Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Dentistry > Orthodontics > Flashcards

Orthodontics Flashcards

1
Q

OverJet

A

The horizontal distance from the labial surface of the lower incisors to the palatal surface of the upper incisors.

Normal is 2-4mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Overbite

A

The vertical distance from the incisal edges of the upper and lower central incisors.

Normal value: 2-4mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Crowding - classification of severity

A

Mild <4mm
Moderate 5-9mm
Severe >9mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Common developmentally absent teeth

A

Combined : 2% in caucasians

Lower Second Premolar
Upper Lateral Incisor
Upper second premolar
3 molars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Types of Supernumaries

A

Conical
Tuberculate
Supplemental
Odontome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Porion

A

Upper margin of boney external auditory meatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pogonion

A

Most anterior point of mandible/bony chin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Sella

A

Midpoint of the sella turcica i.e. the pituitary fossa (on lateral ceph)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Nasion

A

The intersection of the frontal bone and the nasal bones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Holdaway Line

A

A line drawn from the anterior soft tissue chin up through the upper and lower lips

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Rickett’s E plane

A

A line drawn through the soft tissue chin up through the tip of the nose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Menton

A

Most inferior point of the anterior mandible at the symphysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Gonion

A

The lowest point on the curvature of the angle of the mandible where the body of the mandible meets the ramus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

ANS

A

Anterior Nasal Spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

PNS

A

Posterior Nasal Spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A Point (sub-spinale)

A

Deepest point of the curvature of the anterior maxilla (between the ANS and the alveolar crest of the upper central incisor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

B Point (sub-mentale)

A

The deepest point on the curvature of the anterior mandible (between the pogonion and the alveolar crest of the lower central incisors)

18
Q

Maxillary Plane

A

A plane from the ANS to the PNS

19
Q

Mandibular Plane

A

Gonion to Menton

20
Q

Functional Occlusal Plane (FOP)

A

A line passing through the occlusion of the premolars (or Es) and the permanent molars

*Used in WITS analysis

21
Q

Frankfort Plane

A

A line drawn from the porion (most superior part of the boney EAM) to the orbitale (the most inferior portion of the orbital rim)

22
Q

ANB angle

A

The angle from point A to the Nasion to point B

Calculated by determining the difference between the SNA and the SNB

2-4 degrees = skeletal base I
>4 degrees = skeletal base II
<2 degrees = skeletal base III

23
Q

SNA/SNB compensation for sella or nasion abnormality

The Eastman Correction

A

First ensure the position of the sella is normal:
Measure angle SN to maxillary plane which should be 8deg +/- 3deg

SNA normal value is 81 degrees (caucasian)

For every degree > 81deg subtract 0.5deg from SNB

For every degree < 81deg add 0.5deg to SNB

24
Q

The Eastman Analysis

A

SNA and SNB
Determine ANB

Apply Eastman Correction

Draw mandibular plane (Go-Menton)
Draw maxillary plane (ANS to PNS)
Angle between them is MMPA
Measure the lower face height
Assess angulation of Incisors
Measure inter-incisal angle
25
Q

Maxillary-Mandibular Plane

A

27deg +/- 4

If this angle is significantly >32 deg then lower facial height is increased

If this angle is < 23 then the anterior lower facial height is reduced

26
Q

Lower face height percentage

A

Should be 55%

Lower third should be 33% or equal to midface

27
Q

Angulation of Incisors

A

Measured by drawing a line through the long axis of the tooth and the respective alveolar plane

Upper incisors = 109deg
Lower incisors = 93 deg

If the angles are reduced then the teeth and retroclined vs increased and they are proclined

N.B. The lower incisal angle is inversely proportional to the MMPA i.e. is 93 deg where the MMPA is 27deg

