of the enamel organ (mainly OEE).

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22
Q

Functions of the layers of the enamel organ: SI

A

ayers of flat epithelial cells that support ameloblasts; control nutrients and waste products and produce alkaline phosphatase which is involved in enamel mineralisation.

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23
Q

Functions of the layers of the enamel organ: SR

A

Star-shaped epithelial cells involved in protection. They are separated by GAGs that hydrate the tissue, and mechanically support the tooth germ.

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24
Q

Functions of the layers of the enamel organ: OEE

A

Cuboidal cells that exchange substances with the DF and also help maintain tooth shape.

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25
What is the problem in hypertelorism
eyes are spaced wide apart due to over expression of SHH. Increased distance between the orbits
26
posterior cleft palate is incomplete fusion of what
incomplete fusion of the left and right maxillary processes
27
Teeth involved in anterior cleft palate
incisors, laterals may be absent, centrals with developmental defects
28
What does HERS form -
formation of dentine in the root by inducing differentiation of dental papilla cells. Can form lateral root canals in development. Forms rests of Malassez as it disintegrates
29
Hyperplasia that causes a problem in extraction
hypercementosis
30
How is digeorge diagnosed
deletion in Ch. 22q.11.2 - learning difficulties, cleft palate, specific facial features - TBX1
31
Why would hypercementosis make extractions difficult
can lead to attachment to the surrounding alveolar bone
32
Primary displacement
Growth in one location causes the bone to be pushed away from other structures (i.e. condyle growth).
33
Secondary displacement
Relocation of bones that are not growng themselves i.e. displacement of the toes from the pelvis as the femur grows.
34
Problems associated with HERS persistence
periodontal cyst- They can block eruption pathway, if a tooth wants to erupt and if it hits the cysts then the eruption pathway will be blocked
35
Skeletal patterns and head forms; which has the greater cranial base flexure; mandible type:
Orthognathic Retrognathic - cranial base angle more obtuse -> backward rotation of the mandible. Dolichocephalic head. Letotproscopic face Prognathic - cranial base angle more acute -> forward rotation of the mandible. Brachycephalic head. Euryproscopic face.
36
common cephalometric planes
maxillary plane - Anterior nasal spine to Posterior nasal spine mandibular plane- Menton to Gonion anterior cranial base- Sella turcica to Nasion (check diagram from slides)
37
what are Cephalometric points what is the frankfurt
nasion, gonion, sella; normal angles between the points Frankfurt line is the line along the floor of the orbit between the nasion and sella turcica.
38
Size of PDL (average width)-
* PDL thickness: 0.15 – 0.38 mm; thinnest in middle third of the root: * 11-16 years: Ø 0.21 mm * 32-52 years: Ø 0.18 mm * 53-67 years: Ø 0.15 mm
39
What is the mildest form of posterior cleft palate
uvula division
40
What tissues are affected in cleft palate/lip -
hard and soft palate, oral mucosa, dentition, upper lip, nasal septum, base of the nose, nasolacrimal duct
41
What two features do not fuse to produce a posterior cleft palate
The palatal shelves of the secondary palate. another answer?? Secondary palatal shelves and maxillary processes
42
What induces the formation of HERS
Once crown formation is complete, epithelial cells of the IEE and OEE proliferate downwards from the cervical loop of the enamel organ to form a double layer of cells - the HERS.
43
What is the embryological origin of HERS?
ectoderm
44
Problems associated with HERS
rests of malassez can persist and form cysts. These can be induced to form cementum (cementoblasts) and periodontium
45
What can get trapped that would cause an enamel defect in the root
enamel pearls; SI/SR trapped in HERS or HERS comes under signalling from dentine to form ameloblasts
46
Structural difference of primary and secondary dentine
