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Ortho Exam 1 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Frankfort Plane

A
  • Horizontal Reference Line: Normal
  • Upper rim of external auditory meatus (Porion) –> Inferior border of orbital rim (Orbitale)
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2
Q

What are 2 problems with the Frankfort plane?

A
  1. Hard to locate porion on radiograph
    machine porion:
    * ear piece helps find porion.
    * Can be off from ideal anatomic porion
    SN Plane=Solution
    * alternative horizontal reference line
    * easily detected & reliable
  2. Frankfort plane is not always horizontal for ppl physiologically
    * ppl hold their heads at different angles (up to 10 degrees)
    * Physiological head position=NHP
    * NHP is preferred over anatomical horizontal plane (FP)
    * reproducible w/in 1-2 degrees (FP more reproducible)
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3
Q

SN Plane

A
  • Alternative horizontal reference line
  • Sella Turcica (S)–> Jxn b/w Nasal & Frontal Bones (N)
  • avg orientation: 6-7 degrees up & anterior to FP
  • Most commonly used bc done growing at 7 y.o.
  • Increases reliabilility and reproducibility
  • Decreases accuracy

Always note the inclination of SN to the true horizontal plane or FP if true HP is not known
* If SN differs from 6 degrees
* any. measurement based on SN should be correct by this amount

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4
Q

Steiner Analysis

A
  1. 1st modern cephalometric anylsis
    * Displayed measurements that emphasize individual measurements & interrelationship in a pattern
    * Guides for using cephalometric measurements in tx planning
  2. ANB Angle=SNA - SNB
    * Magnitude of skeletal Jaw discrepancy that must be overcome by compensations during tx
  3. Measured the angular & mm relationship of:
    upper incisor to NA Line
    * position of max teeth to maxilla
    Lower incisor & Chin to NB Line
    * position of lower incisors to mandible
    Established the relative protrusion of the dentition

Chin Prominence:
* mm distance from NB line to Pogonion

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5
Q

Holdaway Ratio

A

Ratio of the chin (pogonion) to mandibular incisors

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6
Q

Steiners Analysis: Criticism

A

ANB angle is influence by 2 factors other than AP differences in Jaw Position
1. Vertical Height of the Face
* Increased Vertical Distance from Nasion & Pts A/B= Decreased ANB angle

  1. Abnormal AP position of Nasion affects angle size
    * As SNA & SNB becomes larger & Jaws more protrusive= Larger ANB angle
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7
Q

ANB Angle

A

ANB angle=SNA - SNB
* magnitude of Skeletal Jaw discrepancy that must be overcome/compensated by tx

Gives AP Measurements: Class 1, 2, or 3 occlusion:
* Class 2 Skeletal Relationship: (+)
* Class 3 Skeletal Relationship: (-)

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8
Q

SNA & SNB Angles

A

relationship of maxilla & mandible to the cranial base
* Lower SNA(<90)= Maxillary Deficiency

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9
Q

Sassouni Analysis

A

1st to emphasize:
* Vertical and horizontal relationships
* interaction b/w vertical and horizontal relationships

Well proportioned face:
* Horizontal planes tend to converge toward a single point

Vertical Proportions of face=Inclination of horizontal planes to each other

Skeletal open bite vs Skeletal Deep BIte

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10
Q

Skeletal Open Bite vs Skeletal Deep Bite

A

Skeletal Open Bite:
* Aka Open Bite Malocclusion
* horizontal planes intersect close to the face & diverge quickly as they go anterior
* Facial Proportions are:
* Long Anterior
* Short Posterior

Skeletal Deep Bite:
* Aka anterior deep bite
* horizontal planes are nearly parallel & converge behind the face & diverge slowly as they go anterior

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11
Q

Harvolds Analysis

A

Severity or degre of Jaw disharmony
* Developed standard the “Unit Length” of maxilla & mandible

Maxillary Unit Length:
* posteior border of the mandibular condyle to Anterior Nasal Spine (3mm width)

Mandibular Unit Length
* Posterior border of mandibular condyle to anterior point of the chin (Gnathion)

Size Discrepancy b/w the Jaws= Maxillary Unit Length - Mandibular Unit Length
* Tooth position has no influence

Lower Face Height= Upper ANS (3mm thick) to Menton

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12
Q

Wits Analysis

A

Severity or degree of jaw discrepancy
* overcome the limitations of ANB
* influenced by teeth-horizontally & Vertically (opposite of Harvold)
* Use functional occlusal plane