28
Q

Inter-incisal angle

A

Intersection of the long axes of the upper and lower incisors

= 133-135 deg

29
Q

SNA

A

Gives the AP position of the maxilla

Normal value is 81deg

30
Q

SNB

A

Gives the AP position of the mandible

Normal value is 78 deg

31
Q

African Variation in Eastman Analysis

A

SNA - 85
SNB - 80
ANB - 5
MMPA - 28

Upper incisal angle 118
Lower incisal angle 96

32
Q

Chinese variation in Eastman Analysis

A

SNA- 83
SNB- 80

ANB- 3
MMPA- 28

Upper incisal angle- 113
Lower incisal angle- 96

33
Q

Ballard’s Conversion Tracing

A

The Lines are drawn as for measuring incisal angles

The upper incisor is then tipped to it’s ideal 109deg about a point 1/3 from it’s root apex

The lower incisor angle and the MMPA need to equal 120deg

This new ideal position of the lower incisor is drawn and projected until it meets the upper incisor

This will represent the angles incisor classification and removes any dental compensation

34
Q

WITS analysis

A
  1. Uses the FOP
  2. A perpendicular line drawn from A point to the FOP
  3. A perpendicular line drawn from B point to the FOP
  4. Measure the difference between where these lines meet the FOP

Within 1mm = skeletal I
If A-FOP is >1mm ahead of B-FOP = skeletal II
If B-FOP is >1mm ahead of A-FOP = skeletal III

35
Q

Index of Orthodontic Treatment Need (IOTN)

A

To determine need for orthodontic treatment

2 elements:

Dental component (1-5)
Aesthetic component (1-10)
36
Q

IOTN dental component grading

A

Grade 2-5

Increased over jet (lip competence)

Grade 2-4

Reverse overjet (S&amp;M difficulties)
Overbite (ST trauma)
Crossbite 
Open bite 
Displacement 
Grade 4
Reverse overjet with S&amp;M difficulty
Lingual crossbite
Impacted partially erupted teeth
Uncomplicated Supernumerary teeth

Grade 4 and 5

Hypodontia

Grade 5

Impeded eruption of teeth
Submerged deciduous teeth
Cleft lip and palate

38
Q

IOTN grade 1

No treatment need

A

Extremely minor malocclusion including displacements of <1mm

39
Q

IOTN Grade 2

Minimal need for treatment

A

Increased overjet 3.5mm to 6mm with competent lips

Reverse Overjet 0-1mm

Anterior or posterior crossbite of <1mm

Anterior or posterior open bite 1-2mm

Increased overbite >3.5mm (no gingival contact)

Displacement of teeth 1-2mm

*uncomplicated pre or postnormal occlusions

40
Q

IOTN grade 3

Borderline need for treatment

A

Increased overjet 3.5mm to 6mm but with incompetent lips

Reverse overjet 1-3.5mm

Anterior or posterior crossbites 1-2mm

Lateral or anterior open bite 2-4mm

Increased and incomplete overbite without gingival trauma

Displacement of 2-4mm

41
Q

IOTN 4

Treatment required

A

Increased over jet >6mm
(but <9mm)

Reverse overjet 1-3.5mm (with S&M issues)
Reverse overjet >3.5mm (with no S&M issues)

Anterior or posterior crossbites >2mm

Lateral or anterior open bites >4mm
Posterior lingual cross bite (with no functional buccal contact)

Increased and complete overbite with ST trauma

Displacement of >4mm

Mild to mod hypodontia (less than one tooth in each quadrant)

Partially erupted teeth, tipped and impacted against other teeth

Existing supernumerary teeth

42
Q

Leeway space

A

Surplus space for the permanent successors (3,4 & 5) left by the discrepancy in width with the deciduous predecessors (c, d & e)

1-1.5mm in the maxilla
2-2.5 in the mandible

43
Q

IOTN 5

Treatment Required

A

Increased overjet >9mm

Reverse overjet >3.5mm
With speech or masticatory difficulties

Extensive hypodontia (>1 tooth missing per quadrant)

Impeded eruption of any teeth for any cause (except 3rd molars)

Submerged deciduous teeth

Cleft lip and palate

Dentistry (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions