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BDS3 University of Adelaide Dentistry > Orthodontics > Flashcards

Orthodontics Flashcards

1
Q

What are the 4 types of functional reasons for orthodontics?

A
  1. Increased Overjet
  2. Crossbites
  3. Labial Crowding in lower incisor areas
  4. Traumatic Overbite
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2
Q

What is the Gnomic Growth Pattern?

A

Growth occurs in a sunburst “explosion” pattern centred at the Pt point (inferior point of pterygomaxillary fissure)

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3
Q

According to Scammon’s Growth Curve, which system has peak growth in teenage years?

A

Genital

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4
Q

What is the Cartilage theory of craniofacial growth (Scott 1950) and why is it not current dogma?

A

Cartilage is primary determinant of skeletal growth and bones respond secondarily and passively

Debunked: Transplantation: some cartilage types (epiphyseal) grow, others (secondary cartilage, eg condylar) don’t

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5
Q

Where is the Pogonion (Pog)?

A

Soft tissue landmark - the most anterior point of the mandibular symphysis

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6
Q

What is Dental Arch Length?

A

Anterior/Posterior distance from central incisors to most distal point of permanent molars

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7
Q

What molar relationship is likely to occur for a mesial step that is less than 1mm?

A

76% Class I
23% Class II
1% Class III

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8
Q

What sort of chin is often portrayed in culture?

A

Prominent class III seen in superheros such as superman.

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9
Q

What are limitations of Ackermann-Proffit?

A

Static Analysis
No Aetiology
Little value if group number used - specifics needed
Only Profile used: neglected full face and smile views (mini-aesthetics)

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10
Q

What is required to stimulate chondrocytes to secrete cartilage in the condylar cartilage

A

Functional loading stimulates mesenchymal cells to proliferate and grow, ultimately differentiating into chondrocytes which secrete cartilage

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11
Q

What is primary crowding?

A

Primary Crowding: an inherent discrepancy between tooth size and the available arch length (jaw/ apical base size).

This is primarily determined by genetic origin

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12
Q

What are different direct measurements that can be used to gauge growth and development?

A
  1. Anatomical Measurements
  2. Hand Radiograph
  3. Secondary Sexual Characteristics (not really used in orthodontics)
  4. Lateral Cephalometry (including cervical maturation staging)
  5. Clinical Laser Scanning
  6. 3D Finite Element Model
  7. MRI
  8. CT Scanning
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13
Q

What is the emergence timing for primary dentition?

A 
6-7 months Lower As
7-8 months: Lower Bs and Upper As
9-10 months: Upper Bs
12-14 months:  Ds
16-18 months: Cs
24-30 months: Es
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14
Q

What is the embryological origin of the mandible?

A

1st Pharyngeal Branchial Arch: cells in the centre of the mesenchymal core differentiate into chondrocytes and form the arch cartilage

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15
Q

What is the main determinant of tooth position of accessional permanent teeth?

A

Skeletal growth of the maxilla + mandible + apical base

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16
Q

What is Traumatic Overbite?

A

Where the lower incisors traumatise the palatal gingiva in the upper arch to cause inflammation

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17
Q

Does Lip Separation increase/decrease with age?

A

With age: reduction of lip separation (incompetence) due to lower lip elevation

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18
Q

What factors predispose the possibility of root resorption during orthodontic movement?

A

Root shape

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19
Q

What is Bimaxillary Proclination (bimaxillary dentoalveolar proclination)?

A

Where both upper and lower incisors are proclined. This will coincided with reduced overbite and is often seen in ethnic variations

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20
Q

Why does the N angle change during growth?

A

Nasal Dorsum (the hump) can grow by 1mm/year during adolescence, changing the N angle by up to 30 degrees during peak growth period

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21
Q

What is Ackerman-Proffit Skeletal Class III?

A

Mx retrusive relative to Md

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22
Q

What are the two mid-sagittal sutures in the cranial base and where do they run from?

A

Anterior Cranial Base (ACB): Nasion to Sella Turcica – nasomaxillary attached

Posterior Cranial Base (PCB): Sella Turcica to Barium –Md indirectly attached

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23
Q

What is Class I Flush Terminal Plane relationship?

A

Flush relationship of Mx/Mn Es and where Mx C tip is distal to the tip of the Mn C.

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24
Q

What are the 6 categories of the Ackermann-Proffit Classification System?

