Ortho Exam II Flashcards
What are the 3 Growth Concepts?
Pattern
Variability
Timing
The Pattern growth concept refers to how proportional relationships change over ______
Variability is ______
Timing refers to _______ vs _______
Time
Quantitative (growth charts)
Developmental vs. Chronological age (Biologic Clock)
The cranial vault has what kind of growth?
Remodeling/growth occur where?
Bone is removed from inner surface and added to outer surface in response to what?
Intramembranous
Sutures
Growth of brain
Cranial base has what kind of growth?
Precedes the growth of the jaw and is not affected by what?
Endochondral
Growth of brain
Maxilla is what kind of growth?
Moves in what direction during growth?
Growth occurs where?
Intramembranous
Forward and Downward
Sutures connecting maxilla to cranium
Mandible has what kind of growth?
Direction?
Growth occurs where?
Endochondral and Periosteal
Downward and Forward
Condyles (endohcondral), Everywhere else (Periosteal)
Roof of mouth grows downward and forward by adding on oral and removing on ______
Nasal
Cranial Vault:
Cranial Base
Maxilla
Condyles
non condylar Mandible:
Intramembranous
Endochondral
Intramembranous
Endochondral
Periosteal
4 Direct measurements for assessing growth:
Craniometry - dry skulls
Anthropometry - soft tissue points covering bony landmarks
Cephalometric radiology - combines craniometry and anthropometry
3-D imaging - CBCT/MRI
2 Experimental measurements for assessing growth:
Vital Staining
Implant Radiography
Hemifacial Microsomia, deformed…
2 deficient soft tissues:
Occlusal plane…
external ear
Ramus/Mandible
Canted
Treacher Collins, what 2 areas underdeveloped?
Bilateral but maybe not…
_____ deformities
2 areas of hypoplasia:
Maxilla/Mandible
Symmetric
Ear
Malar/Mandibular
What is the most common congenital defect?
Cleft Lip/Palate
2 Craniosynostosis Syndromes:
Which is most common?
Crouzon’s syndrome (most common)
Cleidocranial Dysplasia
Crouzon’s Syndrome, hypoplasia where?
Crossbites where?
Crowding where?
Midface
Anterior/Posterior
Maxillary (severe)
Cleidocranial dysplasia, palate….
Deficient…
Teeth…
high arch
Premaxilla
multiple supernumerary/lack of permanent eruption
Primate space is seen in what dentition?
Maxillary:
Mandibular:
Primary
lateral incisors/canines
canines/first molars
Leeway space refers to what?
Space occupied by primary canines/molars often greater than succedaneous teeth
Leeway space in each Maxillary Quadrant:
Leeway space in each Mandibular Quadrant:
1-1.5 mm
2-2.5 mm
What is the greatest contributor to the Leeway Space?
To preserve Leeway space to alleviate Crowding, clinicians often use what?
Primary Second Molar
LLHA (lower lingual holding arch)
Early mesial shift refers to the mesial migration of the erupting mandibular ______
Occurring at what age?
Using up…
1st Molar
6 y/o
Mn primate space (leeway space)
Late mesial shift refers to the mesial migration of the erupting mandibular permanent first molar after what?
Using up the…
Occurring at what age?
Loss of Primary 2nd Molar
Leeway Space
11 y/o
Distalizers move the teeth where?
Backwards
3 types of Distalizers
Pendulum (T-Rex)
Temporary Anchorage Device (TAD)
Lip Bumper
Pendulum (T-Rex) distalizer moves what teeth?
Using what as anchorage?
Maxillary molars
Palate
TAD’s (temporary anchorage device) have many designs
True
A Lip Bumper uses lip pressure to move what teeth distally?
Mandibular Molars
Frankel II restrains pressure originating where?
Moves what?
What direction?
Buccal/Labial musculature
Mandible
Forward
What is the only tissue-borne device used to change functional/skeletal architecture?
Frankel II
7 Tooth-borne devices used to change functional/skeletal architecture:
Activator
Twin Block
Mandibular Anterior Repositioning Appliance
Herbst Appliance
Forsus Appliance T
Twin Force bite corrector
Headgear
Activator, advances the _______, may cover _______ teeth in acrylic to prevent eruption
Posterior eruption of lower may improve ______
mandible, maxillary
Deep Bite
Twin Block has separate ______
Function:
U/L components
Holds mandible forward
Mandibular Anterior Repositioning Device (MARA) places ______ on the Molars
Function (2 functions)
4 Crowns on Molars
Distalizes Mx molars, slight Proclination of lower incisors
Herbst Appliance redirects remaining Mandibular growth to be more ________
also….
