week 4 Flashcards
how is the maxilla attached to the cranium
Numerous sutures
maxillary hypoplasia leads to what classification
Class III
maxillary prognathism leads to what classification
Class II
a transverse deficiency leads to what classification
Posterior crossbite
do you need more or less force for orthopedic or orthodontic foces
More for orthopedic (500-1000) because distributed over large bone area and bumber of teeth
how long do you have to restrain maxillary growth
12-16 hours a day (not 6)
how is force frequency applied for maxillary growth restraint headgear
Intermittend (not cont)
what headgear is used to restrain maxillary
High pull
cervical pull
Combi
what do maxillary protraction face maska and reverse pull headgear attach to
Maxillary molars
Ideal: temporary implants and ankylosed teeth
when is maxillay protraction face mask and reverse pull headgear
10-11 years old for 6-8 months
how much change can maxillary protraction-face mask and reverse pull headgear move the skeleton
3mm of skeletal movement
when is a maxillary transverse deficiency seen
Seen in patients with Class III malocclusion
seen in patients with Class II with vertical (long problems)
isolated problems
when do you use a palatal expaspander
To correct maxillary transverse deficiency
what is the target of palatal expansion
Midpalatal suture
how fast is rapid palatal expansion
1mm/day over 2-3 weeks
when do you use rapid palatal expansion
adolescent patients
what type of expanders are used for preadolescent children and preschool for palatal expansion
W-arch and Quad helix appliances (not jackscrew-type expanders)
how fast is slow expansion
1mm/week
when is slow expansion done
used for late adolescent and young adults
what is done after palatal expansion
3-6 months of retention for bone consolidation
why is it difficult to do RPE in older people
Interdigitation (not fusion) of midpalatal suture increases with age
what is the comparison between skeletal and dental movement in rapid palatal expansion
50% skeletal
50% dental
what happens in RPE if the suture is highly interdigitated
Production of mostly dental movement
how can you do RPE in adults
Surgically assisted RPE
how does the mandible groe
Mainly at the condyls (endochondral formation)
posterior and lateral surfaces (intramembrouanous formation)
what does mandiblar hypoplasia/retrognathism lead to in classification
Class II
what does mandibular prognathism lead to in classification
Class III
what does a transverse constriction of the mandible lead to
Brodie bite
how can we affect mandibular growth
Functional appliances can accelerate mandibular growth but may not increase the final size of the mandible
what is the typical outcome of functional appliances to stimulate mandibular growth
Combined skeletal and dental changes
what accounts for the inconsistent skeletal effect of mandibular growth control
loading pattern
what negative consequence do functional appliances have on the teeth
Lower incisor proclination
upper incisor retroclination
when would functional appliances not be a good choice
when patient has already proclined lower incisors and retroclined upper incisors
why don’t we use mandibular growth chin cup headgear
Reduced protrusion by increasing anterior face height rather than shortening size
what is the most common treatment for mandibular prognathism
Mandibular surgical setback after cessation of mandibular growth
when does the symphysis of the mandible fuse
fuses at 7-8 moths
what can mandibular expansion appliances expand
the dento-alveolus, not the basal bone
what does expansion of the mandibular base bone require
Surgical procedure via distraction osteogenesis
what is distraction osteogenesis
used to lengthen bones via bone fragments gradually opening to create a gap and remodeling
what is distraction histogenesis
Adaptation of soft tissues (blood vessels, ligaments, muscles, nerves)
what are the 4 major sequential phases of DO
latency
Distraction
Consolidation
Remodeling
what is latency
Interval between osteotomy operation and start of distraction
what is distraction
Period that distractor activation takes place
what is consolidation
Post-distraction period to allow for new bone formation while appliance is still in place
what is remodeling
Period that the regenerated bone continues to remodel after appliance removal
what is the stability of different symphyseal distractors
Hydrid>tooth borne>bone borne
what is the reliablity of transferrring expansion force to bone of different symphyseal distractors
Tooth borne>hybrid
what can we change in the skeleton without using surgery
Maxillary protrustion
Hpoplasia and trasverse constriction
mandibular retrognathia
can you use growth modification to fix severe skeletal problems
No(must do surgery)
what is the soft tissue connecting teeth to the alveolar bone
PDL
how big is the PDL
.5mm in width
what are the fibers of the PDL
parallel collagenous fibers
what are the Cells of the PDL
fibroblasts
Osteoblasts
mesenchmal stem cells
Cells from the vascular structures
what strucutres are present in the PDL
Blood vessels and nerve endings (unmyelinated for perception of pain, pressure and position)
what is the roll of the tissue fluids in the PDL
viscoelastic elements
Dampening effects
what kind of force does the PDL resist