A
  1. Alignment (Teeth via Lischer)
  2. Profile (Facial Aesthetics) Involves all soft tissue
  3. Types (Transverse relationship)
  4. Angle’s Classification (Sagittal AP relationship)
  5. Bite Depth (Vertical relationship)
  6. Overlapping Problems
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25
What gives the chin it's prominence with regard to the mandibular dento-alveolar ridge?
Prominence of chin results from relative lingual anterior movement of mandibular incisors at B point
26
What is a lateral ceph landmark that can be used to gauge malocclusion in the absence of an upper FPM?
Key Ridge - the anterior surface of the zygomatic process of the maxilla
27
What is Bjork Class Postnormal Occlusion?
Class II Occlusion - where the mandibular 1st molar is more than one-half cusp posterior of pre-normal relation
28
What molar relationship is likely to occur for a mesial step that is more than 2mm?
68% Class I 13% Class II 19% Class III
29
Which facial profile has natural divergence?
Straight Profile
30
How is Bolton's Analysis calculated?
1. Measure mesio-distal width of teeth 6-6 in both arches 2. Record the combine widths of the Mn vs Mx for: - Entire arch 6-6 - Anterior segment 3-3 3. Total Arch size is plotted on a 2 different X/Y axis graphs (entire arch & anterior segment) to calculate Bolton’s Discrepancy for both measurements
31
When does the condylar cartilage initially develop?
12 weeks in utero - after initial ossification of the mandible has begun
32
Where is the Nasion (N)?
Soft tissue landmark - The intersection of frontal and two nasal bones. Visible depression directly between the eys, superior to the bridge of the nose
33
What's the difference between Infraposition and Infraocclusion?
Infraposition: alveolar bone growth stops from ankylosed tooth (from trauma). Notably the gingival level is more apically placed Infraocclusion: tooth has not reached occlusal level
34
What 3 anatomical structures develop from Meckel's Cartilage?
1. Symphyseal cartilage: from Medial tip (portion closest to where two Md articulate) 2. Sphenomandibular ligament: from Mid portion 3. Malleus and incus: from Lateral portion
35
What preventative measures need to occur for an excessive overjet
Mouthguards worn during physical activity
36
How is leeway space eventually lost?
Mesial drift of the FPMs after the eruption of permanent canine and premolars
37
What tooth sizes are aesthetic in the anterior zone?
Decreasing size from the central > lateral > canine following the golden proportions
38
What is Foster and Hamilton Class I Occlusion?
Opposing 2nd molars are the same (flush) vertical plane in centric occlusion
39
What is Bolton's Discrepancy?
Insufficient/Excessive Mn vs Mx size ratio outside of normal
40
What is the main direction of tooth eruptive force?
Axial. Other planes of force can occur, resulting in tooth tilting/drifting
41
Which tooth is most likely to be ectopicly placed?
Upper canines
42
What are the cranial base synchondroses?
Cartilaginous Junctions between bones in the cranial base that allow for active growth via endochondral ossification.
43
Which facial profile occurs when the Vertical G’-Sn-Pog’ line slopes posteriorly with Pog posterior relative to glabella in sagittal plane?
Convex Profile (Posterior Divergence)
44
T/F: Men have a higher lip line then women
False, women tend to display 1-2mm more gingiva than males and this is more acceptable aesthetically
45
Where is Rhinion (R)?
R: Rhinion: junction of hard tissue nasal bone and septal cartilage
46
What does Cephalometric Superimposition require?
Time series of patient's Lat Ceph radiographs
47
What trends can be seen in growth curves between males and females?
Amplitude: males at a high rate Duration: males for longer Onset: females start earlier but don't grow as much
48
What should you expect to see clinically for permanent canines at age 10?
Developing tooth can be palpated on the buccal sulcus
49
Is Mandibular Prognathism likely to resolve without treatment?
No
50
Which finger is missing the intermediate phalanges?
Thumb
51
What are the 5 key sutures in the naso-maxillary complex?
``` Frontomaxillary Zygomaticomaxillary Pterygomaxillary Zygomaticofrontal (Indirectly) Zygomaticotemporal (Indirectly) ```
52
Which teeth are most likely to be transpositioned?
Maxillary 3 and 4
53
What features do you expect to see in a skeletal neutrocclusion (Class I)?
Overbite 20-30% Overjet 2-3mm Class I Canine Relationship Class I Molar Relationship
54
What are some weird trends in dental aesthetics?
Yaeba (snaggle teeth) proclined canines Diastemas (increased frequency in fashion) Cape Flats Smile - missing anterior maxillary due to violence. So gangsta Ritualistic Tooth Filing
55
According to Scammon's Growth Curve, which system peaks at 10 years and then declines?
Lymphoid
56
What should you expect to see clinically for permanent canines at age 12?
Indicative of late eruption - investigate clinically and radiographically whether the tooth is not present/impacted
57
Is a skeletal class II in a baby a concern?
Not really, mandibular growth will be faster than maxillary growth and in most cases compensate in late teens to 25. However check for familial skeletal patterns.
58
What is primate space?
Gap spaces in the arch of primary dentition
59
What are different types of growth estimation and which one is appropriate for growth estimation?
Skeletal Bone Ossification: marker of skeletal maturity during puberty growth spurts Dental: Tooth formation and emergence Age: deviations from medium Height: heavily influenced by environment/diet Weight: heavily influenced by environment/diet Sexual Maturity Neural Coordination - Not present in all people Neural Cognitive development - differences between sexes
60
Where is the Glabella (G)?
Soft tissue landmark - The smooth part of the forehead above and between the eyebrows
61
How can malocclusion be described in Angle's line of occlusion?
A tooth being either lingual/labial from the line of occlusion
62
What is the Ugly Duckling phase?
The transitory stage of dental development (7-12 years) before the eruption of permanent canines, when there is lateral tipping of incisors causing a “ugly appearance
63
What is a Angle's Class I Classification?
MB cusp of upper first molar is received in lower first molar buccal groove where there are malocclusion features such as crowding/rotation
64
What are the different types of forwards rotators?
Type I: Point of rotation around the condyle Result: reduced lower face height Type II: Point of rotation located at incisal edge of lower incisors Result: marked development of posterior face height and normal anterior face height Type III: Point of rotation at level of pre-molars Result Large overjet/reverse overjet Anterior face height underdeveloped Posterior face height increases with deep bite
65
What are the important stages of the Nolla Calcification Staging?
``` Stage 0: Absence of Crypt Stage 2: Initial Calcification Stage 6: Crown complete Stage 9: Root Complete, Apex Open Stage 10: Apical Foramen Closed ```
66
T/F: Growth of the cranial base is primarily due to growth of cartilage in the synchondroses
True
67
What features do you expect to see in a skeletal mesiocclusion (Class III)?
- Often prognathic Md, occasionally retrognathic Mx - Protruded Lower Incisors, Edge-to-Edge bite, Crossbite - Class III Canine Relationship Incisors - Class III Molar Relationship - Crowding/Spacing more likely in uppers - Constricted Mx Arch
68
Which facial profile occurs when the Vertical G’-Sn-Pog’ line slopes anteriorly, with Pog anterior relative to glabella in sagittal plane?
Concave Profile (Anterior Divergence)
69
T/F: A Maxillary expansion device is an example of a orthopaedic device
True - It is an orthopaedic device that impacts skeletal growth/shape with dental effects
70
Forwards Rotators result in what sort of face?
Short Face
71
What are 6 determining factors that shape the molar relationship?
1. Magnitude of step in terminal plane 2. Type of facial growth pattern e.g. horizontal and vertical 3. Amount of interdental spacing 4. Early loss of deciduous teeth 5. Any loss of arch length 6. Amount of Leeway space
72
When should eruption of primary dentition be complete?
2.5 - 3 years of age
73
What is the Bjork Classification?
A means of classifying the molar occlusion of 1st permanent molars
74
What are some psychosocial reasons that a person might consider orthodontics?
Variability from norm Appearance creates isolation, bullying Increased aesthetic norms
75
How much earlier do lower permanent canines erupt in females compared with males?
12 months
76
T/F: People of black ethnic origins will experience tooth eruption earlier than others
True
77
