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53 Cards in this Set
- Front
- Back
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Dr. Andrew's 6 keys to normal occlusion
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1. D of max 1st DB cusp contacts M of mand 2nd MB cusp
2. crown angulation (all point toward midline) 3. crown inclination: ant->labial. max post->lingual (evenly). mand post->lingual tilt, progressively increasing 4. no rotations 5. no space, all in contact 6. occlusal plane flat to slight Curve of Spee |
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Angle's Postulate (2)
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1. upper 1st molars are the key
2. the MB cusp of upper molar should occlude in buccal groove of lower |
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normal occlusion (2)
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-normal molar relationship
-line of occlusion is correct |
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Class I Malocclusion
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-normal molar relationship
-line of occlusion is INcorrect |
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Class II Malocclusion
Divisions |
-lower molar is distally positioned
-line of occlusion not specified CII DivI: - protruding upper incisors CII DivII: - retruding upper incisors |
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Class III Malocclusion
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-mand molars are mesial
-LoO not specified |
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what are malocclusion subdivisions
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-can be diff on opp sides
eg. "CII Div I Subdivision Right" |
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Angle's CII Jaw relationship (2)
growth pattern |
-mandible distal to max
-usually w/ CII molars, but can be CI -downward and backward (mand) |
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Angle's CIII Jaw relationship (2)
growth pattern |
-mand mesial to max
-usually w/ CIII molars -disproportionate forward growth of mand |
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Proffit and Ackerman's 5 major characteristics of malocclusion
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-facial proportions, esthetics
-arches aligned, symmetrical - skeletal and dental relationships along the transverse plane -anteroposterior plane -vertical plane |
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divergence:
def classifications |
-ant/post inclination of lower face relative to forehead
-post divergent, straight (orthognathic), or ant divergent |
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dental crossbite
skeletal crossbite |
-teeth in wrong place
-palate too narrow |
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overbite
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-deep bite. excessive overlap of ant teeth
-(should contact at cingulum) |
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over jet
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-horizontal space btw upper/lower incisors
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3 major categories of ortho records
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-health
-alignment, occlusal relationships -facial, jaw proportions (cephs and photos) |
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inadequate attached gingiva around crowded incisors indicates the possibility of
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-tissue dihiscence developing after teeth are aligned
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Evaluation of Jaw (4)
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-mastication difficulties
-swallowing (infantile vs somatic?) -speech problems -jaw function |
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Micro-Esthetics:
tooth proportions (2) |
-golden proportion (width relationships)
-width of tooth should = 80% of height |
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Malocclusion causes:
embryologic (2) |
- <1%
-genetic disturbances, environmental insults |
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Malocclusion causes:
skeletal growth disturbances (3) |
-intrauterine molding
-trauma to mand during birth -childhood fractures to jaw |
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Malocclusion causes:
muscle dysfunction |
-bone formation depends on muscle activity. Growth should carry jaw downward and forward
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Malocclusion causes:
acromegaly |
-excessive mand growth
-condylar cart proliferation |
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Malocclusion causes:
hemimandibular hypertrophy (4) |
-unknown etiology
-unilateral excessive growth of mand -condylar cart proliferation -common in females 15-20 |
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cleidocranial dysplasia (dysostosis) (3)
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-congenital defect
-deficient formation of skull and clavicle -involves multiple supernumerary teeth |
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Malocclusion causes:
genetic (2) |
-disproportion btw size of teeth and size of jaws --> crowding/spacing
-disproportion btw size or shape of upper/lower jaws --> improper occlusion |
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rate of malocclusion in the US is _________ compared to the rest of the world
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-very high!!
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Adenoid Facies
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-altered respiratory pattern (eg. breathing through mouth) could change posture of head, jaw, tongue and :. alter jaw growth or tooth position
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who established cephs in the US?
when |
-Broadbent
-1931 |
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Standard Ceph arrangement (2)
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-source to subject (midsagittal plane) = 150cm (5ft)
-pt (MS plane) to cassette = 15cm |
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teeth move when...(3)
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-cells in PDL respond to pressure
-bone is resorbed/laid down -PDL is reorganized |
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what causes bony changes?
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-pressure-> cell shape distortion-> bioelectric changes
...such as: -pizoelectric bursts (??) -ionic migration across cell membrane -fluid flow, streaming potentials |
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osteoblasts respond to ______ and _____ bone
osteoclasts respond to ____ and _____ bone |
-tension; build
-pressure; resorb |
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Effects of applied light force (3)
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-osteoclasts w/in PDL differentiate
-osteoclasts attack LD (lamina dura) and remove bone -movement begins |
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Effects of applied heavy pressure (7)
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-blood flow stopped
-cells disappear -PDL becomes avascular?? -sterile necrosis: hyalization -after delay of several days, osteoclasts in marrow spaces attack underside of LD -rapid tooth movement -ossible damage to PDL, root |
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force duration:
force must be applied for at least _____ in order for ______ |
-4hrs
-neucleotide levels in PDL to increase, ie. cellular differentiation |
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force duration for clinical threshold for tooth movement
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- 4-8hrs
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orthodontic relapse:
factors (3) |
-force duration, distance of movement, functional problems
-gingival/periodontal fibers -time period of bone remodeling after movement |
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Hawley retainer
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-most common
-removable w/ metal wire |
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retention needed for remodeling of:
periodontal fibers gingival fibers bone |
-90 days
-232 days to years -6 months |
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Biomechanics: center of resistance
def 1-root teeth multi-root teeth factors in mouth |
-point of concentrated resistance to movement. Center of free object, but it changes when the object is embedded in something
- 1/4-1/3 distance from CEJ -> apex - furcation -alveolar bone height and root length |
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Biomechanics: moment
def importance equation |
-tendency to rotate around CR
- a force not passing through CR produces both linear and rotational movement - Moment = Force x perpendicular Distance from CR (M=FxD) |
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biomechanics: couple
def importance |
- 2 forces equal in magnitude and opposite in direction
-produces pure rotation around CR |
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biomechanics: couple
wire in angulated bracket rectangular wire in a bracket slot (??) |
-angulation (2nd order)
-inclination (torque, 3rd order) |
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tipping movement:
type of movement, type of force (2) creates PDL force distribution force range |
-simplest movement
-single force -creates rotation around CR -only 1/2 of PDL is loaded -forces high at apex and alveolar crest, 0 at CR -force 50-75g |
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Biomechanics: bodily movement
type of force effect PDL force range |
- 2 forces
-apex and crown move together -uniformly compresses PDL - 79-120gm (2x force for tipping) |
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Biomechanics: Intrusion
force location force range |
-small area at apex
- 10-20gm (light force) |
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Biomechanics: Extrusion
PDL force range |
-ideally no compression, only tension
- 50gm (same as tipping) |
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Biomechanics: controlled tipping (CT)
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-motion of object w/ 1 force away from CR and a counterbalancing couple (CBC) to regulate rotation
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optimum ortho movement is produced by __________
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-light continuous force
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3 properties of beam materials
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strength = stiffness x range
(range = length) |
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Biomechanics:
the more ______, the springier the wire. the more ______, the stiffer the wire |
-horizontal the slope
-vertical the slope |
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Factors for wire load/deflection rates (3)
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-modulus of elasticity (intrinsic)
-length (extrinsic) -cross-section area (extrinsic) |
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types of ortho arch wire (3)
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1. stainless steel
2. beta-titanium (BT) 3. nickel-titanium (NT) |