Horizontal
Proclines mandibular incisors
Forsus Appliance requires…
Proclined _______
Attaches how?
Full braces
Mn incisors
Upper headgear to lower archwire
Twin Force bite corrector attaches to…
U/L archwires
3 Types of Headgear:
Cervical
High-Pull
Straight-Pull
Cervical headgear restricts…
High-pull headgear restricts…
Straight-pull headgear force is…
Anterior growth of Maxilla
Anterior/Downward growth of Maxilla
Directly distal to upper molar
3 ways to treat Deep Bites
Facemask
Chin cup (Mn protrusion)
Camouflage treatment (Mn protrusion)
Facemask for Deep Bites treats a _____ deficiency
Most effective prior to…
Must be worn…
Mx
10 y/o
10 hrs/day
3 types of Open Bites:
Habit
Dental
Skeletal
Direct bonding:
Indirect bonding:
etch, rinse, dry, sealant, air, light cure, brackets, remove flash
Impressions, draw guide lines on cast, bracket/resin, silicone tray over brackets/teeth, remove tray/brackts, clean pads, (unfilled resin)
Nasal bone growth is completed at what age?
10 y/o
Cranial growth:
Cranial base:
Maxilla:
Mandible
growth of brain
endochondral/synchondrosis
sutural/remodeling (intramembranous)
endochondral (condyle) else apposition/resorption
When is the optimal time to start orthopedic treatments?
PHV - peak height velocity (adolescent growth spurt)
PHV is closely related to what 2 indicators?
Calcification in hand (hand wrist films)
Cervical vertebrae shape
Compare the sesamoid, ulnar, hamate, and capping of first proximal phalanx and compare to _____ to determine approximately how much growth is left
Atlas
CVMS (cervical vertebral maturation stage) is viewed in what image?
2nd, 3rd, and 4th vertebrae indicate what?
PHV usually falls between what CVMS stages?
Lateral cephalogram
timing of peak of growth
II and III
Boney expansion in a transverse maxillary deficiency should be done when?
prior to closure of suture
Late Mn growth is most often seen in males and cause a patient to outgrow ortho Tx (esp in prognathic cases)
True
The nose and chin continue to grow throughout life
True
Mandible tends to grow horizontally
Mandible tends to grow vertically
Brachycephalic
Dolichocephalic
Fetal alcohol syndrome takes place in the _____ layer at day _____
Anencephaly takes place during ____ formation at day _____
Hemifacial microsomia (Treacher Collins) takes place at day _____ and is origin, migration, and interaction of cell populations
Primary palate (cleft lip/palate) day____
Secondary palalte (celft palate) day ______
Achondroplasia (Crouzon’s) day ____
17, germ layer
neural tube, 18
19-28
28-38
42-55
50 to birth
1st and 2nd Branchial arches affected in Hemifacial Microsomia
True
Treacher Collins comes from general lack of mesenchymal tissue
True
Cleft lip is the failure of fusion between median/lateral nasal processes and maxillary prominence in the _____ week of development
Cleft palate only is the incomplete fusion of secondary palate
6th
True
Craniosysostosis Syndromes occur when?
Due to the early closure of what?
What is the most common?
Fetal
Facial/Cranial Sutures
Crouzon’s
Superior/Posterior Mx sutures fuse prematurely
May extend into the cranium and distort cranial vault
Midface hypoplasia, bulging eyes, severe Mx crowding
Crouzon’s
Defect in bone resorption, heavy fibrous gingiva, supernumerary teeth, short broad skull, maxillary hypoplasia,
Cleidocranial Dysplasia
Mx permanent incisors are about __mm larger than primary incisors
Mn permanent incisors are about ____ mm larger than permanent incisors
8 mm
5-6 mm
Mx Primate space =
Mn Primate space -
- 7 mm
1. 5 mm
Greatest contributor to Leeway Space:
Primary second molar (2 mm)
Distal step in primary molars often leads to …
Mesial step leads to…
Class II
Class III
Teeth can be moved by light forces and extrinsic factors sustained up to 6 hours/day can alter equilibrium
True
Serial extractions should be done at what age?
Early mixed (6-8 years)
Should extractions be done on 3rd molars to alleviate crowding?