What are some examples of craniofacial deformities where orthodontics could be considered?
Cleft Lip + Palate Severe Accidents Patients with Syndromic Conditions Severe Class II/III patients considering Orthognathic Surgery
78
What determines the tooth positions of accessional molars?
1. Vertical alveolar growth 2. Maxilla: Posterior deposition in tuberosity region 3. Mandible: Resorption of the anterior border of Mandible - providing additional space in the dental arch
79
What are issues with Moyer's Analysis?
1. Premature Tooth Loss: secondary crowding, loss of arch space 2. Prolonged Tooth Retention: affects emergence time and direction, depends on which tooth and its position in the arch (ie lowers incisors) 3. Asymmetrical arches: affects midlines 4. Severity of Crowding/Spacing: access to contact points, harder to assess arch shape, need to account for midline diastema 5. Facial Pattern: influences arch size and shape, soft tissue pattern affects tooth position, apical base dimensions and position
80
What hormonal factors can alter dental development?
1. Increased maturity after menarche (first menstruation) | 2. Delayed development through hypothyroidism
81
How long can it take for an erupting tooth to reach the opposing dentition?
1-2 years
82
What is the difference between endomorph, mesomorphy and ectomorph body types?
1. Endomorph: Preponderance of Body Fat 2. Mesomorph: Predominance of muscle, bone and CT 3. Ectomorph: Preponderance of skinny and delicate build
83
What shape face might you expect with an Endomorph?
Square face: short and obese body type
84
What is the main reason for natal teeth?
Ectopic position of tooth germ in foetal life allows for early eruption
85
What is the difference between Baume Type I and II?
Baume type I (spaced): generalised spaces between primary teeth Baume type II (closed): primary teeth are proximal contact
86
What is secondary crowding?
Secondary Crowding is caused by environmental factors influencing the dentition, such as caries, extractions When teeth extracted, teeth drift forward if no space maintainers placed
87
What are some systemic factors that can delay tooth eruption?
``` Down’s syndrome Hypothyroidism Hypopituitarism Hypovitaminosis (A&D) Osteopetrosis Cleidocranial dysplasia Hereditary Gingival Fibromatosis Achondroplasia Amelogenesis Imperfecta Familial Patterns (Genetic) ```
88
What is the Symphyseal cartilage and when does it disappear?
Unites 2 halves of mandible at symphysis and ceases after 1st year of birth
89
What is the main reason for delayed eruption?
Insufficient space
90
What is Inter-Canine Width?
Horizontal distance between right and left canine cusp tips
91
Early intervention of Class II skeletal relationship will require what sort of orthodontic treatment?
Functional appliance Fixed Appliance Orthognathic surgery
92
What are the implications for standardising orthodontic treatment based on the combinations of Proffit's sagittal cranial diagram?
Every patient is unique: combinations of all skeletal + dental relationships is 3 power 12 = 531441 combinations
93
What is Dento-alveolar compensation?
Where tooth eruption and alveolar development will compensate for the apical base dimension if there are skeletal discrepancies. This will result in malocclusion seen in class II/III occlusions
94
What are the 3 orthodontic considerations for aesthetics?
1. Facial 2. Dentofacial 3. Smile: particular impact of extraction/non-extraction in treatment
95
What are 5 issues with measuring anterior + posterior segments to determine arch length discrepancy?
1. Partially Erupted Teeth give incomplete readings 2. Impacted Ectopic / Missing Teeth 3. Parallax error of calipers 4. Straight Line approach cuts off true arch length 5. Doesn’t take into account tooth displacement (eg rotation)
96
When is the most common period for lip incompetence
9-13 years and often resolves over puberty
97
Ossification of the mesenchyme and ectomesenchyme covering the developing brain is dependent upon influences from what tissue type?
Neural epithelium
98
What permanent teeth do we expect to see at age 7?
Upper 1s | Lower 2s
99
What are the 4 stages of Fisher’s Skeletal Maturity Indicators?
1. Width of Epiphysis = Width of Diaphysis 2. Ossification: Development of Adductor sesamoid of Thumb 3. Capping of Epiphysis 4. Fusion of Epiphysis to Diaphysis
100
What is the main determinant of tooth position of successional permanent teeth?
The position and resorption patterns of primary teeth
101
What are issues with appliances that are left on for too long?
Issues with poor OH Major Tooth Resorption Loss of periodontal attachment
102
What are the 5 growth sites in the cranial base?
``` Foramen magnum (apposition at Ba) Spheno-occipital synchondrosis (endochondral growth) Spheno-ethmoidal synchondrosis (endochondral growth) Fronto-ethmoidal suture Frontal bone (surface apposition) ```
103
What are considered Mini Aesthetics when assessing a patient?
Tooth Lip Relationships - Midline Relationship - Maxillary Cant - Incisal Display ``` Smile Analysis (Static/Dynamic) Incisal Display Gingival Display Buccal Corridors Smile Arc ```
104
T/F: Coronoid cartilage is present at birth
False - Coronoid cartilage is a strip along the anterior border of the coronoid notch that disappears before birth
105
What are the progenitor cells for Meckel's Cartilage?
Ectomesenchymal (neural crest) origin
106
What is Incisor Liability?
Difference between the mesial-distal diensions of the permanent incisors vs the primary incisors
107
What does Powell's Naso-Facial Angle (G-Pog to N-NT) tell us?
Range: 30-40 | Decreased Angle = Skeletal Prognathic Mandible
108
Which facial profile occurs when the Vertical G’-Sn-Pog’ line is parallel to the true vertical line?
Straight Profile (Natural Divergence)
109
What is most common terminal plane relationship in children?
Flush terminal plane.
110
What is impaction?
Failure of a tooth to reach its normal position by bone, tissue or another tooth
111
What are 3 possible outcomes of arch length discrepancy measurements
Spacing Perfect alignment Crowding
112
According to Ackermann-Proffit, how can alignment be described?
Ideal Crowded Spaced Mutilated
113
What is Bolton's Analysis?
Determine the compatibility / discrepancy between size of maxillary and mandibular teeth. This helps determine the ideal interarch relationship
114
What is the Ackerman-Proffit Classification ?
Describing the skeletal relationship between the maxilla and mandible
115
What are deficiencies in Angle’s Classification?
Static Description Molar relationship could change No reliable indication of underlying skeletal pattern No functional indication of how jaw works No soft tissue description (tongue, lips, gingiva) No vertical or transverse description
116
What is Bjork Class I Occlusion?
Class I Occlusion - Normal, or at most one-half cusp postnormal or prenormal
117
What accounts for the lowering growth position in the naso-maxillary complex?
Resorption at orbital and nasal floors | Deposition along hard palate
118
What is the BSI Incisor Class I?
Cingulum Plateau of Mx Central Incisors occludes with the opposing Md incisal edge
119
What is the growth direction the naso-maxillary complex?
Displacement downwards and forward
120
What accounts for the forwards growth position in the naso-maxillary complex?
Soft tissue development in the mid-face region
121
What are signs of poor oral hygiene in a orthodontic patient?
Decalcifiction of buccal surfaces
122
Does mandibular forward/backwards rotation itself cause malocclusion?
No - as there is dentoalveolar compensation to a point Malocclusions such as deep overbite or anterior open bite occur when the dentition is unable to compensation for severe rotation
123
What are examples of bite depth (vertical relationship) in Ackermann-Proffit?
``` Anterior Open Bite Posterior Open Bite Anterior Deep Bite Posterior Collapsed Bite Dental Skeletal Combined Skeletal and Dental ```
124
T/F: Functional appliance are responsible for growing the jaw.
False - as it doesn't work on an adult. It creates an optimal environment for growth during the peak growth phase
125
How do permanent incisors fit during eruption?
1. Residual spacing between deciduous incisors 2. Labial Eruption Path: permanent incisors erupt into more labial position (esp. in Mx) and occupy a greater arch perimeter 3. Deciduous canines move distally into primate spaces as incisors erupt 4. Transverse increase in intercanine arch width
126
What is contained within the apical base?
1. Crowns of the Teeth (Both erupting + developing) | 2. Roots of the Teeth
127
T/F: Proportionally the combined growth of upper + lower lips exceeds LAFH
True
128
What is supraocclusion?
When a tooth has erupted past occlusal level (overeruption)
129