Based on the projection of pts A & B to the occlusal plane
* measured the linear difference b/w points

Normal AP position of the Jaw:
* Pt A & B Projections will intersect the occlusal plane at nearly the same point
* Magnitude=A1-AB

Class 2 Discrepancy: (+)
* Pt A is in front of pt B
* Magnitude: how many mm b/w A & B

Class 3 Discrepancy: (-)
* Pt B is in front of pt A

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13
Q

Wits Analysis: Limitations

A
  1. Fails to distinguish Skeletal From dental Discrepancies
  2. Does NOT specify which jaw is at fault if there is a Skeletal Problem
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14
Q

McNamara Analysis

A

More precise Jaw & tooth positions
* combines elements of previous approaches (Ricketts & Harvold) + original measurements

Reference Lines:
* Anatomic Frankfort Plane
* Basion-Nasion Line

1st Step: Eval AP Position of the Maxilla & Mandible ro the Nasion Perpendicular
* Vertical line extending down from Nasion, perpendicular to the FP
* Maxilla= on or slightly ahead of perpendicular
* Mandible: Slightly behind

2nd Step: Compare Maxillary & Mandibular Lengths via Harvolds Apprach
* Maxillary Length
* Mandibular Length
* Lower Face Height

Measurements:
Maxillary Protrusion:
* nasion perpendicular to Pt A
* Mean: 2mm

Maxillary Incisor Protrusion:
* Line parallel to Nasion Perpendicular to Labial surface of incisor
* Mean: 4 mm

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15
Q

McNamara Anlysis: Strengths

A
  1. Relates the Jaws to each other via Nasion Perpendicular
    * Difference in AP positions of the Jaws to true vertical line
  2. Uses Normal Data based on Bolton Sample
    * Available in template form
    * highly compatible w/prelim analysis by comparison w/bolton templates
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16
Q

Angles Classification of Malocclusion applied to what 4 distinct characteristics?

A
  1. Classification of malocclusion
  2. Molar relationship
  3. Skeletal Jaw Relationship
  4. Growth Pattern
17
Q

How did the 5 Characteristic Classification System overcome Angle’s major weaknesses?

A

Overcame Angles major weaknesses by:
* eval of crowding & asymmetry w/in dental arches (included incisor protrusion)
* Info about skeletal Jaw Proportions at the appropriate time; relationships in each plane of space
* relationship b/w protrusion & crowding
* Transverse, vertical, & AP planes of space

18
Q

5 Characteristic Classification System:

Draw Ven Diagram

A

Ackerman & Proffit: 1960
5 major characteristics of Malocclusion:
1. Dentofacial Appearance
Frontal & Oblique Facial Proportions
Symmetry
Anterior Tooth Display
Orientation of the esthetic line of occlusion
Profile

  1. Alignment
    Crowding or spacing
    Arch Form
    Symmetry
    Orientation of the Functional LIne of occlusion
  2. AnteroPosterior
    Angle Classification: is it skeletal or dental?
  3. Transverse
    Crossbites: is it skeletal or dental?
  4. Vertical
    Bite Depth: is it skeletal or dental
19
Q

What were the 2 additions to the 5 characteristics classification system?

A
  1. Orientation of the esthetic line of the dentition
  2. Supplemnt the traditional 3D description of facial and dental relationships w/rotational characteristics around each plane of space (Roll, Pitch, Yaw)
20
Q

Esthetic Line of the Dentition

A

Follows the facial edges of the maxillary anterior & posterior teeth
* along incisal edges & cusp tips
* Transverse orientation

Incorporate tooth-lip relationships into diagnostic eval of tooth positions

21
Q

Pitch

A

(AP); Y axis
1. Excessive Upward Or downward rotation of the dentition to lips/cheeks
2. Vertical relationship of the teeth to the lips & cheeks
* Downward or upward translation w/no pitch deviation; rare-during growth or treatment
* Pitch upward or downward anteriorly
* Pitch upward or downward posteriorly

  1. Pitch of the dentition to facial soft tissues evaluated during clinical exam

Compare:
* esthetic line of dentition
* ntercommisure line

Downward pitch of anterior teeth
* anterior deep bite

22
Q

Yaw

A

(Transverse): Z axis
Characterize Transverse asymmetries
1. Rotation of the Jaw or Dentition to one side or the other

Yaw of the:
* Dentition relative to the jaw
* mandible/maxilla that takes the dentition w/it

Causes:
* Skeletal or Dental midline deviations
* Unilateral class 2 or 3 molar relationships