Short duration forces(act as a shock absorber)
what do prolonged forces on the PDL do
Remodel PDL and adjacent bone
what is needed to be remodeled for tooth movement
PDL fibers (especially the sharpey’s fibers)
what does most of the remodeling of the PDL fibers
Fibroblasts already present in the PDL
what needs to be done for the tooth to move beyond the PDL Space
Bone resorption
what is the roll of the alveolar bone
Support teeth and keep them relatively stable
how do osteoclasts resorb bone
Produce acid and enzymes
where do osteoclasts come from
Hematopoietic stem cells-> monocytes-> osteoclasts
(not in PDL need to be recruited from BV or bone marrow)
what is the bioelectric theory for tooth movment
Bony chnaged by electrical signals that then chage cell acitivty
what is the pressure-tension theory
Pressure and tension alter blood flow causing a release of chem messengers
- chem messenger change cell activities
what happens in 1-2 sec after sustained light presssure
Tooth displaced within PDL
what happens in 3-5 seconds in sustained light pressure
blood flow changes
what happens in minutes of light presssure
Ozygen tension at compression side decreases leading to a release of prostaglandins and cytokines
what happens hours after sustained light pressure
Chemical messenger cause metabolic change and second messengers (such as cAMP) release
- osteoclast recruitment (blood flow), maturation and activitation-> frontal bone resorption
what happens 2 days after sustained light pressure
Tooth movement beyond the PDL space
what happnes in 1-2 sec after heavy pressure
Tooth displaced in PDL space
what happens 3-5 sec after heavy pressure
Blood vessels occluded on the Pressure side
what happens after minutes of heavy pressure
Blood flow cut off to compressed PDL
what happens after hours of heavy pressure
CEll death in compressed area
what happens after 3-5 days of heavy compression
Osteoclasts recruitment from bone marrow in the alveolar bone, mature and activate to do undermining bone resorption
what happens after 7-14 days of heavy pressure
Tooth movement beyond PDL space
where do Osteoclasts come from in light and heavy pressure
Light: blood flow
heavy: bone marrrow in alveolar bone
what resorption is done in heavy and light pressure
Light: frontal bone resorption
heavy: undermining bone resorption
what kind of force is needed to move tooth
Sustained force is required but continuous is not absolutely necessary
how long should you apply force to induce movement
4-8 hours (longer is more efficient
what determines the compression/tension regions
Force application pattern
what has larger compression area, translation or tipping
Translation`
do adults or kids have faster tooth movement
Kids are faster
why do kids have faster tooth movement than adults
children have remaining alveolar growth and relatively less dense bone
what is the effect of osteopetrosis and osteoporosis on tooth movement in the jaw bones
osteopetrosis slows down tooth movement
osteoporosis accelerates
does the mandible or maxilla move the teeth faster
Maxilla is faster due to less dense bone
what drugs can inhibit ortho movement
Prostaglandin inhibitor: NSAID, corticosteroids
Bisphosphonates
what can be done to accelerate tooth movement
Local injury (regional acceleratory phenomenon)
Corticotomy assisted tooth movement (Wilckodontics)
vibration
phottherapy
ultrasound
what is the roll of anchorage
Resist unwanted tooth movement and to resist reaction force
what is the goal of efficient orthodontics
Maximizing tooth movement and minimize unwanted reactionary effects
does incraseing pressure increase tooth movement
Yes, but only to a certain extent
what does optimal force depend on
the tooth and the pressure produced at the PDLs
what is reciprocal space closure
where two teeth are pulled together with no anchorage
how do you do Differential space closure
Use anchorage control using different anchorage values of different teeth
what is an anchorage valve
Depends on the root surface
what force should be used in differential space closure
Light force
what is stationary anchorage control
only allows bodily movement of the molars to pull the anterior teeth forward
what is a skeletal anchorage
Uses Temporary anchorage devices(TADs) to prevent unwanted tooth movement
how does the pulp react to ortho
Generally is minimal
why might the pulp lose vitality
due to previous trauma (ask about pt’s dental history)
what teeth can be moved ortholy
Proper RCT
what teeth should be avoided in major tooth movements
CaOH filled teeth in the anterior with open apices
is root remodeling a common theme of ortho
yes. but most people aren’t severe
where may permanent loss of root surface occur
Primarily at the apex
what teeth tend to have root resorption
Incisors and second premolar
how common is severe root resorption
1-2%
when is root resorption severe
greater than 1/4 root gone
what are the risk factors for excessive root resorption
Abnormal root morphology (conical roots, pointed apices, dilacerations)
Prolonged treatment time, excessive and prolonged ortho forces
Genetic predisposition
History of root resorption
how much alveolar bone height is loss due to ortho
less than .5mm
what happens if perio conserns during treatment
Evaluated/addressed by perio and active disease should be controlled prior
