Orthognathics Flashcards
Miloro 2015 (98 cards)
1
Q
What are the landmarks of facial thirds?
How is the lower third split?
Which third do orthognathic procedures usually affect?
A
Vertical thirds:
trichion ( Hairline in midline) -> Glabella - > Subnasale -> menton
Subnasale -> Oral commisure = 1/3
Oral commisure -> menton = 2/3
Most orthognathic procedures affect lower 1/3rd.
2
Q
Waht are the proportions of facial fifths?
A
Horizontal fifths:
Based on length of eyes
ICD ~ Alar width
OCD~ Medial limbus distance
3
Q
Judging Asymmetry
A
Use bite stick on each arch separately and compare cant of each arch to interpupillary lines
4
Q
What is the best clinical examination to determine maxillary position?
A
Incisor display at rest (treat to this!)
- normal 2.5 +/- 1.5mm
- in animation smiles include 80-100% of crown +2-4 mm of gingiva
Other factors include
- length of clinical crown, length of upper lip, amount of vermillion,
- Age lowers smile line by 2-3 MM so it is better to overcompensate (show more incisor)
5
Q
CR what is it?
CO what is it?
A
Centric Relation - most anterior superior position of condyle (independent of tooth contact)
- hard to reproduce - in surgery usually push condyles most posterior and superior
- anesthesia cause laxity of the joint due to lack of muscle tone and stripping of soft tissues.
Centric occlusion = habitual occlusion
6
Q
What is the normal Orthognathic profile angle?
Wher is frankfort horizontal
A
Convex - 13 degrees from glabella to subnasale to menton.
Porion ( EAC) to orbitale.
7
Q
Angles of profile? What are normals of NLA, FNA, LMA, NCT angles?
A
FNA = frontonasal = 125-135 NLA = nasal labial= 90-95 LMA= Labiomental = 110-120 NCT= neck chin throat =120
8
Q
Chin position from profile is based on
A
Zero meridian line ( line perpendicular to FH that passed through nasion) - Pogonion should be +/- 4 mm from this line
9
Q
Absolute vs relative transverse discrepancy?
A
Relative discrepancies can be corrected by moving jaws forward and/or back.
10
Q
What is correct diagnosis in patient who is class three with anterior open bite and transverse discrepancy (lateral ceph showing maxillary deficiency)?
A
Maxillary AP deficiency
11
Q
Rocky Mountain transverse analysis
A
used to analysis maxillary transverse discrepancies form J point to J point on PA Ceph
12
Q
Patient presents with class I on the left and class II occlusion on the right without a midline discrepancy. What will be needed?
a. Segmental osteotomy
b. body ostectomy
c. extraction of teeth
d. rotationall SSO and VRO setback
A
Extraction of teeth
- neededfor 1. crowsding, 2 compensatio needed, 3. correcting curve of spee.
13
Q
correcting curve of spee (curve from posteriro to anterior)
A
In order to fix a large curve of spee ( deep) you need 1.25 mm of space for every 1 mm of correction.
14
Q
How can you increase arch space (4 ways)
A
- Premolar extractions
PM1 removed if you want ti retract anterior teeth
PM2 removed if you want to protract the posterior teeth - Widen arch with RPE or O(orthopedic) Expansion
- Inter-proximal reduction
- Incisor proclination
15
Q
Which is contraindicated in the presurgical orthodontic tx of malocclusion II elastics?
a. Class II elastics
b. Class III elastics
c. Decompensate retroclined upper incisors
d. decomponesate proclined lower incisors
A
Class II elastics (class II elastics correct class II bites by pulling from anterior of upper to posterior of lower; class III elastics correct class III bites by pulling opposite) would not be used so orthodontist can maintain the overjet that is there currently for decompensation.
16
Q
What reference is used to decide if you want to extract lower premolar one vs lower premolar two?
A
Occlusal plane must be maintained
- take out PM1’s with class III elastics to retract lower anterior
- take out PM2’s with class II elastics to protract posterior teeth
17
Q
A 16 yo with class II malocclusion is beginning orthodontics with LeFort advancement and mandibular setback. There is significant crowding in both arches with dental compensations. What pattern of premolars should be extracted?
a. Max PM1 and Mand PM2
b. Max PM2 and Mand PM1
c. Max and Mand PM2
d. Max and Mand PM2
A
A. Maxillary PM1 and Mandibular PM2
Lefort advance + setback = Class III
Class III = compensated teeth (retroclined mandibular incisors and proclined maxillary incisors) - ext PM1 max to retract maxillary incisors and ext PM2 mandible to bring lower posteriors forward.