Why is incisor relationship important?
Clinically relevant as it is a truer reflection of skeletal base relatinoship
130
What is the shedding order of primary teeth?
Same as eruption: ABDCE
131
Which part of the nose grows in size?
The septal cartilage
132
What is Interceptive Orthopaedics and when can it be conducted?
Any procedure that reduces the severity of malocclusion in the adult dentition (ceasing of parafunction, extractions, movement of teeth) - up to 11.
133
What are limitations of Angle's classification?
1. Can’t use if there are absent FPMs 2. Does not differentiate molar relationships between both sides of mouth 3. Does not specify the magnitude of discrepancy (especially crowding/OB/OJ) 4. Does not specify skeletal or facial patterns
134
What are the 5 components of Proffit's sagittal cranial diagram?
Cranial Base > Maxilla > Maxillary Dental Base > Mandibular Dental Base > Mandible
135
Describe what happens to forward rotators?
Mandibular Rotation axis is upwards and forwards around the most distal occluding molar, shortening the face
136
What are risks of orthodontic treatment?
1. Small Loss of periodontal attachment 2. Root resorption: may be significant in susceptible people 3. Poor OH
137
Where is the Nasal Dorsum (Nd)?
Soft tissue landmark - the visible hump along the bridge
138
What diagnostic records are helpful in orthodontic diagnosis?
1. Intraoral Radiographs (OPG, B/W, PA, Lat Ceph) 2. Study Model Casts (Occlusion, Space Analysis) 3. Extra Oral Photos (Frontal/Profile/Smile/Lips)
139
Is complete symmetry an aesthetic quality?
No: full symmetry appears weird to the human eye, but beauty is often judged by the lack of gross asymmetry
140
What trends occur in Inter-Canine Width between 12-18 years?
Md: Decrease 1-2mm after eruption of 3s until age 45 → late lower incisor crowding Mx: Increase 1-2mm after eruption of 2s until age 45
141
What is Crouzon Syndrome?
Sporadic / Autosomal Dominant gene disorder: Craniosynostosis: Characterised by premature fusion of multiple sutures from an early age Leads to: ``` Craniosynostosis Brachycephaly (wide face) Ocular proptosis (bulging eyes) Midfacial malformation (Mx hypoplasia => dental crowding) Class III occlusion Conductive hearing loss ```
142
What are the different types of backwards rotators?
Type I: Point of rotation about the condyle, resulting in an increased anterior face height Type II: Point of rotation around the most distal occluding molar
143
What is the cephalocaudal gradient?
Growth potential is greater in structures more distant from brain, but structures close to brain complete development sooner than those more distant
144
What is considered aesthetic in regards to buccal contours (negative space)?
Minimal empty space to give smile a broad appearance (think Julia Roberts)
145
What is the main treatment for Open Bite?
Identifying aetiology and ceasing the parafunctional habit that caused it
146
What is a Euryprosopic facial type?
Broad face type when referring to extra-oral features
147
Describe what happens to backwards rotators?
Mandibular Rotation axis is on condyle going posteriorly, leading to lower face becoming longer
148
What features do you expect to see in a skeletal distoclusion (Class II Div 1)?
- Often retrognathic Md, occasionally prognathic Mx - Proclined Incisors - Full Unit Class II Canine Relationship - Full Unit Class II Molar Relationship - Overbite: Open to Deep, Possibly Traumatic - Arch Shape: V shaped - Variable crowding/spacing
149
What occlusion type are overbites most commonly found?
Class II Div II
150
What are factors that influence growth and development?
``` Genetics Neural control Hormones Nutrition Disease Socio-economic status Season/climate Exercise Secular trends Emotion ```
151
Where is the Labiale Superior (Ls)?
Soft tissue landmark - Point denoting vermilion border of upper lip
152
Where is the Labiale Inferior (Li)?
Soft tissue landmark - Point denoting vermilion border of lower lip
153
What is rotation?
When a tooth has been rotated around it's long axis. Often congenital.
154
T/F: Excessive overjet increases the risk of dental trauma
True, makes fracture/avulsion of teeth from physical force injuries / falls more probable
155
What time of day correlates with eruption?
8pm- Midnight: governed by circadian rhythm and growth hormones
156
Where can primate spaces generally be found?
Md is usually mesial to the C | Mx usually distal to the C
157
How many bones are there in the carpels?
8
158
When will malocclusions occur?
Where there is a lack of dento-alveolar compensation from a lack of facial and alveolar growth to accommodate permanent dentition
159
What is Rickett’s Esthetic Plane (E-Plane)?
Soft tissue assessment that gauges lip position from a line drawn from pronasale and soft tissue pogonion (ST Pog) (tip of nose to chin)
160
What is Orthodontic Camouflage and when can it be conducted?
After peak growth (11+), only changes to teeth to mask an underlying skeletal discrepancy
161
What directions does the chin grow?
1. Anterior aspect of mandibular alveolus at symphysis is resorptive 2. Bottom Chin at mandibular border is additive
162
The cranial vault is comprised of which bones?
Frontal Temporal Occipital Parietal
163
What are issues with the Greulich and Pyle Atlas as a predictor of skeletal age?
Index is decades old No consideration of genetic/ethnic differences No consideration of environmental factors that can stunt/accelerate growth (starvation, nutrition)
164
What factors can affect growth rate?
``` Normal variation Hereditary factors Birth weight Nutrition Behavioural/social development ```
165
Which grows faster - maxilla or mandible?
Mandible
166
What chin types are consider most unaesthetic?
Severe class II or III
167
What does Powell's Naso-Mental Angle (N-NT to NT-Pog) tell us?
Range: 120-132 | Decreased Angle = Skeletal Retrognathic Mandible
168
According to the Cephalocaudal Gradient, which structure is the most developed at birth?
Head and Neck
169
Heavy abrasion/attrition from Indigenous diets resulted in what changes to malocclusion ?
Interproximal attrition > Mesial Movement + Early eruption of 3rd molars > Elimination of milder malocclusion. Tendency to: - Mesial movement into Class III Occlusion - Edge to edge bite - Flattened curve of spee - Reduced dental arch length
170
What does Powell's Facial Profile tell us?
Broad line to work out of facial profile is straight, convex or concave
171
Should avulsed primary teeth be implanted again?
No - as risk of ankylosis means that this could prevent permanent teeth from erupting
172
Where is the Menton (Me)?
Soft tissue landmark - Lowest point on mandibular symphysis
173
What are several methods to estimate arch length discrepancy?
1. Measuring Anterior + Posterior Segments 2. Arch form analysis (using Nitinol arch wire) Both methods measure individual M-D tooth width then compare cumulative tooth widths to arch length
174
What permanent teeth do we expect to see at age 18-24?
Upper and Lower 8s
175
What relationship should there be for good aesthetics in contacts?
Teeth should be in contact
176
What features do you expect to see in a skeletal distoclusion (Class II Div 2)?
- Often retrognathic Md, occasionally prognathic Mx - Retroclined Incisors - Full Unit Class II Canine Relationship - Full Unit Class II Molar Relationship - Overbite: Open to Deep, Possibly Traumatic - Arch Shape: Broad and flattened anteriorly - Variable crowding/spacing
177
What shape face might you expect with an Ectomorph?
Long and Lean face: tall and long body type
178
What are limitations to eruption counts in calculating dental age?
1. Unerupted Teeth (Agenesis/Impaction) 2. Tables only go up to 16 years 3. Accelerating/Delaying Factors (Ectopic Position, Insufficient space, retained primary roots)
179
T/F: Malocclusions can alter the perception of individuals with their peers and teachers
True, but characteristics that have positive/negative weightings are highly variable depending on age, gender, culture, relationship type (peer, authority, teacher)
180
What cellular growth occurs during post-natal growth?
Cell and matrix increase
181
What defines a scissor bite?
when one or more adjacent posterior teeth are completely buccal/lingually to the opposite teeth and display a full vertical overlap
182
What cranial shape is Brachycephalic ?
Short-wide head: horizontally shorter and transversely wider
183
Where is the A Point?
Soft tissue landmark - the most concave point of the anterior maxilla
184
T/F: Growth of the maxilla is a combination of soft tissue matrix and cartilage
True
185
What are features of forwards rotators?
Flattens occlusal plane Increased Overbite Lower Incisor Crowding with age Slow space closure
186
T/F: Facial growth can continue slowly for decades?