There is a change in direction of the dental tubules in secondary dentine- S-curve of the tubules is more accentuated in the secondary dentin, d and it is irregular distribution ; mostly found on the roof and floor of the pulp chamber Secondary is more highly mineralised than primary and is also harder, fewer tubules in secondary than in primary
47
The growth sites for primary and secondary displacement of nasomaxillary complex and mandible:
NMC -frontomaxillary suture, zygomaticotemporal suture, zygomaticomaxillary suture, pterygopalatine suture Mandible - see above
48
Hydroxyapatite structure
HA combine to form prisms which are separated by inter-prismatic regions.
49
Mechanisms of fluoride action
formation of fluoroapatite which is harder to dissolve than hydroxyapatite due to higher KsP; integrates mainly in pits and fissures
50
Why do you not give tetracycline to children
causes permanent discolouration of the teeth.
51
Hypercementosis -
abnormal production of cellular cementum as a result of age, paget’s disease, idiopathic or occlusal trauma.
52
Determining tooth shape
pax9
53
What fails to fuse in bilateral cleft
The medium nasal processes and the maxillary processes.
54
What is the function of osteocytes
Are joined to each other via canaliculi and act as sensors to that stimulate bone remodelling.
55
Give the time scales for primary and secondary cartilages
primary cartilages form via endochondral ossification 5 weeks-7 months. Secondary cartilages - seen postnatally e.g. in the condyle
56
Gene that mutates to cause cleft palate
IRF6, TBX22, MSX1, FGFR1
57
Bone modelling stage
Formation, Resting, Resorption, Reversal
58
Dentine hypersensitivity
sharp pain, exposed dentine, all stimuli - hydrodynamic theory
59
Reversible pulpitis
short duration, goes when stimulus is removed. Preserve pulp
60
Irreversible pulpitis
long duration, persists, cold reduces pain. pulpotomy, puloextomy, extraction
61
Apical periodontitis
asymptomatic (apical radiolucency)/symptomatic - TTP
62
Periapical abscess -
acute (TTP, swelling)/ chronic - mild TTP, draining sinus
63
Bleaching sensitivity
H2O2 penetrates to pulp -> inflam or inc tubule patency
64
3 differences between male and female skull -
Male - bulky, wide and long nose and facial growth occurs into the 20s. Females - growth stops after puberty, flatter more delicate and have little overhang of the supraorbital ridges. The zygomatic bone is also more prominent in females.
65
Dentine that forms too quickly -
interglobular
66
Physical difference between enamel and dentine:
Enamel - more mineralised (96%), non-amelogenin proteins e.g. enamelin and tuftelin; rods and interrods. Absence of ameloblasts Dentine - less mineralised (70%); dentine proteins, collagen (I and III); dentine tubules - primary, secondary, tertiary. Odontoblasts present.
67
Give 3 examples of risks associated with orthodontic treatment concerning the tooth and tooth structures
Root resorption, alveolar bone loss and desensitisation of the tooth.
68
What is the advantage of prism decussation
Prevents the propagation of any cracks through the enamel.
69
Transcription factor determining what tooth type results
Barx1 is a transcription factor that determines molar formation. It is not present in the anterior teeth during formation whereas Msx1 is.
70
What histological feature is visible at late bell stage
Early - enamel organ is distinguished by the OEE, the SR and the IEE. Mesenchymal cells of the dental papilla and follicle continue to proliferate. The SI is also present. Late bell stage - the tooth has acquired its future shape, odontoblasts secrete dentine matrix and ameloblasts secrete enamel matrix. The SR moves downwards to protect the cellular area of the developing tooth. The cervical loop is the growing end of the enamel organ. There is a breakdown of dental lamina as the enamel organ loses contact with oral epithelium.
71
Drinking hot and cold drinks - sharp pain but no carious lesion present - what is this? How would you treat it?
Dentine hypersensitivity - may want to X ray to check there is no caries beneath the lesion Fluoride varnish - desensitising agent Seal and protect which blocks the dentine tubules if this does not work Prescribe sensitive toothpaste
72