No
*no difference in anterior crowding when extracted
Lower bilateral space maintainer that can resolve anterior crowding
LLHA
Good for early loss of primary second molar, unilateral
Band and Loop
Loss of second primary molar prior to eruption of first permanent molar
contraindication:
Distal shoe
multiple missing teeth
Maxillary bilateral space maintainer, can be used for anchorage, hygiene problems
Nance appliance
Maxillary bilateral space maintainer, can be used for anchorage, can be adjusted to rotate molars
Transpalatal Arch (TPA)
Palatal expanders are best used prior to end of puberty and must hold expansion for ____ months to allow bone to fill
*Hyrax, Haas, Bonded RPE
6
W arch and Quadhelix are palatal expanders
False
*dental only
Distalizes Mx molars by using palate as anchorage, unilateral/bilateral, will get anterior flaring
Pendulum (T-Rex)
Lip pressure pushes Mn molars distal to regain lost space
Lip Bumper
Changes the posture of the Mandible by tissue (only one) or tooth-borne
Functional appliances
The only tissue borne functional appliance (moves Mn)
Frankel II
Advances the mandible, may cover Mx teeth in acrylic, posterior eruption of lower may help improve deep bite
Activator
Separate U/L components, (upper molars, lower pm’s) holds mandible forward
Twin Block
Four crowns on molars, distalization of Mx molars, slight proclination of lower incisors
MARA
mandibular anterior repositioning appliance
Redirect remaining mandibular growth more horizontal, increase total length of mandible, procline Mn incosors, does not require fixed braces
Herbst Appliance
Used for Class II correction, requires full braces, proclined Mn incisors, attaches from upper headgear to lower archwire
Forsus Appliance
Attached to U/L archwires and allows Mn lateral movements
Twin Force bite corrector
Cervical headgear restricts what?
High pull?
Straight pull force directed where
Straight pull can limit what?
anterior Mx growth
Anterior/downward Mx
distal upper molar
limits bite opening
Pseudo class III is more common than Class III at what age?
Anterior crossbite, forward shift of Mn, retroclined Mx incisors, proclined Mn incisors
8-12 y/o
Face Mask (reverse pull) used for what?
moste effective prior to what age
Class III malocclusion
10 y/o
Chin up was designed for Mn excess but is no longer used
True
3 strategies to Tx Deep Bite
Incisor intrusion
Molar extrusion
Incisor proclination
Dental open bite may be from habit
Skeletal open bite may be from
True
Excessive vertical growth, short Mn ramus, Mn over-eruption
4 basic components of fixed appliances
Brackets
Bands
Arch wires
Auxiliaries (ties)
Bracket dimensions:
No superior system, Dr. preference
.025 by .018 or .028 by .022
True
Self ligating bracket has a flexible component that entraps arch wire
It improved hygiene
True
True
Lingual appliances can treat any case buccal braces can
True
Ortho bands have better anchorage
Zinc phosphate cement can be a pulp irritant
True
True
4 ideal properties of Ortho arch wires
Hight strength
Low stiffness
High working range
High formability
Nickel-titanium wires resistant to _______, have low_____
Beta titanium is in between
Stainless steel has highest ______, lowest _____
permanent deformation, elasticity
True
modulus of elastisity, springback
Hawley retainer is very durable
Thermal plastic retainer is esthetic, easy to wear
True
True
Bonded retainers typically Mn canine to canine
True
3 strategies to relieve crowding:
Expansion/proclination of dentition
Reduction of tooth width
Extraction
3 considerations if expansion/proclination to relieve crowding:
Profile
Alveolar bone thickness
Overjet/Overbite
If reducing tooth width to reduce crowding, how much per tooth?
How much from 1st molar to 1st molar?
.5mm per side of tooth
5.5 mm max
When should Serial Extractions be done to alleviate crowding? (4 conditions)
7 mm or more crowding in Anteriors per Arch
U/L arch midlines coincident
Class I molars
Balanced Skeletal pattern
CD4
C primary canine
D primary 1st molar
4 first bicuspid
When does extracting primary tooth speed up eruption of succedaneous tooth?
When does it slow down subsequent eruption?
If 1/2 root formed
If extracted too early
5 ideal properties of arch wires
High strength
Low stiffness
high range
high formability
can weld/solder
Shape Memory Effect is ability to _______ shape
Occurs due to temperature (_____) or stress (____)
dependent shift in materials crystalline structure between 2 phases
Remember
thermoplasticity
super-elasticity
2 phases contributing to Shape Memory Effect through thermoplasticity and super-elasticity
Martensite (softer, low temp, better formability)
Austenite (harder, high temp, super-elasticity)
Wire used at First Stage (level and align)
Wire used at Second Stage (correction of molars/space closure)
Wire used at Third Stage (finishing)
Nickel Titanium (NiTi) - very light flexible wires
Beta Titanium (TMA) - heavier arch wires
Stainless Steel (SS) - low friction, best sliding
At what stage in are brackets not aligned?