True. Growth can happen in: Tooth eruption Nose growth Ear enlargement Condyles and chin
187
How does Nolla Calcification Staging work in calculating dental age?
Measure the development of a tooth radiographically against 10 stages to gauge maturity. The tooth is then plotted against statistical averages for Mx/Mn arches to determine the dental age. Overcomes issues with crowding/delayed eruption. More indicative of true growth and development
188
How are Growth and Development different?
Growth: An increase in tissue size Development: An increase in tissue organisation and specialisation
189
Why do individuals decrease in height in old age?
Joint Compression and Vertebral degeneration
190
What are methods measuring bone ossification?
Hand Radiographs that are referenced between different growth scales: 1) Greulich and Pyle Atlas - measuring development of carpal bones, distance between bones and development of hamate 2) Fisher’s Skeletal Maturity Indicators - Evaluating development and fusion of epiphysis in fingers
191
What permanent teeth do we expect to see at age 9?
Upper 4s
192
Which is more common, backwards or forwards rotators?
Forwards = 80% of population
193
What is the difference between Tipping and Displacement?
Tipped: apex normally placed but crown incorrectly positioned Displaced: apex and crown incorrectly positioned
194
What are the aesthetic qualities when displaying a lip line when smiling?
On smile: full crowns of maxillary Incisors + 1-2mm of gingiva visible during smiling
195
What is the zone of equilibrium?
The tooth position post eruption that is influenced by soft tissues and oro-facial function. This is the same as the neutral zone in occlusion
196
Which part of the face keeps grows the most rapidly?
The Nose
197
Which part of the nose is responsible for change of shape during growth?
Proliferation of lateral cartilage
198
What is Bjork Class Prenormal Occlusion?
Class III Occlusion - where the mandibular 1st molar is more than one-half cusp anterior of pre-normal relation
199
What molar relationship is likely to occur for a Class II Flush Terminal Plane?
Likely Class II Molar
200
What permanent teeth do we expect to see at age 10?
Lower 3s, Lower 4s
201
When should orthodontic treatment be started?
1. When all permanent dentition has erupted (most cases) | 2. Early Teens
202
What is possible to manipulate during active facial growth?
- Tooth Eruption | - Change direction to better utilise growth
203
What is the apical base?
The portion of the jawbone that give support to the teeth
204
What permanent teeth do we expect to see at age 6?
Upper and Lower 6s | Lower 1s
205
Should natal teeth be extracted?
No - could damage other tooth germs
206
Which facial profile has posterior divergence?
Convex Profile
207
Which facial profile has anterior divergence?
Concave Profile
208
What cranial shape is Mesocephalic?
Average head in proportion
209
What accounts for the increase in width of the naso-maxillary complex?
Growth at mid-palatal suture
210
What molar relationship is likely to occur for a Class I Flush Terminal Plane?
Likely Class I Molar
211
What is the terminal plane relationship?
The terminal plane relationship of primary second molars determines the amount of leeway space that is available for permanent premolars and canines. I can be used to predict the occlusion relationship in the permanent dentition.
212
What indications are there to start orthodontic treatment when there is late mixed dentition?
``` Ectopic 3s Poor quality 1st Molars (FPM) Infraocclusion Hypodontia Traumatic overbite Increased overjet ```
213
What does Powell's Mento-Cervical Angle (G-Pog to C-Me) tell us?
Range: 80-95 | Decreased Angle: Longer Facial Height, Backwards Rotator
214
What is the eruption sequencing of primary dentition?
ABDCE
215
What are limitations to Nolla Calcification Staging in calculating dental age?
- Requires OPG to make assessment | - Somewhat subjective measure
216
What contributes to a small level of height growth in individuals from 20-30?
Deposition of bone on the vertebrae
217
Why is skeletal bone ossification a good marker for orthodontic planning?
Determines onset of growth spurt that corresponds with orthopaedic changes - this can reduce treatment time. However this needs to be considered with the level of dental maturity as well
218
Where is the Columella (Cm)?
Soft tissue landmark - the tissue that links the nasal tip and nasal base - on the inferior margin of the nasal septum
219
Where is the B Point?
Soft tissue landmark - the most concave point of the mandibular symphysis
220
What are the clinical implications of residual meckle's cartilage?
Transmigration of mandibular canines
221
If a tooth's gingival margin is considerably lower than the rest of the arch, is it infraocclusion or infraposition?
Infraposition: failure of the alveolar bone to keep growing due to trauma from ankylosed tooth. The gingival margin on a infraocclusion tooth will be in line with the rest of the arch
222
What sort of chin is considered most attractive
Ideal sagittal position of ST Pog is on or just behind true vertical line through subnasale.
223
What are cranial vault sutures comprised of?
Connective Tissue that allow for intramembranous ossification that is reactive to tension provided at the margins
224
What are landmarks for Cranial Base Superimposition?
1. Sella Turcica (anterior wall of pituitary fossa 2. Lamina Cribrosa (Contour of cribriform plate of ethmoid) 3. Trabecular outline of Ethmoid Air Cells 4. Medial Border of Orbital Roof 5. Plane of Sphenoid 6. Greater wings of sphenoid
225
What is tertiary crowding?
Tertiary Crowding occurs occurs in post-adolescent period and is a normal part of the aging process. This will occur naturally without the use of fixed/removal retainers
226
What are buccal contours (negative space)?
Space between the buccal surface of the posterior teeth and commissures during smiling
227
T/F: Class I/II/III in the Foster Classification correspond with the Bjork Classification
False, as Foster describes primary molars, Bjork describes FPM
228
What cranial shape is Dolichocephalic?
Long Head: horizontally long and transversely narrow (<75% H:W ratio)
229
What are the limitations of Bolton's Analysis?
1. Bolton’s sample size for relationships was white caucasian only 2. Sample group only had perfect malocclusions Therefore its likely that most people will fall outside of normal
230
What has happened to the condylar cartilage by 5 months in utero?
Most of the condylar cartilage has ossified except narrow cap beneath articular surface of condyle
231
Is Anterior Open Bite likely to resolve without treatment
No, if related to skeletal problems and not parafunction
232
What are 4 different types of direct measurements for growth?
1. Anatomical Measure 2. Secondary Sexual Characteristics 3. Lateral Cephalometry 4. 3D finite element model 5. MRI 6. CT Scanning
233
Which grows faster - facial region or vault of skull
Facial Region
234
What 2 mechanisms allow for post natal growth of the mandible?
1. Bony remodelling via subperiosteal resorption and deposition 2. Cartilaginous growth at condyle
235
What are features of backwards rotators?
Increased Anterior Face Height Long Face Class II Skeletal Relationship Reduced Overbite
236
What does Powell's Naso-Frontal Angle (G-N-NT) tell us?
Range 115-130 Decreased angle = Skeletal Prognathic Maxilla
237
What are issues with natal teeth?
Likely to be mobile due to limited root development
238
What is a pseudo Class III?
When there is a premature contact in central relation, the patient must protrude mandible forward to clear contact. This gives the illusion of Class III Resolution - remove premature contact
239
What would be the cause of a Straight smile arc?
- Incorrect Orthodontic positioning of incisal edges | - Age related tooth wear
240
Where is the Pronasale (Pn)?
Soft tissue landmark - the point of the angle between the septum of the nose and the surface of the upper lip, found at the point where a tangent applied to the nasal septum meets the upper lip.
241
What 6 factors hamper ideal dental alignment?
1. Lack of interdental, primate and leeway spaces 2. Reduction in dental arch length after permanent incisors erupt 3. Dento-alveolar disproportion 4. Early loss of primary teeth 5. Soft tissue 6. Oral habits
242
What is Bimaxillary Protrusion?
When both jaws are protrusive → protrusion of Mx and Md in relationship to the Anterior Cranial Base
243
What are the 9 Ackermann-Proffit groups?
