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requirements for normal occlusion

No open bite
minimal overjet
minimal overbite
normal tooth size
max intercuspation w/o shift

Dr. Andrews 6 keys to normal occlusion

Molar Key
crown angulation = mesiodistal tip
crown inclination
no rotations
no spaces and all teeth in contact
occlusal plane = flat to slight spee

___ is the distal surface of the distobuccal cusp of the maxillary 1st molar should be in contact with the mesial surface of the mesiobuccal cusp of the mandibular 2nd molar

Molar Key

The 2nd key to normal occlusion is the ___ which is a ___ and when the ___ is more distal than incisal

crown angulation
mesial tip of long axis/crown
gingival portion of long axis of clincal crown

____ determines the mesio-distal space occupied

crown angulation

crown inclination for:
- upper and lower anteriors
upper posteriors
lower posteriors

- labial crown inclination
- Lingual
-Lingual (progressively inclined as move back)

T/F Roated teeth take up more space than non rotated teeth


Flat occlusal plane permits ____

max intercuspation

____ is the father of modern ortho, credited with much of occlusal concept

Edward H. Angle

Angles 2 postulates

Upper 1st molar = key to occlusion
MB cusp of upper molar should occlude in buccal groove of lower molar

____ is a smooth curve passing through central fossa and over cingula of max teeth and buccal cusps/incisal edges of mandibular teeth

Line of Occlusion

Normal molar relationship
line of occlusion is incorrect due to malposed/rotated teeth

Class I Malocclusion

Lower molar = distally positioned relative to upper (overbite)
Line of Occlusion NOT specified =

Class II Malocclusion

Protruding Upper Incisors

Class II Division I

Retrusive Upper Incisors

Class II Division II

Lower molar is mesially positioned relative to upper molar (UNderbite)
Line of occlusion not specified =

Class III

Class II jaw relationship

mandible distal =retronagthic
usually with class II moalr relationship

Class II growth pattern

Down and Back growth of mandible

Class III jaw relationship

Mandible mesial = pronagthic

Class III growth pattern

forward growth of mandible

Profitt and Ackerman's 5 major characteristics

1. facial proportions and aesthetics
2. alignment and symmetry w/in distal arches
Skeletal and dental relationship:
3. Transverse plane
4. anterioposterior plane
5. Verticle plane

convex facial profile=

class II jaw

Concave facial profile =

class III

_____ = anterior or posterior inclination of the lower face relative to forhead - does not indicate facial/dental disproportions


Intra-Arch alignment and symmetry takes into account ____

crowding, spacing, symmetry

transverse deviation includes ___ where max posteriors are lingually postioned relative to mandibular teeth

posterior crossbite

___ =upper molars are lingual to normal

bilateral max lingual x-bite

____ is when lower molars are buccally postioned on 1 side

unilateral mandibular buccal x-bite

___ is due to displacement of teeth from normal positoned adequate palatal width

Dental Crossbite

_____ is due to inadequate palatal width

skeletal x-bite

Overjet =

horizontal overlap of incisors (should ideally be 2-3mm)

US population have 35% with normal occlusion and 65% w/ malocclusion - ___ with an Unknown cause

5% (so majority of malocclusion the cause is known)

Etiologic factors of malocclusion include

specific causes, genetics, environment

_____ = chemical agents producing embryo defects


IntraUterine molding, trauma to mandible and jaw fractures are ____

skeletal growth disturbances

____ can affect Jaw growth

muscle dysfunction

Musculature usually pulls jaw ____

down and forward

_____ caused by excessive growth hormone release by ______ pituitary tumor which results in excessive ____ growth


Unknown cause, unilateral excessive mandibular growth, common in females 15-20 yrs old

Hemimandibular Hypertrophy

Sclerotic bone, heavy fibrous gingiva, CC (Cleidocranial Dysplasia) and ankylosed premolar are all characteristics of

eruption interference

____ is multiple supernumerary teeth which lead to mechanical interference of normal tooth eruption

CCD = Cleidocranial Dysplasia

early loss of primary teeth leads to ___


*** 2 ways genetics can lead to malocclusion inheritance

1. disproportion between size of teeth and size of jaw = crowding or spacing
2. disproportion between upper and lower jaws = improper occlusal relationshps

T/F primitive man had better occlusion

True - if they didn't they were natural selected out of population cause they couldn't eat correctly

