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Flashcards in Orthodontics Deck (105):

primary teeth molar relationships
1. flush terminal plane
2. mesial step
3. distal step
4. Angle's Class III

1. normal relationship of primary molars, the primary 2nd molars determines the AP position of the permanent 1st molars
2. equiv to Angle Class I
3. equiv to Angle Class II
4. almost NEVER seen cause of normal pattern of craniofacial growth where mandible lags behind maxilla


most common initial relationship of primary molars is

edge to edge, flush terminal plane -> Class I


when erupting, permanent teeth move __ and _-

occlusally and buccaly


arch lengths

max - 128
mand - 126

for permanent teeth


incidence of malocclusion in a homogenous or heterogenous population is higher?

higher in HETEROgenous


skeletal open bite (long face syndrome)

assoc. with mouth breathing
-condition is not self correcting and worsens with time


malocclusions more identifiable in kids ages __ to __

7-9 cause eruption of permanent incisors reveal arch length discrepancies


Steiner analysis
1. SNA angle
2. SNB angle
3. ANB angle

1. SNA - sella turcica to nasion, shows maxilla and cranial base.
> 82 = mx prognathic
< 82 = mx retrognathic

2. SNB - SN and NB
> 80 = md prognathic
< 80 = md retrognathic

3. ANB - difference btw SNA and SNB
> 4 = Class II skeletal
< 0 = Class III skeletal


Angle Class I (A)

MB cusp of mx first molar lines up with buccal groove of md first molar; max centrals overlap md centrals
-most COMMON (70%)
-most common cause is discrepancy btw tooth structure and amt of supporting bone length
-most prevalent characteristic is CROWDING from not enough arch length


when crowding is > __ mm in the mandible, ext are often required

4 mm


In Angle Class II, there are 2 divisions

big diff btw division I and II is in division II, mas laterals are tipped

labially and mesially


Class II, Division I

Class II, Division II

I - max central and laterals are in extreme labioversion (protruded) DEEP BITE

II - body of mandible and its dental arch are in a distal relationship to the maxilla, while molar & canine occlusion are same as Class II, D I.


Sunday bite

forward postural position of mandible adopted by ppl with Class II


Class II (B) canine relation

Class III (C) canine relation

B: mandibular canine's distal surface is distal to max canine's mesial surface. max canine is mesial to mand canine

C: mand canine's distal surface is mesial to max canine's mesial surface. max canine is distal to mand. canine


when distocclusion occurs on only one side of the arch, it's called a __ of its division


ex. Class II, Division I Subdivision


ectopic eruption

tooth erupts in wrong place
-most common in max 1st molars and mand incisors, more common in maxilla, assoc. with Class II
-in 2-6% of population
-ectopic of max 1st molar - brass wire
-ectopic of mand laterals can cause transposition of lateral incisor and canine


pseudo-class III

mandibular incisors forward of max incisors in centric, but pt can bring mandible back without strain

-FORWARD SHIFT of mandible during closure to avoid incisor interference
-tx by eliminating CO-CR discrepancy


bimaxillary dentoalveolar protrustion

when teeth protrude in both jaws - lip strain


crossbites are assoc. with

jaw size discrepancy, hereditary (genetics), reverse over-jet, scissor bite NOT tongue thrusting

1. anatomical - smooth closure into centri
2. functional - caused by thumb sucking


when should ortho tx start to correct xbite


max expansion is the first step with PALATAL EXPANDER


scissor bite (bilateral lingual xbite)

from narrow mandible or wide maxilla


anterior xbite in primary dention indicates

skeletal growth problem and developing Class III malocclusion
-NOT self correcting so tx in mixed dentition
-most often assoc. with prolonged retention of primary tooth
-if tx is delayed, can lead to loss of arch length and you need M-D space


symptoms of digit sucking habit

anterior xbite, xbite, proclination of mx incisors, constriction of mx arch, retroclination of md incisors, class II


open bite

some teeth can't be brought into contact with opposing
-NOT cuased by tongue thrusting
-tongue thrust SWALLOW is the result of displaced incisors, not a cause


most common sequelae of digit sucking is

anterior open bite
-usually asymmetrical
-more common in african americans (but deep bites are more common in caucasians)


which grows first, max or mandible?