Group 1: Alignment Problems Group 2: Alignment, Profile Problems Group 3: Alignment, Profile, Transverse Problems Group 4: Alignment, Profile, Sagittal Problems Group 5: Alignment, Profile, Vertical Problems Group 6: Alignment, Profile, Transverse and Sagittal Problems Group 7: Alignment, Profile, Sagittal and Vertical Problems Group 8: Alignment, Profile, Transverse and Vertical Problems Group 9: Alignment, Profile, Transverse, Sagittal and Vertical Problems
244
What is Angle's line of occlusion?
Shows how teeth should normally occlude: Incisal edges and buccal cusps of the Md arch coincide with the cingulum of the incisors and canines plus the premolar and molar fossae in the Mx arch
245
What are the most common natal teeth?
31, 41
246
What are problems with ectopic teeth?
Can caused root resorption of impacted teeth if not treated
247
What are the pre-emergent tooth positions of successional canines?
1. Maxillary canines start below the floor of the orbit (hence eye teeth) 2. Located between the roots of the 1st primary molar (D) 3. Erupt distal and lingual to primary canines
248
According to Proffit, what are the 3 main orthodontic issues?
1. Crowing/Protrusion = psychosocial handicap 2. Malocclusion = functional handicap (AOB/Supereruption) 3. Malocclusion = increased risk of pathology (crowding => caries/perio)
249
What is the BSI Incisor Class II Div I?
Lower incisor edges lie posterior to the cingulum plateau of the upper incisors and the incisors are proclined
250
What is Foster and Hamilton Class II Occlusion?
Distal surface of lower 2nd molar in posterior relationship to that of upper 2nd in centric occlusion
251
What relationship should there be for good aesthetics in gingival contours?
Central incisors and canines: Gingival margins should be level Lateral Incisors: should like 1mm more incisally
252
What is Orthognathic Surgery and when can it be conducted?
Surgery changes to the craniofacial skeleton conducted after peak growth (13+) so that changes won’t be undermined by continued facial and skeletal growth
253
What are natal teeth?
Natal teeth are teeth that are present above the gumline (have already erupted) at birth
254
What are the pre-emergent tooth positions of successional incisors?
Permanent teeth lingual to primary teeth
255
What drives the growth of the surface area of the cranial value?
Displacement of bone by growth of the brain and osteogenesis at the sutural margins
256
What can be seen by Cephalometric Superimposition?
1. Completion of Cranial Base Growth 2. Maxillary growth/rotation from development + orthodontic treatment 3. Maxillary growth/rotation from development + orthodontic treatment
257
T/F: Growth of the cranial vault occurs largely by growth at the sutures and surface remodelling and is primarily due to growth of the brain
True
258
Where is the Gnathion (Gn)?
Soft tissue landmark - Point located perpendicular on mandibular symphysis midway between pogonion and menton
259
T/F: Molar Angle's Classification is congruent with skeletal relationship
No
260
T/F: The nose continues to grow after skeletal growth finishes
True
261
What relationship should there be for good aesthetics in connectors?
Connectors decrease as you move posterior
262
The Cranial Base comprise of which bones?
Frontal Ethmoid Sphenoid Occipital
263
What are considered Micro Aesthetics when assessing a patient?
The appearance of dentition: Tooth Proportions Width Relationships (Golden proportions: 62% each size tooth distally) Height / Width Relationship (80%) Gingival Height, Shape and Contour Connectors (interdental contact area): becomes smaller moving distally Embrasures Tooth Shade and Colour
264
What is crowding?
Discrepancy between tooth size and jaw size (apical base) that results in the misalignment of teeth
265
What developmental feature in the hamate bone is part of the Greulich and Pyle atlas?
Hamate develops an exostosis perpendicular to the open palm during puberty and is clinically visible as a radiopaque density on a hand radiograph
266
What accounts for the increase in height of the naso-maxillary complex?
Sutural growth at zygomatic and frontal articulations | Deposition at alveolar processes
267
When does the Ugly Duckling phase resolve
Once the full compliment of Maxillary anteriors has erupted.
268
How can overbite be described
``` Open (Anterior Open Bite) Reduced Average Increased (complete) Increased (traumatic - against palate) Increased and incomplete (likely severe Class II Div 1) ```
269
What is tooth eruption?
Process whereby a tooth moves from its developmental position in the jaw into its functional position in the mouth
270
What is the calcification order of primary teeth?
ADBCE
271
T/F: Proportionally Lower Lip Growth exceeds Upper Lip Growth
True
272
What are the 3 types of smile arcs?
Consonant Straight Non-Consonant
273
What are the 2 means of craniofacial growth?
1. Sutures | 2. Surface Remodelling
274
T/F: Growth of the mandible is due to soft tissue matrix
True
275
What is leeway space?
The Difference between C - E and the 3-5
276
What is Dentofacial Orthopaedics and when can it be conducted?
Guidance of facial growth and development to achieve skeletal changes (eg functional appliances and headgear). Needs to occur before peak growth (up to 13)
277
The face is comprised of what 2 elements?
Naso-maxillary Complex | Mandible
278
What indications are there to start orthodontic treatment when there is early mixed dentition?
``` Non nutritional sucking behaviour Delayed Eruption Financial Reasons Early Loss of Primary Teeth First permanent molar impaction Crossbites Severe Crowding Increased Overjet ```
279
What is transposition?
2 teeth that have switched position
280
What are indirect anatomical measures that could be used for measuring growth and development?
1. Indirect measurements: Biologically Active Agents (Tetracyclines, Alizarin, Procion Dyes) 2. Histology (LEM, Radioisotope Labels, Histochemical markers)
281
What is the Suture theory of craniofacial growth and why is it not current dogma?
Bones are pushed apart as a result of pressure created by active growth at the sutures growth centres. Debunked: Transplanted sutures fail to grow. Growth inhibited when sutures are compressed
282
How does Hereditary gingival fibromatosis affect tooth eruption?
Thick gingiva slows eruption times
283
When would you ignore the golden proportion in the aesthetic anterior zone?
If there is insufficient space in the arch.
284
Which malocclusion is more likely to have lip incompetence?
Class II Div I
285
In terms of cervical vertebrae maturation staging, which stage is indicative of the optimal phase to start orthodontics
CS3: concavities on the lower borders of C2 / C3
286
What are the implications of Bolton's Discrepancy?
1. Aesthetic disproportions of upper vs lower dentition | 2. Impact of Occlusion relationship, interdigitation and function
287
What should you expect to see clinically for permanent canines at age 11?
Eruption into the oral cavity
288
When describing a crossbite, which tooth do we reference as being out of alignment?
The Maxillary Tooth involved in the crossbite
289
What is Foster and Hamilton Criteria?
A means of classifying the molar occlusion of primary second molars in centric occlusion
290
What is a main reason for prevention of eruption of a permanent tooth?
Failure of superior primary tooth to undergo root resorption.
291
What is the Golden Relation and where can it be used?
Ideal Proportions (1:1.618) that are judged by human eye as comforting/pleasing - Crown width/height - Soft Tissue Relationships - Hard Tissue Relationships (OMFS/Plastic Surgery)
292
What changes to the nose occur during peak growth period?
1. N angulation can change by 30% 2. Dorsum can lengthen by 1 mm/year 3. Columella depth may change by 0.5mm/year
293
How can the presence of bimaxillary protrusion be measured?
When SNA > 81, SNB > 78 but ANB is still within 3±2
294
What is the role of the general dentist in orthodontic treatment?
``` Detect Anomalies Early Oral Hygiene Monitoring Orthodontic Extractions Restorative Treatment Route Dental Checkups ```
295
What is Ackerman-Proffit Skeletal Class I?
Mx 2-4mm anterior to Md
296
Backwards Rotators result in what sort of face?
Long Face
297
What are the different incisal relationships in Angle's Classification?
Class I (Mn into Mx cingulum plateau) Class II Div 1 (Mx incisor proclined, occlusion more posterior) Class II Div 2 (in cingulum plateau, Mn incisor retroclined) Class III (Mn incisor in Mn cingulum plateau)
298
T/F: Lip Line decreases with age
True - you would then expect to see less gingiva exposed in the lip line on older people
299
T/F: High irregularity does not necessarily mean crowding
True Tipping irregularity can be related to soft tissue, NNSH Often crowding related to skeletal deficiency to dentition
300
How does eruption count work in calculating dental age?
Compare number of emerged permanent teeth against gender + Mn/Mx defined statistical averages to gauge dental age