____% of dental/Facial variation can be attributed to heredity factors


Heritability of skeleton = __
Heritability of dentition = ____
because environment leads to ____

dental variation

What is the strongest genetic influence

mandibular prognathism = hapsburg jaw

2 theories of environmental influence

Equilibrium = pressure from cheeks, jaw
Functional influence = form/function

____ would be a equilibrium effect on dentition

tongue pressing against and moving teeth after a stroke

____ is a functional influence on dentofacial development


narrow+ steep maxillar, anterior open bite, tongue lowers and pressure on upper molars, cheek pressure contricts upper arch are results of =


altered respiration (i.e. breathing through outh) can result in

adenoid facies

what are the 2 purposes of ortho records

treatment start point
additon of info from clinical exam

3 major categories of ortho records

health of teeth and structure
allignment and occlusal relations
facial and jaw proportions

standard ortho records (Steps)

exam w/ photo, radio, cephalo
study casts
collection of diagnostic database

class II skeletal jaws are possible candidates for

head gear for skeletal modification

___ determines vertebral maturation and predicts remaining growth

cephalometric radiograph and hand wrist

____ around crowded incisors possibly leads to dehiscence of tissue when tooth is aligned

inadequate attached gingiva

Smile analysis includes

Social smile and emotional smile

full smile wants ___% incisal display


____= distance btw max posterior teeth and inside of cheek (ideally minimal as possible)

buccal corridor

smile arc is contour of upper anterior incials in relations to ____, the goal is ___

curve of lower lip during social smile
match contour of lower lip

All the following are ____:
tooth proportions
golden proportion
height/width of max centrals
width of tooth should be 80% height
gingival height/shape/contour
connectors and embrasure (black triangles)


For lateral cephalometric x-rays you evaluate

dentofacial proportions and clarify the anatomic basis for a malocclusion

Study casts allow eval of

arch length
Bolton = tooth size discrepancies
Bite registration

____ = don't want to move teeth around because prone to perio problems


Facemask therapy is used with ____

Class III underbite = pulls UPPER jaw forward

E line =

Nose to Chin

analysis of width of teeth and add them up to compare upper to lower jaw

Bolton Analysis

____ is the space mesial to canine in the max and distal to the canine in the mand

Primate space

____ is the difference between space needed and available for incisors

incisor liability

where does extra space for incisors come from

dental arch increase in width
labial positioning of the central permanant incisors
canines move back in mandibuar arch

Permanant canines and premolars are smaller than primary and result in ____

Leeway space

___ is used for correction of crowding and molar drift

leeway space

mesial migration closes space by ____

holding molars back (lower lingual holding arch)

to measure space available

measure arch perimter from 1st molar to other 1st molar
over contact points of posterior teeth and mesial edges

ehat are the 2 ways to measure

divide dental arches into straight line segments
or contour a peice of wire for measurment all at once

Amount of space required measured by ___(3)

mesiodistal of each tooth
contact pts to contact pt
sum width of individual

3 assumptions of space analysis

1. Anterioposterior position of incisor is correct
2, space available does not change due to growth
3. teeth present and normal sized

An arch length analysis for mixed dentition estimates if there is enough space for ____

permanant canines and premolars if molars are held in current position
only done in lower arch

mixed analysis helps determine

extraction cases
post treatment incisal stability
only in lower arch

3 most common analyses

estimation from porportional table
Johnston-Tanaka and Hixon-Oldfather

Use ____ when trying to discriminate between cases with just enough space for canines and premolars, and severely crowded cases

Mixed dentition analysis

Direct measurment by radiograph uses

must compensate for picture enlargment

analysis with little predictive value but can assess crowding

direct measurment

lower canines and premolars need at least

23 mm spacing

____ uses average of erupted teeth, no x-ray, measures SA (MD of 4 lower incisors and CDE space of each side) and SR (width of 4 lower incisors + 21 (= width of 3+4+5)


____ is combo of radiographs and predicitive table, SA-SR (Direct measure of 4, 5 from periapical and incisors from cast), predicts unerupted canines and uses predictive graph = best predictive method


analysis good for a combo of all ethnicities

direct measure of radiograph

If SA=SR what must be preserved

Leeway space to prevent mesial migration

If SA<SR by 1-4 mm (crowding) then

space regaining mechanics
i.e. headgear, expansion and lip bumper

If SA<SR by 5+mm (crowded)

tooth mass reduction by interprox rediuction or extraction

_____ = borrow leeway space, remove lingual sheath, place contact area @ incisal 1/3, adjust at 6 months

Lower Lingual Arch preservation

T/F Arch length analysis can be done with mixed dentition


___% of US population have size difference in teeth


Most common tooth size discrepancy =

Lateral max incisors (Peg)

tooth size analysis from permanant dentition =

Bolton Analysis

less than ____ tooth size discrepancy is rarely significant


Standardized radiographic head film with reference landmarks to make measurements