maxilla, the mandible LAGS


posterior xbite can be corrected how

palatal expansion to expand nasal floor (will create diastema)
-this is a problem in the TRANSVERSE plane of space
-correct posterior xbites and mild anterior xbites FIRST (severe anterior xbite usually second stage)


most common active tooth movement in the primary dentition is to correct

a posterior xbite (transverse plane prob)


maxillary mandibular plane angle (MMPA)

Mandibular plane Go-Me line and
Maxillary plane ANS-PNS line

the greater MMPA, the longer the anterior facial height

long face -> Class II
short face -> Class III


mandibular plane angle

steep correlates with short or long anterior facial vertical dimension?

STEEP - long face - anterior open bite - Class II

FLAT - short face - anterior deep bite - Class III


poor man's cephalometric

facial profile analysis
-AP position of jaws
-lip posture
-vertical face proportions
-inclination of mand plane angle

within lower 1/3 of face, mouth should be 1/3 of the way btw the nose and chin


most stable area to evaluate craniofacial growth is the __ cause of its early cessation to growth

anterior cranial base


frankfort-horizontal plane

connects PORION and ORBITALE

represents natural orientation of the skull


to predict time of pubertal growth spurt, get the most valuable info from a

wrist-hand xray
-ulnar sesamoid or hamate bones are landmarks


supervising a child's development of occlusion is most critical from ages __ to __

7-10 (mixed dentition)


performing a mixed dentition analysis

1. measure MD diameter of mand incisors and add
2. measure space avail for mand incisors
3. subtract, a NEG. means CROWDING

4. measure space avail for canine and premolars on each side of arch
5. calculate from table the size of canines
6. subtract, a NEG. means CROWDING


for the max arch, what teeth are used to predict the size of max canines and premolars?

mandibular incisors


Moyer's mixed dentition analysis

size of unerupted canines and PMs is predicted from knowing size (MD width) of mand incisors

never use max incisors (too much variation)


primate spaces are where in the:
max arch
mand arch

max arch - btw laterals and canines
mand arch - btw canines and 1st molars


relative to the primary mand. canines, the permanent mand. canines erupt in a __ direction

FACIAL, or are often right in line with the primary canines


in both arches, the permanent incisor tooth buds lie where in relation to the primary incisors?



leeway space is

diff. in total M-D width btw primary canine, first molar, second molar, permanent canine, first PM, second PM

permanent successors are usually SMALLER

mandibular = 3-4 mm
maxillary = 2-2.5 mm


late mesial shift of permanent first molar

during canine-premolar transition peirod, permanent 1st molars grow MESIALLY into leeway space after the primary 2nd molars are lost
-causes a loss in arch length


serial extraction

removal of select primary and perm. teeth in predetermined sequence. indicated in severe class I malocclusion in mixed dentition.

1. primary canines
2. primary 1st molars
3. permanent 1st premolars

interval btw ext is 6-15 mo.
-use lingual arch in mandible and hawley in maxilla


severe arch space deficiency in the permanent dentitition is > __ mm

10 mm, requires EXT


key to success in serial ext is to extract the 1st premolars before __ erupt

permanent canines!

usually concern is with permanent mand. canines and 1st PMs

in maxilla, after serial ext, the max canine will erupt down and back


most common impacted anterior teeth



3 principals when tx planning an impacted tooth

1. prognosis based on displacement and surgical trauma req for exposure
2. flaps should be reflected so tooth is pulled through KERATINIZED tissue (NOT alveolar mucosa)
3. adequate space should be in arch BEFORE you pull it out


assoc. of impacted canines with

missing laterals or short roots of laterals


what guides the eruption of canines?

distal aspect of the lateral roots


Supernumerary teeth

-more common in maxilla in midline
-2:1 males more common
-assoc. conditions: Gardner's, Down's, Cleidocranial Dysplasia, Sturge-Weber syndrome



more common in females


generalized causes of failed or delayed eruption are assoc. with

localized causes of failed or delayed eruption are

-hereditary gingival fibromatosis
-down's syndrome

-congenital absence
-abnormal position of crypt
-lack of arch space
-supernumerary teeth
-dilacerated roots


hyperparathyroidism causes what

premature exfoliation


maxillary diastema

98% 6 yr olds
49% 11 yr olds
-caused by tooth-size discrep, mesiodens, abnormal frenum attachment, or normal
-2 mm or less will close by itself
-if it's cause of frenum -> frenectomy when permanent canines erupt


methods to close a diasetma

-lingual arch with finger springs
-hawley with finger springs
-cemented ortho bands