301
What broad categories are there for nasal types?
In the nasal index: 1) Narrow (European): Type 1-5 2) Medium (Oriental): Type 6 3) Broad (African/Islander): Type 7-8
302
What are the 2 key structures in the mandible develop from the 1st Pharyngeal Branchial Arch?
Meckel's Cartilage | Inferior Alveolar Nerve
303
What are possible effects of crossbites?
Proclined incisors, dehiscence, loss of bone of labial aspect of root, can lead to loss of tooth
304
What is the BSI Incisor Class III?
Lower incisor edges lie anterior to the cingulum plateau of the upper incisors
305
What are direct anatomical measures that could be used for measuring growth and development?
1. Height Z-Scores and Percentiles 2. Weight for Age 3. Body Component Size/Ratios (Head/Arm circumference for age)
306
Where is the Subnasale (Sn)?
Soft tissue landmark - the point where the nasal septum merges with the upper lip
307
What is a Leptoprosopic facial type?
Tall, Narrow face type when referring to extra-oral features
308
What are the 4 phases of growth in life?
1. Embryo (essentially increase in size) 2. Foetus → adult (specialisation) 3. Adult (maintenance) 4. Old age (deterioration)
309
T/F: Chin retrusion or protrusion up to 4 mm is essentially unnoticeable in terms of aesthetics
True
310
T/F: 3rd Molars contribute towards tertiary crowding
False: no evidence as same rates of late crowding occurs in individuals with missing 8s
311
What is the eruption sequence of permanent dentition
Maxillary: 6, 1, 2, 4, 3, 5, 7, 8 Mandibular: 6, 1, 2, 3, 4, 5, 7, 8
312
According to the Cephalocaudal Gradient, which structure has the most development potential at maturity?
The Trunk
313
What are considerations for a growing facial profile?
1. A well balanced profile before puberty may deteriorate 2. Nose + Chin Lengthen 3. Lips become more retrusive + less full with time 4. Anticipate nose, chin and lip growth as part of orthodontic planning/treatment
314
What defines a crossbite?
A malocclusion where one or more teeth is more buccally/lingually placed to its antagonist tooth
315
What molar relationship is likely to occur for a distal step?
100 % Class II Molar
316
What can create Bolton's Discrepancy?
1. Developmentally Bigger Teeth: macrodontia, fusion 2. Developmentally Smaller Teeth: microdontia 3. Agenesis/Extracted Teeth Supernumeraries/morphological disharmony (eg peg lateral)
317
What non epiphysis indicators are present in the 11 stages of Fisher’s Skeletal Maturity Indicators?
1. Ossification of the Adductor Sesamoid in the thumb (Stage 4) 2. Fusion of the Radius (Stage 11)
318
What are the 4 cranial base synchondroses?
1. Fronto-ethmoidal 2. Spheno-ethmoidal (ossified by 7 years of age) 3. Inter-sphenoidal 4. Spheno-occipital (closed by 13-15 years in females, 15-17 in males)
319
What contributes most to vertical face height increase?
Tooth eruption and alveolar bone production
320
What is the technique for Maxillary Superimposition?
1. Align the maxillary outlines along the oblique line drawn tangent to the anterior contour of the zygomatic process 2. Move the overlapping line so that the bony apposition on the orbital floor is equal to the resorption in the nasal floor
321
T/F: Intramembranous ossification in load bearing areas?
False Intramembranous ossification occurs in non-load bearing areas such as the cranial vault, maxilla and mandible By comparison - endochondral ossification occurs in load bearing areas with cartilaginous pre-cursors: Long bones, Cranial base, Mandibular condyle
322
What are the 2 steps of eruptive movement?
1: Resorption of bone and/or primary tooth roots overlying crown of erupting tooth 2: Eruption of tooth through “resorbed” path
323
What 3 factors can result in growth?
``` Cellular Hypertrophy (size) Cellular Hyperplasia (number) An increase in extracellular volume ```
324
What environmental factors can change the nasal septum?
1) Rhinoplasty 2) Saddle Nose: cocaine use/trauma cutting blood supply from nasal septum - destroying tissue 3) Deviated Nasal Septum: physical trauma, breathing tubes during surgery
325
What permanent teeth do we expect to see at age 12?
Upper and Lower 7s
326
What are some local factors that can delay tooth eruption?
1. Absence of Teeth 2. Crowding 3. Delayed exfoliation of primary predecessors 4. Impaction 5. Ankylosis (from trauma to primary teeth) 6. Arrested tooth formation (trauma) 7. Cysts, tumours 8. Sclerotic bone 9. Abnormal position of Dental Crypts 10. Failure of eruption of primary teeth or permanent teeth 11. Dilacerations (roots physically stop tooth from erupting)
327
What are the overlapping categories in Ackermann-Proffit?
Tran-Sagittal Sagitto-Vertical Vertico-Transverse Trans-Sagitto-Vertical
328
The cranium is comprised of what 2 elements?
Calvarium (Cranial Vault) | Cranial base
329
What is a Angle's Class I Div II Classification?
Retrusion of lower jaw, with distal occlusion of the lower molar distal to upper molar where the central incisors are retroclined
330
What is Arch Circumference?
Distance measured round the arch from the mesial contact of 1 FPM to the mesial contact of the other FPM
331
What are the 3 arch change directions that occur between 6-12 years of age?
1. Vertical: increasing facial height 2. Anterior-Posterior (Mesial/Distal): creating room for permanent molars 3. Transverse (1-1.5mm after 8 years)
332
What shape face might you expect with an Mesomorph?
Proportioned face: robust, athletic with broad shoulders
333
What are considered Macro Aesthetics when assessing a patient?
``` Development Age Front Analysis (Symmetry, Horizontal 3rd, Transverse 5ths Profile Analysis (Convex, Straight, Concave) Facial Type (Brachy, Dolicho, Meso) Facial Features (Chin Prominence, Length of Face, Competence of lips) ```
334
What should be clinically observable dentally at 2.5-3 years of age?
1. Eruption of primary dentition complete 2. Modest increases in arch width and circumference 3. Vertical eruption continues + development of alveolar bone 4. Subtle malocclusions detectable (Class II parafunction, tooth chipping from trauma, non-evulsed teeth, deep overbites)
335
What is the post-emergent spurt?
The rapid eruption of a tooth as it enters the oral cavity
336
What's the implication of the Gnomic Growth pattern on orthodontic treatment?
Growth Directions is dependent on underlying skeletal morphology - so without treatment the underlying skeletal pattern is not expected to change on average even with growth
337
What trends occur in arch circumference between 12-18 years?
Mx: remains about the same, small increase in males Md: Decrease significantly between 5-18 years
338
When does a tooth first start to erupt?
Once the root begins to form?
339
According to Scammon's Growth Curve, which system grows the fastest from birth, plateauing around 10 years?
Neural
340
What are the 2 main indications for orthodontics?
Aesthetics | Function
341
What is the BSI Incisor Class II Div II?
Lower incisor edges lie posterior to the cingulum plateau of the upper incisors and the incisors are retroclined
342
What is aesthetics?
A set of principles concerned with the nature and appreciation of beauty
343
T/F: Deep bites will resolve somewhat after the eruption of the second molars
True: Second molars increases the bite
344
What cellular growth occurs during pre-natal growth?
Cell division and specialisation
345
What direction does the mandible grow?
Mandible grows upwards and backwards to maintain contact with cranial vault (at TMJ) Upwards: Condylar growth via endochondral ossification Backwards: Intramembranous ossification on posterior border of the ramus Remodelling that helps maintain shape/proportions of bone as it increases
346
What permanent teeth do we expect to see at age 8?
Upper 2s
347
What is a Angle's Class III Classification?
Protrusion of lower jaw with mesial occlusion of the lower teeth, with lower incisors and cuspids inclined lingually
348
What is a normal angle classification?
MB cusp of upper first molar is received in lower first molar buccal groove
349
How many phalanges bones are present on one hand?
14: 5 Distal, 4 Intermediate, 5 Proximal
350
How does Cleidocranial Dysplasia affect tooth eruption?
Teeth develop but don't erupt
351
What are aspects of aesthetics in the transverse plane?
- Evenness in transverse fifths
352
What is Inter-Molar Width?
Horizontal distance between right and left central fossae of upper and lower FPMs
353
What is a Angle's Class II Div I Classification?
Retrusion of lower jaw, with distal occlusion of the lower molar distal to upper molar where the central incisors are proclined
354
What is Powell's Soft Tissue Profile Analysis and what can it measure?