Class III patient will finish in a class II molar occlusion
Class II = deficient mandible with compensated teeth (proclined mandibular incisors and retroclined maxillary incisors) - EXT PM 2 Maxillary and EXT PM1 mandible to retract anteriro teeth
Class II patient will finished in a class II molar occlusion.
Hard and Fast:
EXT PM2 if you want to maintain incisor postion in that arch ( if they are retroclined or relative normally)
EXT PM1 if you want to retract incisors in that arch (they are proclined)
18
Q
Orthodontic goals and what are 3 exceptions
A
Level, align, decompensate
Exception to this rule
- Class II deep bite with short face
- prefer tripod occlusion to maintain curve of spee and lengthens facial height - close posterior open bites with elastics - planned segmental surgery
- Iowa/Casko spaces (between k9 and laterals) used to maximize mandibular movement and can close after with ortho.
19
Q
What is bolton analysis used for?
A
tooth crowding and need for extractions
- Anterior vs overall analyses
- compares tooth width to arch length
20
Q
After 2-jaw surgery, the maxillomandibular complex is noted to be off axis what caused this?
a. condyle note seated properly
b. rigid fixation failure
c. dental interferences
d. inaccurate model surgery
A
d. inaccurate model surgery
21
Q
Maxillary surgery is usually completed first in most double jaw surgeries. When you the mandible be completed first (5 reasons)?
A
- Steep occlusal plane with plan for maxillary downgraft. (huge open bite)
- Inaccurate interocclusal records.
- Difficulty with intraoperative MMF in intermediate position (intermediate splint is too bulky or OJ to large for wires).
- basically too large a class two or too large a class III. - TMJ surgery concomitantly
- Uncertain in condylar position ( usually due to condylar resorption)
22
Q
Segmental Surgery requires (for stability) 2 options?
A
- Transpalatal arch wire
2. Fine splint with partial palatal coverage
23
Q
What causes variations in ceph analyses?
What is the center of rotation of the condyles?
a. Condylion (Co)
b. Articulare (Ar)
c. Center of condyle (c)
d. Instantaneous center of rotation (ICR)
A
cranial base variations
D. ICR - center changes all the time
- Dolphin uses condylion (most posterior superior aspect of condylar head)
24
Q
What is Steiner analysis used for?
A
Evaluating incisor position
- SNA, SNB, ANB
25
Rarely uses final splint why?
To avoid anterior open bite - tough to close
26
When does skeletal maturity occur in the female patient?
a. 11-13
b 14-16
c 16-18
d. >18
B.14-16
Girls 15-17
Boys 16-18
27
Other than serial lateral cephs what is the best method for estimating facial skeletal maturity?
C-spine evaluation (Cervical Vertebrae 2) (most accurate)
- increased convexity in lower border of C2
- height becomes taller than wider (c2)
- Shape goes from wedge -> square -> rectangle (mature)
Serial cephs q6m
Hand wrist not as accurate but uses Fishman maturation index
28
Can you do surgery during growth?
yes - for low angle class II hypoplasia
29
What is envelope of discrepancy?
It is a chart showing three circles that correlate to the amount of movement possible with that method.
```
Smallest = ortho
Medium = ortho with growth modification (herbst/head gear)
Largest = ortho and surgery
```
30
TMJ and orthognathics?
Anteriro disc displacement associated with class II malocclusion
Must treat preexisting TMJ disease prior.
Tough to get CR of TMJ due to general anesthesia, supine position, muscle stripping.
31
Epidemiology of Malocclusion
Class II is more common but less often requires surgery.
Class III is much less common but usally requires treatment
32
BSSO History
Dalpont modification?
Hunsuck?
Trauner and Obwegeser in 1957
Dalpont - 1961 modification to bring vertical ostectomy forward to first molar - allows for more bony contact = increased success
Hunsuck - 1968 modification to bring horizontal medial ostectomy to retrolingular depression
33
During SSO, injury to the IAN can be minimized by placing the vertical osteotomy lateral to which area?
a. 1st molar
b 2nd molar
c. 3rd molar
d. retromolar pad
a. 1st molar
| - CT studies show this is when IAN is most lingual (4.1mm), cortex is 2-3 mm
34
Is L configuaration or straight configuration more stable?
L is more stable, but bicortical screws can widen intercondylar distance.