6 types of ortho movements
1. tipping
2. translation
3. extrusion
4. intrusion
5. torque
6. rotation

1. tipping - rotation/pivot around axis of rotation (apical 1/3 of root)
2. translation - coupled force, difficult
3. extrusion
4. intrusion - difficult
5. torque - controlled root movement when crown is held stable, "uprighting"
6. rotation - recurring rotation after ortho tx is from persistence of elastic supracrestal gingival fibers


what kind of fibers are assoc. with relapse after ortho rotation

supracrestal gingival fibers (free gingival and transseptal)


an appropriate candidate for post-ortho circumferential supracrestal fibrotomy is what tooth

a rotated max. lateral
-incise all collagen fibers inserted into the tooth, eliminates relapse potential


rationale for retention is to

allow reorganization of gingival and periodontal tissues


for an appliance to be effective in translating tooth roots, it must be capable of

exerting a torque


fixed ortho appliances offer controlled movement in all 3 planes of space. 4 basic components are:

bands, brackets, archwires, auxillaries

Alloys used for archwires are
1) SS - can be controlled widely by cold work
2) chromium-cobalt - can be supplied softer, and heat increases strength
3) titanium - good combo of strength, springiness, good formability


properties of an ideal wire for ortho should possess

high strength, high range, high formability, low stiffness

-loops and helices are incorporated to increase the activation range


quad helix

FIXED appliance
-consists of 4 helices (2 ant, 2 post) for POSTERIOR CROSSBITE cases from thumb sucking


unbuffered phosphoric acid 35-50%

etching agent for bonding of brackets, tooth looks frosted

DO NOT use topical fluoride before etching cause fluoride decreases enamel solubility


indications for bands instead of bonded brackets

better anchorage for movement, for teeth that need lingual and labial attachment, short clinical crowns, surfaces incompatible with bonding


band cementation with

GI cements due to F- release, use cold slab technique


indirect method of bonding brackets > direct method

pros and cons?

pros - less time, accurate placement, controlled resin thickness btw tooth and bracket, easy clean up

cons - more technique sensitive

used in situations where visibility is a problem ex. lingual appliances


most widely used appliance by orthodontists is the

-tx comprehensive malocclusions of adolescent permanent dentition

-Siamese twin bracket (max anterior teeth)
-Broussard buccal tube
-Straight wire bracket and bracket with a 0.0222 x 0.028 rectangular slot
-Wire is usually 0.125 x 0.028


takes how long to upright a molar

6-12 months

use a EDGEWISE appliance

stabilization should last until lamina dura and PDL reorganize ~ 2 mo. for simple upright, up to 6 for grafts


one of the most significant complications of molar uprighting is

high mandibular plane angle -> can cause open bite, loss of anteiror guidance


whip-spring appliances are used to

DE-rotate one or two teeth


Space maintainers that replace ONE prematurely missing primary tooth
1. Band and Loop
2. Distal Shoe

1. B& L - for primary 1st molar
2. Distal shoe - for primary 2nd molar loss before the permanent 1st molar erupts (kids under 5 or 6)


Space maintainers that replace MULTIPLE prematurely missing primary tooth
1. Lingual arch
2. Nance
3. Partial denture

1. Lingual arch - primary 2nd molars or permanent 1st molars are banded, when permanent incisors have erupted
2. Nance - bilateral loss of primary max. molars, prevents mesial rotation and drifting of permanent max. molars
3. Partial - bilateral posterior space maintenance when incisors haven't erupted, also for missing anteriors when esthetics an issue