First stage
*fully aligned at second, third stages
Gold and Cobalt-Chromium are not used much anymore as wires
True
Internal distribution of load (force/area)
Internal distortion produced by load (deflection/length)
Stress
Strain
Force-Deflection Curve, slope:
highest point:
Permanent deformation:
highest stress can withstand and return to form:
Breaks:
Stiffness
Strength
Proportional limit point
Yield strength
Failure point
Point around which a free body is perfectly balanced
Center of mass
Point of a tooth where a force application results in Translational Movement
Center of Resistance
Center of Resistance = Center of Mass when?
Free body
Center of resistance location single rooted tooth:
multi-rooted tooth:
1/3 of root length from CEJ
apical to furcation
Center of resistance is constant
Center of rotation is not constant
True
True
Rotation occurs when?
Force applies away from center of resistance
Uncontrolled Tipping (invisalign/spring retainers)
Center of rotation near center of resistance
*crown goes opposite apex
Controlled tipping:
Center of rotation:
Crown and Root tip in same direction
apex
All points on a rigid body move the same amount in the same direction
Translation
Keeps the crown in the ideal spot and moves only the root to the desired location
Root torque
Take out what teeth to alleviate crowding, retraction of incisors, some ant/post correction
Upper/Lower 1st PM’s
Take out what teeth for Class II correction
Upper 1st PM
Lower 2nd PM
Take out what teeth for Class III correction
Upper 2nd PM
Lower 1st PM
If take out the Upper PM’s only, will finish w/ Class I _______
Class II _____
canines
molars
Why would you take out a Lower central incisor?
1st molar extraction?
2nd molar extraction?
slight Class IIIj
if compromised and 3rd molar forming
1st molar distalized
7 mm or more of crowding in the anterior areas per arch
coincident upper and lower midlines
class I molar relationship
balanced skeletal pattern
Serial Extractions
Serial extractions can be complicated if molars are class III or II, unbalanced skeletal pattern, unequal crowding in arches, over 2 mm midline discrepancy, open bite, or deep impinging bite
True
When to do serial extraction?
When permanent laterals erupt rotated or are blocked from eruption
If the permanent laterals are rotated/blocked, then extract ______
primary canines
When permanent laterals erupt (rotated/crowded)
Extract primary canines
6-12 months, extract primary 1st Molars
Extract permanent 1st PM’s
Ortho
Serial extractions
CD4
(Canines, 1st primary molars, permanent 1st PM’s)
The stress/strain response to an external load
Elastic behavior
2 bracket sizes are .018 and .022
True
Round wires cause all kinds of movement except?
Rectangular wires can control?
Torque
Torque
In 2nd Stage Ortho, brackets are fully aligned and the molar relationship is guided via what 2 factors?
Differential growth of jaws
Differential movement of U/L teeth
Root parallelling
Incisor torque
Correction of overjet/overbite
Correction of midline
Final settling of posterior occlusion
Third Stage Ortho
Ni-Ti is good for leveling and aligning due to low stiffness and high range
True
What has the highest friction of all the wires?
Beta Titanium (TMA)
Stainless steel is _____ chromium and _____ nickel
18% chromium
8% nickel
Stainless steel is softened by ______
Hardened by ______
annealing
cold working
Most elastics lose elasticity in 12 to 24 hours
Latex elastics last 4-6 times longer
True
True
1st law
2nd law
3rd law
inertia
F=MA
equal and opposite rxn
The center of resistance in constant and is located about 1/3 of the root length from the CEJ
True
The center of rotation is constant
False
*determined by type of movement
Moment is the tendency for a tooth to rotate around the center of resistance
True
Brackets are the only way to bring multiple forces to a tooth for Controlled Tipping
True
In root torque, the center of rotation is found where?
Incisal tip
Couple is created by two equal/opposite non coplanar forces acting on an object and are the only force systems that create ______
pure rotation
Variation in bracket slot location/orientation is known as what?
Prescription
3 reasons there is more to straightening teeth than presciption
slop
wire rigidity
biomechanics
Pure translation is difficult b/c center of resistance is in the bone
True
What is the most common treatment of Deep Bites?
Molar extrusion