Extreme Yaw Causes:
* asymmetric Posterior crossbite

23
Q

Roll

A

(Vertical): X-axis
Up or Down Roation on one side or the other
* The vertical Position of the teeth when its different on R & L Sides

Compare the esthetic line to:
1. Facial Soft Tissues
* Reference: Intercommisure Line
* cant see on dental casts or photograph w/fox plane
* See in frontal or oblique views where Lips are relaxed or on smile (Clearer
2. Facial Skeleton
* reference: interoccular line
* Fox plane–>** occlusal plane cant**

24
Q

Posterior Crossbite

A

Described in terms of upper molar position
* specifies which teeth (max or mandibular) are displaced from normal position

Due to Skeletal or Dental components:
* Dental: Adequate palatal width, narrow dental arch
* Skeletal: inadequate palatal width

Width of Maxillary skeletal base=width of palatal vault on casts
1. Dental Problem:
* IF wide palatal vault width–> Dentoalveolar processes lean inward
* caused by arch distortion
2. Skeletal Problem
* If Narrow palatal vault width–> maxillary teeth lean outward
* caused by narrow maxilla width

Teeth can compensate for transverse problems:
* Tip facially or lingually if the skeletal base is narrow or wide

25
Q

Long Face syndrome

A

skeletal open bite (High Mandibular-Palatal Plane ANgle)
* anterior bite malocculsion:
* excessive eruption of posterior teeth
* downward rotaiton of mandible/maxilla
* Normal (or even excessive) eruption of anterior teeth
* HOrizontal planes intersect near face & Diverge quickly-anterior
* Long Anterior Face
* Short Posteiror FACE

26
Q

Short Face Syndrome

A

Skeletal Deep Bite (Low Mandibular-Palatal Plane angle
* Anterior Deep Bite
* normal eruption of incisor teeth (anterior)
* Roation of both jaws in the opposite direction
* insufficient eruption of posteiro teeth
Horizontal planes are nearly parallel
* converge before the face
* Diverge slowly-anterior

27
Q

Mandibular-palatal angle

A

palatal & mandibular plane angle
* Low=Skeletal Deep Bite
* High=Skeletal open bite

28
Q

Counterpart Analysis

A

Emphasized that changes in proportions in one part of the head/face can either:
* Increase jaw discrepancy
* compensate so the jaw fits correctly

If Long Anterior Face height: Facial balance and proportions are preserved if:
* Large Posterior Face Height & Mandibular ramus height

Short posterior face height can lead to Skeletal open bite
* even if Anterior Face height=Normal
* Disturbed proportions

Long cranial base:
* Normal Maxillary & Mandibular lengths

29
Q

If Long Anterior Face height, How would facial balance and proportions be preserved?

A

Long Anterior Face Height
* Large Posterior Face Height
* Large Mandibular Ramus Height

IF SHORT POSTERIOR FACE HEIGHT=Skeletal Open bite
-even if NOrmal Anterior Face height

30
Q

If the Cranial Base is long, and Maxillary and mandibular lengths are normal: Compensatory vs Not

A

No Compensation:
Maxilla will be moved forward relative to the mandible
* Result: maxillary protrusion

Compensation:
Short maxilla

31
Q

What relationships does cephalometric analysis aid us in clearly evaluating?

A

Underlying cause of malocclusion

Look at
* individual measurements compared to the norm
* pattern of relationships (Soft tissue relationships)

32
Q

What is the major goal of cephalometric analysis?

A
  • Establish the relationship of the structural components of the face in both the AP and vertical plane of space
33
Q

What are the steps in cephalometric analysis?

A

1 Draw Sassouni horizontal planes & examine their interrelationships
* are vertical planes proportional
* SN-MP Angle

2 Observe AP relationships with SNA and SNB angles
* McNamara Analysis
* Class I, II, III occlusion

3 Move True vertical lines to A & B to ID Protrusion (<4mm) or retrusion

4 Use Counter part analysis to verify measurements
* Face height
* Maxilla & Mandibular Unit Lengths

34
Q

Template Analysis:

A
35
Q

Arch Form

A

HOw the teeth:
* sit in the arch
* Relationship to the arch

Can have:
* crowding + malalignment= Normal Jaw position via cephalometric analysis
* perfect arch form–> Bad relationship to opposing arch due to skeletal defect (underdeveloped maxilla)

36
Q

Dental midline deviations can be due to:

A
  • reflection of displaced incisors bc of crowding
  • Yaw discrepancy-whole dental arch is rotated to one side

Ortho Exam 1 (10 decks)

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