Removable ortho appliances are generally restricted to what movement


1. Active removable - head gears, lip bumpers, vacuum formed
2. Passive - bite planes, occlusal splints, retainers


indications of removable appliances

1. retention after tx
2. limited tipping
3. growth modification during mixed dentition


most common removable retainer in ortho is the

Hawley retainer
-clasps on molars and outer bow with adjustment loops canine to canine
-palatal coverage make it possible to incorporate a BITE PLATE lingual to mx incisors to control bite depth (good for ppl with overbite)


Begg appliance

round wires that fit loosely into bracket's vertical slot


Frankel's appliance

removable app used for abnormal (hyperactive) soft tissue patterns


Headgear used to maintain

extra-oral anchorage and traction
-advantage is it PERMITS POSTERIOR MOVEMENT of teeth in one arch without disturbing the other arch


4 basic headgears

1. cervical pull
2. straight pull
3. high pull
4. reverse pull


Cervical pull headgear

-for distal and downward force against maxillary teeth and maxilla
-con = extrusion of max molars
-indications = Class II, Div I


Straight pull headgear

-like cervical but places a force in a straight distal direction from max molar
-indications = Class II, Div I


High pull headgear

-distal and upward force on max teeth and maxilla
-indications = Class II, Div II with open bite


Reverse pull headgear

EXTRAORAL component
-indications = Class III where protraction of maxilla is desirable


finger springs is the best method to

tip max and mandibular anterior teeth

Z-springs can also be used but delivery heavy forces


maxillary incisor rotation is best treated when

after all permanent teeth have erupted with simple removable appliances


Tissue borne functional appliances include (1)

-expands arch by padding against the pressure of lips and cheeks on teeth, postures the mandible forward and downward


Tooth borne functional appliances include (4)

1. activator - advances mandible to edge to edge to induce mandibular growth and correct Class II

2. Bionator - similar to activator

3. Herbst - fixed or partially removable, posture the mandible forward and induce growth

4. Clark's twin block - postures mandible forward with help of occlusally inclined guiding planes and bite blocks


first order bend in a wire is in which plane



cartilage growth occurs 2 ways
1. appositional
2. interstitial

1. appositional - recruitment of fresh cells, chondroblasts, add new matrix
2. interstitial - mitotic division and deposit of more matrix around chondrocytes already in the cartilage, HYALINE CARTILAGE grows this way


sites of interstitial growth incl.

mandibular condyle, nasal septum, spheno-occipital synchondrosis


bone forms by either endochondral or intramembranous ossification

-begins in embryo where mesenchymal cells differentiate into fibrous membrane or cartilage
-grows by APPOSITION

1. intramembranous - in membranes of osteoprogenitor cells. MAXILLA and MANDIBLE, flat bones of skull and part of clavicle form this way

2. endochondral - remainder of skeleton, in hyaline cartilage model, for short and long bones


bone growth only occurs by __ growth



major site of growth of the mandible is the

-resorption along anterior ramus creates space for mand. molars
-main growth thrust is UP and BACK causing the body fo the mandible to move DOWN and FORWARD


growth at the mandibular condyle during puberty results in

increase in posterior facial height


bone deposition in the __ region is responsible for lengthening of the maxillary arch

max tuberosity
-max arch elongates, moves posterior, and increases in height


alveolar bone only exists to

support teeth
-in a kid, the alveolar process grows in height and length to accomodate the developing dentition


space btw jaws into where the teeth erupt is provided by growth at the

mandibular condyles (esp. molars)
-soft tissue development carries the mandible forward and down, and condylar growth fills the space to maintain contact with base of the skull


in infancy, ramus is located at the spot where what tooth will erupt

primary first molar


theory that explains why there is a strong tendency for mand anterior crowding in late teens and 20s is

late mandibular growth
-it says mand. incisors and maybe all mand. teeth move DISTALLY
-mandible undergoes more growth in this time than maxilla


most rapid losses in arch perimeter are usually due to

mesial tipping and rotation of the permanent 1st molar after removal of the primary 2nd molar


if a perm 1st molar is ext on a kid before the perm 2nd erupts, what do you do?

allow 2nd molar to erupt and mesially drift to close the space


when can a space maintainer be removed

when the perm tooth erupts through gingiva


most reliable indicator of readiness of eruption of a succedaneous (permanent) tooth and need for space maintainer is

extent of root development