Class 4 Flashcards
Major clinical problems of maxillary growth
Maxillary hypoplasia (class III)
maxillary prognathism (Class II)
Transverse deficiency
Restraining maxillary growth force magnitude
500-1000 g distributed over large bone areas and number of teeth
Restraining maxillary growth force duration
12-16 hours a day
Different from 6 hours for teeth movement
Restraining maxillary growth force frequency
Intermittent not continuous
Maxillary protraction face mask and reverse pull headgear
Intraoral components anchored on maxillary molars
6-8 months before 11 years old
3 mm of skeletal movement
Transverse Deficiency Palatal Expansion
Transverse maxillary deficiency targeting palatal suture
Seen in patients with Cl III Cl II with long problem
Rapid palatal expansion
1mm/day mostly for adolescents patients usually the entire course takes 2-3 weeks
Slow palatal expansion
1 mm/week may be used for late adolescent and young adult
_______ fo the mid palatal suture increases with age which increase the difficulty of suture expansion
Interdigitation
In adults the suture is either _____ or highly_______. Palatal expansion would produce mostly ______
Fused
Interdigitated
Dental movement
The mandible grows mainly
At the condyles-endochondral formation
And posterior and lateral surfaces -intramembranous formation
Functional appliances can _____ growth but may not ______
May accelerate growth
Increase final size
Unwanted dental effects of functional appliances
Lower incisor proclamation and upper incisor retroclination
May help reduce overjet though
Restraining mandibular growth chin cup headgear
Rarely used
Reducers mandibular protrusion by increasing face height
Widening the mandible
Symphysis
Can expand the dentoalveolus but not the basal bone
To expand the mandibular basal bone
Requires a surgical procedure—distraction osteogenesis
Distraction Osteogeneis
A surgically and mechanically induced bone regeneration process.
Osteotomy—bone fragments opened gradually
4 Sequential phases of DO
Latency
Distraction
Consolidation
Remodeling
Latency
The interval between osteotomy operation and then tart of distraction
Distraction
The period that distractor activation takes place
Consolidation
The post distraction period to allow for new bone formation
Remodeling
The period that the regenerated bone continues to remodel
Constituents of PDL
Mainly parallel collagenous fibers
Cells: fibroblasts osteoblasts mesenchymal stem cells and cells from the vascular structures
Blood vessel and nerve endings
Tissue fluids
The PDL is adapted to resist
Short duration forces
Prolonged forces to PDL induce
Remodeling of the PDL and adjacent bone
Force as low as ___ can induce tooth movement
2 gm
What is the main cell needed for tooth movement
Fibroblasts
______ is required for tooth movement beyond the PDL space
Bone resorption
What cells are required for bone resorption
Osteoclasts
What cells are normally and not normally in PDL
Fibroblasts present
Osteoclasts nope
Osteoclasts recruited from
Bone marrow and blood vessel
Bioelectric Theory
Bony changes caused by electric signals
1) Force induces piezoelectric signals
2) Bioelectric potential changes cell activity
Pressure Tension Theory
Bony changes caused by chemical signals
1) Pressure and tension alter blood flow
2) Formation and release of chemical messengers
3) chemical messengers change cell activities
Response to sustained light pressure: 1-2 seconds
Tooth displacement within PDL space
Response to sustained light pressure: 3-5 Seconds
Blood flow changes
Response to sustained light pressure: Minutes
Oxygen tension at compression side decreases —> prostaglandins and cytokines release
Response to sustained light pressure: hours
Chemical messengers cause metabolic change; second messengers release —> Osteoclasts recruitment FROM BLOOD, maturation and activation—> front bone resorption
Response to sustained light pressure: 2 days
Tooth movement beyond PDL space
Response to sustained heavy pressure: 1-2 seconds
Tooth displacement within PDL space
Response to sustained heavy pressure: 3-5 seconds
Blood vessels occluded on the pressure side
Response to sustained heavy pressure: Mintues
Blood flow cut off to compressed PDL
Response to sustained heavy pressure: HourS
Cell death in compressed area
Response to sustained heavy pressure: 3-5 days
Osteoclast recruitment FROM BONE MARROW inside alveolar bone maturation and activation —> undermining bone resorption
Response to sustained heavy pressure: 7-14 days
Tooth movement beyond PDL space
In response to heavy pressure osteoclasts were recruited from
Bone marrow, the opposite side of the PDL—> undermining resorption
The effect of force duration
Sustained force is required
-continuous force is not absolutely euiqred
4 hours per day
4-8 hours best clinical
The compression area is larger during _____ than _____—> greater force is needed to produce the same pressure
Translation
Tipping
Drugs that inhibit orthodontic movement
Bisphosponates
NSAID, Corticosteroids, prostaglandin inhibitor
Methods to accelerate tooth movement
Corticotomy
Vibration, phototherapy, ultrasound
Regional accelerated phenomen
Differential space closure
Anchorage control using different achnorage values
Using light force is important for this strategy
Stationary anchorage control
Only allow bodily movement of the molars which require stronger pressure
TADs
Temporary anchorage devices used to prevent unwanted tooth movement