What happens if the dental lamina does not break down
odontomes and eruption cysts
73
Sclerotic dentine and dead tracts, why they form and how it differs in root and crown, why it appears transparent
Sclerotic dentine forms as a result of age (roots) or enamel attrition (coronal dentine), it is the increase in peri-tubular dentine and it also prevents the spread of dental caries. Dead tracts are dental tubules where odontoblast processes have retracted and the remaining space has been filled with air
74
Hypodontia
Msx1 (lower premolars) and Pax9 (molars)
75
Role of sub mucosa -
provides mobility and acts as a cushion for the lining mucosa. Adipocytes present
76
Process by which teeth form
redundancy of TFs e.g. Pax9 and Msx-1
77
What is the embryological origin of olfactory sensory epithelium?
Olfactory placode
78
• Which teeth are most likely to be missing in the cleft lip area?
Upper lateral incisors | The second premolars are next likely to be missing-
79
Name 4 functions of the reduced enamel epithelium?
forms the junctional epithelium protects the enamel from being resorbed by osteoclasts that resorb bone as part of the eruption process, or from abnormal cementum deposition. ??
80
2019 CS starts here - What is the critical time period where cleft lip and palate is most likely to develop and what are the 4 main developmental causes of cleft secondary palate?
6 weeks cleft lip 9 weeks cleft palate • Early growth or morphogenetic defect : - Reduced cell proliferation of mesenchymal cells - If they elevate they can’t fuse • Premature epithelial fusion: - Epithelium of palatal shelves fuses with other oral epithelia • Failure of palatal shelf elevation: - Mechanical obstruction or abnormal cell differentiation in ‘hinge’ region of palatal shelves • Late growth defect: - Reduced cell proliferation of mesenchymal cells • Secondary effects: - e.g. abnormally wide head (in craniosynostosis) • Epithelial fusion defects: - Failure of the epithelium to break down during fusion
81
i. What are the mechanical processes which occur in the formation of bud stage?
Formation of a tooth bud (8 weeks in utero): - Elongation of the dental lamina - Formation of localised swellings on the deep surface (“tooth buds”; A) - Condensation of mesenchymal cells surrounding the tooth bud (B)
82
What are the cellular interactions which occur in the formation of bud stage?
Dental mesenchyme secretes signalling molecules (FGF, BMP) and induces formation of the enamel knot (= non-dividing cells) in the dental epithelium. - Target is in the epithelium
83
Give three possible negative effects of orthodontic treatment on the structures/surrounding structures of the tooth
Root resorption - Transient inflammatory response and Can cause loss of vitality in pulp - Reduction in alveolar crest
84
Give 2 features of the term “infra-occlusion”
Ankylosis resulting in submerged tooth | - Prevention of exfoliation- impact on successor
85
i. What is the cause of a class III facial profile?
``` Brachyocephalic head (Asian populations) - retrognathic maxilla, a prognathic mandible, or both ```
86
What are the other features of a class III relationship concerning the mandibular angle, occlusion and jaw relationship?
Cranial base angle more closed (acute) forwards rotation of the mandible. This is influenced by growth at the Spheno-occipital synchondrosis. - Prognathic jaw relationship - Occlusion- the upper molar is a full tooth width distal to the Class I position
87
What effect is also seen in the anterior teeth?
The lower incisor edges lie anterior to the cingulum plateau of the upper incisors - Upper incisors tuck into lower
88
What is the suture which closes at ages 7-8 and what bones make this up?
Metopic suture – 7months – frontal bone - Interspehnoidial is 7 months in utero - Spheno-ethmoidal syncrondrosis (anterior cranial base) ( 7 years ) pre-sphenoid and ethmoid bone
89
ii. What is the function of these sutures?
Synchondrosis - Contribute to cranial base growth- important growth centres
90
i. The inner layer of skull bones is adapted to the function of sutures, what is this layer and what is its function?
?? no answer yet

Extra Stage 2 (14 decks)

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