Cephalometrics are used to diagnose and treat by evaluating ____

dentofacial proportions and clarify anatomic basis for malocclusion i.e. how the major components of the face realte

cephalometrics are used in ortho to

diagnose and treat
growth eval
treatment eval
treatment prediction

x-ray to patient midsaggital place distance

5 ft

pt midsaggital place to cassette

15 cm

Any malocclusion is result of ____ between ___ and ____ which is affected by jaw relationshp

jaw position
position of teeth

cephalometrics can

distinguish between skeletal and dental contribution to malocclusion

_____ is produced by:
protrusion of max teeth
mandibular dificiency
downward/ backward rotation of mandible from excessive verticle growth of maxilla

Class II Division I malocclusion

Most important clinical use of cephalometrics

evaluation of ortho treatment
i.e. growth and treatment

3 major cephalometric superimpositions

SI on anterior CB along SN line
SI on maxilla
SI on mandible

what is the objective of cephalometric analyssi

visualize skeletal and dental contributions to malocclusion

13 major cephalometric landmarks

sella (S)
nasion (N)
basion (B)
Articular (Ar)
Porion (P)
Orbitale (Or)
Anterior Nasal Spine (ANS)
Posterior Nasal Spine (PNS)
Point A
Point B
Pogonion (POG)
Menton (Me)
Gonion (Go)

lowest point of anterior margin of foramen magnum


Intersection point between shadow of zygomatic arch and posterior arch of manibular ramus

Articular (Ar)

Midpoint of upper contour of Ext Auditory Canal

Porion (P)

Inferior part of orbital


Inner most point on contour of premaxilla between anterior nasal spine and upper incisor

Point A

Innermost point on contour of mandible between incisor tooth and chin

Point B

most anterior point or contour of chin


most inferior point on mandibular symphysis


midpoint of contour connecting Ramus and body of mandible


Cephalometric reference planes

anterior cranial base - sella - nasion
facial (nasion-pognion)
E plane = nose tip to pogonion

SNA = AP of maxilla and cranial base
>82 degrees =
< 82 degrees

maxilla forward
maxilla back/recessed

SNB = AP position of mandible to cranial base
>80 =
<80 =

prognathic mandible (protrusive)
retrusive = retronagthic


differences between SNA and SNB

>2 ANB =
<2 =

Class II = overbite (retronathic mandible)
class III = mandible ahead of maxilla = pronathic mandible

High steep mandibular plae angle =


low mandibular plane angle



Incisor Mandibular Plane Angle
mandibular plane and long axis of lower incisor
larger than 90 degrees = proclination of lower incisor

Analysis where a well proportioned face has horizontal planes converging at 1 point

Sassouni Analysis

Treatment Goals with cephalometrics

ideal OJ/OB, coincident midlines, class I molars and canines, coordiate arches and facial aesthetics

Surgical options =

maxilla + genioplasty
maxilla and mandibular (+genioplasty)
mandible oinly ( genioplasty)

Analysis which includes:
REF planes, NA perpendicular, Harvold analysis, mandibular position, U1 = point A perpendicular, L1 = A-Pog (rickets)

McNamara's Analysis

Analysis of Max and Mand lengths


Tangent side (away from movement) stimulates=
side that tooth is moving towards stimulates ___


5 mechasnical concepts in Ortho

center of resistance
center of rotation
Moment (want this to be minimal)

_____ occurs when force applied to center of mass

bodily movement = good

____ = point of concentrated resistance to movement

Center of Resistance CR

for a tooth, the CR is located

embedded portion - root

Normal location of CR =

1/3-1/4 between alveolar bone and apex of root
multirooted teeth = furcation

Force appled x distance (F x D)

Moment M

if there is further distance the moment will be ____, thus you must decrease ____ so dooth does not tip

force applied

you can cancel the moment by ___, thus producing bodily movement

coupling C

_____ is 2 forces aplied in equal magnitude, opposite direction, which produces PURE rotation around the CR


how is horizontal movement achieved

by cancelling out the moment by coupling

How do we apply coupling IN the bracket

engage the wire which has shape memory, if bent the wire will go back. The wire will try to straighten and will apply force, producing rotation through coupling

engaging a wire in an angulation bracket thus resulting in angulation is ___

2nd order coupling

engaging a rectangular wire in a bracket slot resulting in inclination is ___

3rd order coupling = torque

The simplest way to determine tooth movement is the ratio between

moment produced by applying force to the crown of tooth Mf and counterbalancing moment generated by bracket coupling

What is the simplest ortho momemnt

uncontrolled tipping

___ is motion of object that has force applied at a distance from CR, and counterbalancing couple to regulate roation

controlled tipping

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