Assesses soft tissue profile balance and harmony ``` Facial Profile (G-Pog and FH) Naso-Frontal Angle (G-N-NT) Naso-Facial Angle (G-Pog to N-NT) Naso-Mental Angle (N-NT to NT-Pog) Mento-Cervical Angle (G-Pog to C-Me) ```
355
What would you find in a 1/2 unit class II occlusion
Retrusion of lower jaw where the mandible has moved back half a pre-molar width. Canines would typically be cusp tip-to-tip
356
What is Moyers Mixed Dentition Analysis (Michigan Analysis) used for?
Determine whether there is sufficient space for the unerupted buccal teeth (3,4,5) to fit in the space created from exfoliated C, D + E
357
What is Ackerman-Proffit Skeletal Class II?
Md retrusive relative to Mx
358
What are examples of types (transverse relationship) in Ackermann-Proffit?
``` Buccal Crossbite Palatal Crossbite Dental Skeletal Combined Dental and Skeletal ```
359
Why are early teens preferred as a window to start orthodontic treatment?
1. Easier to move teeth when mandible growing 2. Response to orthodontic forces is more rapid compared to adults 3. Appliances are better tolerated 4. Growth can be utilised to help sagittal or vertical change
360
What are issues with natal teeth?
1. May make breast feeding uncomfortable/painful | 2. Teeth are often sharp and can traumatise lip/tongue/soft tissue
361
What indications are there to start orthodontic treatment when there is established permanent dentition?
Most Malocclusion
362
What is the technique for Mandibular Superimposition?
Growth can be determined from the angle between the SN lines (anterior cranial base planes) where stable landmarks are used for orientation: 1. The anterior contour of the chin just above its maximum convexity 2. The outline of the inner cortex of the symphysis 3. The contours of the inferior dental canal 4. The lower outline of the crypt of the developing third molar (until the roots form).
363
According to Scammon's Growth Curve, which system displays most rapid growth early in life, then in teenage years?
General (Skeletal)
364
What is Facial Neotony / Paedomorphosis?
Retention of juvenile features as an adult: Larger eyes Small nose Full lips Round face
365
What are aspects of aesthetics in the horizontal plane?
- Broad evenness in height between the horizontal thirds | - Lips positioned in the top 1/3 of Lower 1/3
366
What does irregularity index measure?
Distance between two contact points. Higher distance equates to higher irregularity
367
What are the 6 steps in Moyer's Mixed Dentition Analysis?
1. Full M-D width of lower + upper incisors individually Then take sum all measurements 2. Measure the available mandibular + maxillary arch space per quadrant (Total = 1-2 + 2-6 per quadrant) 3. Predict the size of unerupted 3-5s on all quadrants using Moyer’s Table to calculate estimated space needed for permanent 3-5s based on arch incisal width (step 1) + confidence interval 4. Calculate the space excess/deficiency in each quadrant (Space = Quadrant Arch Length - Incisal width) 5. Consider the effect of FPM adjustment (depends on terminal plane relationship) 6. Compute the overall alignment potential
368
What happens if Chronological/Dental/Skeletal ages don't coincide?
1. Use Chronological Age for Overall Growth and Development 2. Use Dental Age for Dentoalveolar problems 3. Use Skeletal Age for Craniofacial Problems This will determine treatment approaches and timing
369
What trends occur in Inter-Molar width between 12-18 years?
Decrease minimally ~1mm (relatively stable)
370
What is the Functional matrix theory of craniofacial growth (Moss Theory) and what evidence supports it?
Growth occurs as a response to functional needs and is mediated by the soft tissues in which skeletal bones are embedded. Evidence: - Microcephaly result in small brains and small cranial vaults. - Large eyes result in large orbital cavities. - Shrinkage of alveolar ridge after tooth extraction
371
T/F: Females will generally experience tooth eruption earlier than males
True
372
What indications are there to start orthodontic treatment when there is early permanent dentition?
Impacted teeth - can be any teeth Crowding Hypodontia
373
T/F: You can have bimaxillary protrusion and still be in a class I skeletal relationship
True - as both the maxilla are prognathic in relation to the SNA + SNB angles, but ANB is still within the normal class I range
374
According to the cephalocaudal gradient which body part is most developed at birth?
The Cranium (60% developed)
375
What can influence buccal contours (negative space)?
Arch width + arch form Anterior-Posterior Maxillary Position Inclination of Posterior Teeth Inter-commissural distance during smiling
376
What is the smile arc?
Maxillary incisal edges and curvature of lower lip in a posed smile
377
In order to make a full assessment of a patient, what other information is needed other than arch form discrepancy?
Facial Pattern Soft Tissues Radiology and Cephalometrics Maturity Assessment
378
What can cause a central maxillary diastema?
1) Ugly Duckling phase - lateral displacement from erupting upper lateral incisor 2) Frenal Pulls
379
What is Class II Flush Terminal Plane relationship?
Flush relationship of Mx/Mn Es and where tips of both Cs are edge-to-edge
380
What is the significance of the apical base to orthodontics?
The apical base is the area where orthodontic tooth movement occurs
381
What are the pre-emergent tooth positions of successional pre-molars?
Should be contained by the all roots of the primary molars
382
How does the dental arch change between 6-12 years of age?
1. Inter-Canine Width - Mx: increase is largely through alveolar change, during eruption of the incisors and canines - Md: very little change → incisor irregularity 2. Dental Arch Length - Increases up to eruption of permanent incisors and first permanent molars is complete - Decreases once leeway space used by canines and premolars 3. Inter-Molar Width - Mx & Md: increase slightly (1-2mm)
383
Where is the Porion (Po)?
Soft tissue landmark - The upper margin of the ear canal
384
T/F: Both Mandibular inter-canine width and dental arch length both decrease due to late lower incisor crowding (tertiary crowding)
True
385
What should be the relationship be between the upper and lower lip and Rickett’s Esthetic Plane (E-Plane)?
In normal occlusion: 1. Lower lip will be closer to E-line than upper lip 2. At 12-14 years, lower lip to be -2 ± 3mm behind E Plane
386
What is Foster and Hamilton Class III Occlusion?
Distal surface of lower 2nd molar in anterior relationship to that of upper 2nd in centric occlusion
387
What direction does the nose grow?
Inferior + Anterior
388
T/F: Absolute growth of Lower + Upper Lips exceeds Lower LAFH
True
389
What permanent teeth do we expect to see at age 11?
Upper 3s | Upper and Lower 5s
390
What is the average space of leeway space in both arches?
``` Mx = 1.5mm/quadrant Md = 2.5mm/quadrant ```
391
What 5 factors can result in premature tooth eruption?
1. Genetic Factors 2. High Birth Weight 3. Early Puberty 4. Endocrine Abnormalities 5. Early loss of primary teeth through trauma, caries, perio
392
What are two methods of measuring dental age?
1. Eruption Count | 2. Nolla Calcification Staging
393
What are the 7 structural signs of mandibular growth rotations?
1. Inclination of Condylar Head 2. Curvature of Mandibular Canal 3. Shape of Lower Border of Mandible 4. Inclination of Mandibular Symphysis 5. Interincisal Angle 6. Interpremolar + Intermolar Angles 7. Anterior Lower Face Height (LFH)
394
What 5 factors aid ideal dental alignment?
1. Use of interdental, primate and leeway spaces 2. Increased inter-canine width, mainly due to transverse growth 3. Proclined eruption of permanent incisors, esp Mx, forming a wider arch and increases dental arch length 4. Appositional growth of alveolar processes in 3 planes (transverse, vertical, anterior-posterior 5. Appropriate size of apical base and teeth
395
What is a Mesoprosopic facial type?
Average face type when referring to extra-oral features
396
Which direction does the ramus grow?
Distally - there is significant remodelling of the ramus: - Resorption anteriorly to allow for more room in the arch for posterior permanent teeth - - Deposition posteriorly
397
What relationship should there be for good aesthetics in embrasures?
Embrasures should gradually increase in size the more distal you move
398
What is the growth mechanism of the naso-maxillary complex post natally?
Intramembranous Ossification
399
What is juvenile occlusal equilibrium?
The slowing rate of eruption once the erupted tooth approaches the occlusal plane. Teeth then erupt at a similar rate to the vertical growth of the ramus to maintain occlusal contact

BDS3 University of Adelaide Dentistry (28 decks)

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