6B Flashcards
Comprehensive Orthodontic Treatment
● Primary goal to
correct malocclusion & achieve ideal occlusion
○ Pts seeking comprehensive care often present with more severe malocclusion
● More precise control over tooth movement needed (more bodily movement than tipping)
○ Fixed appliances
○ Invisalign - more control than other removables, but not as good as fixed appliances
- Alignment & leveling
○ Initial archwire ⇒
NiTi (flexible with long activation spans & continuous low level force)
- Alignment & leveling
Initial archwire
■ SS too
stiff (before NiTi → multistranded SS and multi-looped ( ↑ length) archwires were used to increase flexibility)
- Alignment & leveling
○ Alignment: ⇒
initial correction by tipping
■ Minimal crowding → non-extraction; teeth tipped labially & buccally to increase arch
■ Moderate/severe crowding → extraction
- Alignment & leveling
○ Leveling:
■ Via extrusion -
continuous arches
● Extruding posteriors to fix deep bite → changes vertical dimension
● Easier; less complex biomechanics
- Alignment & leveling
Leveling
■ Via intrusion -
pass arches
● Intruding anteriors to fix deep bite → No change in vertical dimension
● Deep bite with excessive incisor display → anterior intrusion corrects deep bite & reduces incisor display at rest
● Deep bite with ideal incisor display →
either extrude posterior or intrude mandibular anteriors depending on pts face height
- A-P correction, space closure (in extraction cases), & determine optimal anchorage
○ By end of 2nd stage -
close remaining spaces in extraction cases, create class I molar & canine with ideal overjet and overbite
○ Space closure via sliding mechanics
■ Often a couple mm of space is left in
1rst PM area
■ Canine retraction first, then incisors -
● Retracting all 6 to close space requires too much anchorage
■ Disadvantage of sliding mechanics ⇒
Friction
● Friction causes tooth movement to take longer & lose anchorage (posteriors move more mesially)
■ Advantages of sliding mechanics ⇒
simple & easy to use; treatment of choice in uncomplicated cases
○ Space closure via retraction loop mechanics
■ Tend to be
more complex, traps food, and prone to distortion
■ Used for more complex cases
OSU recommendation - obtain
pano ~3-6 mo before finishing, so when you start 3rd stage, all these movements can be accomplished before the brackets are taken off
Root paralleling, torque, & individual tooth precise positioning
○ Individual tooth precise positioning -
1rst, 2nd, 3rd order control
■ Ensure midlines align
● Correcting midlines best done in 2nd stage when closing spaces
● Minor midline deviations can be corrected in 3rd stage with asymmetric elastics
Root paralleling, torque, & individual tooth precise positioning
○ Rooth paralleling:
■ When spaces closed, some tipping unavoidable, so roots need to be made parallel
● Can also be caused by errors on bracket positioning
Root paralleling, torque, & individual tooth precise positioning
○ Torque -
3rd order activation
■ When retracting incisors → sometimes distal tipping occurs, so torque (labial-lingual tooth movement) needed to ideally angle incisors
■ Rectangular arch wire must be used
Root paralleling, torque, & individual tooth precise positioning
Individual tooth precise positioning
■ Teeth nicely settled into occlusion
● After 2nd stage, ensure posteriors have cusp-fossa relationship (no posterior open bite) → via 2nd order activations (up & down movements) or elastics
● Tooth size discrepancies may prevent ideal settling
Goal ⇒ almost always want
Class I canine; & whenever possible also Class I molar, ideal overjet/overbite, no crowding/spacing, & good midline
● If PM extraction →
molars may not be Class I
Retention
Periodontal response:
● Widening of PDL
○ PDL recovers in 3-4 months
● Disruption of collagen fiber bundles
● Gingival & periodontal fibers stretched
○ Gingival fibers (esp. Supracrestal & circumferential fibers) take longer
Relapse due to growth:
● Late mandibular growth of concern (AP & vertical growth occur after adolescence)
○ Males until 17; females until 14-16
Removable retainers:
● Hawley Retainer -
most commonly used
Removable retainers:
Hawley Retainer
○ Holds teeth
labial-lingually in very precise position, but also allows for occlusal settling
Removable retainers:
Hawley Retainer
■ Limited tooth movement
possible - minor tooth position changes possible by adjusting wire
Removable retainers:
Hawley Retainer
○ Passive component ⇒
palatal/lingual acrylic base
Removable retainers:
Hawley Retainer
○ Active component ⇒
labial bow
Removable retainers:
● Vacuum formed retainer
○ Similar to invisalign
○ Advantages ⇒ esthetic & comfortable
○ Disadvantages:
■ Doesn’t last as long & settling not possible (teeth held precisely where they are)
■ Adjustments not possible if teeth shift & retainer doesn’t fit anymore
Two types of bonded fixed retainers:
● Braided ⇒
braided wire bonded to lingual aspect of teeth (often canine to canine)
○ Each tooth bonded to wire
○ Light braided twist wire allows for physiologic movement (more flexible?)
● Rigid ⇒ only bonded to the
terminal teeth (only canines)
○ Rigid bar rests on lingual surface & prevents relapse; easier to clean
○ 0.030 wire
Fixed retainers:
● Major indications ⇒
when intra-arch instability anticipated &/or prolonged retention desired
Fixed retainers:
Major indications
○ Maintenance of
lower incisor position
■ Significant rotation tends to relapse
Fixed retainers:
Major indications
○ Maintenance of
space closure
■ Large diastemas also tend to relapse
Fixed retainers:
Major indications
○ ———— maintenance in adult; pontic space maintenance
Extraction space
Fixed retainers:
● Advantages ⇒
esthetic (bc on lingual side); no compliance required; permanent retention
Fixed retainers:
● Disadvantages ⇒
Hygiene problem; maxillary lingual bonded retainer may interfere with occlusion
○ Does not maintain posterior transverse dimension
TAD;
impacted teeth; transplantation
Applications of TAD:
● Intrusion of
posterior teeth
Applications of TAD:
● Distal movement
of max. molars (in Class II correction)
○ Class II elastics less effective
Applications of TAD:
● Uprighting
posteriors
Applications of TAD:
● Space closure with
max. anchorage needs
Impacted teeth (often canines & 2nd molars impacted) ● Make space →
surgical exposure → attachment to tooth → orthodontic mechanics
Impacted teeth
● Treatment for impacted teeth depends on
crowding, location of tooth, & root formation status
Impacted teeth
● Biomechanics:
○ Eruption thru attached attached mucosa
○ Optimal force delivery necessary
■ If too much force, may cause ankylosis or devitalize the tooth
Class II with upper & lower crowding treatment options:
● Camouflage →
Extract lower 2nd PM & upper 1rst molars
Class II with upper & lower crowding treatment options:
● Surgery →
Extract upper 2nd PM (bc don’t want to bring upper incisors back) & lowe 1rst PM (bc you want to bring the lower incisors back & move the whole jaw forward)
Autotransplantation
● Root formation needs to be
½ to ⅔ formed
○ If completely formed → poor blood supply
Autotransplantation
● Light orthodontic forces to align
transplanted tooth
○ If orthodontic forces to heavy ⇒ root resorption, failed autotransplantation, ankylosis, or devitalization
Autotransplantation
● Advantage ⇒
allows for continued vertical bone development
continuous archwire for
leveiling