Single monocortical plate along champy's line of tension is effective. along external oblique ridge, and allows for some play.
35
Prescence of third molars in SSRO results in ?
a. Less IAN injury
b. more bad splits
c. more stable fixation
d. less operative morbidity
b. more bad splits
- also increased risk of poor fixation and IAN/LN injury
- remove 9-12 months prior
Precious 2012 wrote a study refuting this
36
seating condyle in class II vs class III patients?
Class II = "firmly"
| Class III = looser
37
Following SSO advancement and elimination of bony interferences, a bony gap remains between anterior extent of the proximal and distal segments. If a lag screw is used for fixation what happens?
a. distal segment advances anteriorly
b. anterior open bite develops
c. medial condylar displacement
d. lateral condylar displacement
d, lateral condylar displacement
- lag screws will bring segments together in this case it will bring the anterior portion of the proximal segment closer to the distal segment (more medial) kicking out the posterior of condylar portion laterally.
38
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What causes a IAN paresthesia with VRO?
a. Setback > 10 mm
b. Medial displacement of proximal fragment
c. Excessive medial dissection
D. Use of rigid fixation
```
VRO used only for setbacks and useful for asymmetries.
c. Excessive medial dissection
39
What is the best osteotomy design for avoiding the IAN during VRO?
a. Depth of sigmoid notch to antegonial notch
b. 5mm posterior to antilingula
c. mid ramus
d. from depth of sigmoid to any point in the posterior border above the gonion.
b. 5mm posterior to antilingula
Better v shaped mandible - u shapped are tough to access and visualize
- the mandibular foramen is located 7mm from the posterior boder of the ramus in 3% of patients.
- use oscilalting saw (7mm depth) with LeVassaeur-Merril retractors for adequate depth
40
Complete stripping of which muscle will cause condylar sag in a VRO?
a. Masseter
b. Temporalis
c, L pterygoid
d. M pterygoid
d. M. pterygoid
VRO - strip widely laterally minimal medially, opposite of SSO.
VRO - requires 3-4 week MMF if unable to fixate
VRO is from notch to inferior border
41
17 yo with mandibular hyperplasia and a class III deformity presents with 4mm of reverse overjet. CBCT shows v shaped mandible with divergent rami. which procedure for setback would cause the greatest change in intercondylar width?
a. BSSO with lag screw fixation
b. VRO with lag screw fixation
c. Inverted L osteotomies with miniplates
d. C osteotomies with miniplates
a. BBSO with lag screws
see prior
42
Which artery provides the greatest blood supply to the down fractured maxilla?
a. Nasopalatine
b. Descending palatine
c. Ascending palatine
d. Maxillary artery
C. Ascending palatine
Branch of facial artery (b. of external carotid)
- Ascending pharyngeal also provides blood supply via external carotid artery branch.
- Bell showed this in 1975
- down fracture loses DPA and nasopalatine both from maxillary artery
43
Risk of avascular necrosis?
| 6 risks
- Segmental procedures
- large movements >8mm
- expansion
- lengthy surgery (pressure on mucosa from fingers or splints)
- palatal mucosal tears
- history of smoking
44
Durign a 3 piece LeFort you notice blanching of the maxillary gingiva. On morning rounds the area appears dusky and cyanotic. What do you do?
a. Immediately go to OR for explorations
b. Immediate HBO tx
c. Removal occlusal splint and assess for impingement on palate.
d. Reassess in 24 hours,.
C. Remove splint
Tx: = remove MMF, removal splint palatal coverage, provide adequate IV fluid and pRBC's to increase O2 capacity
can try HBO to limit progression but will require debridement, grafting and implants.
45
What procedure should be completed last for LeFort?
Pterygoid plates
- reasoning - if a lot of bleeding after this can down fracture and visualize quickly.
- Osteotome is 15mm wide. Maxillary artery is 25mm from notch = 10 mm of safety
- Maxilalry artery is 16 mm superior to nasal floor where it enters the pterygopalatien fossa and gives rise to DPA
- Anterior inferior and medial direction of osteotome.
- Plates fracture at tuberosity at Pterygoid-Max junction, or through plates - can cause orbital issues.
46
Internal vs external reference points, which is more accurate?
External is more accurate = place 8-11 mm to be safe at nasion
47
What is the average distance from DPA to piriform rim?
2.5 cm - so go <2.5 cm when applying lateral wall ostetome.
OMS reference guide says DPAs located 35 mm posterior to piriform rim and to stop at 3 cm.
48
Tessiers are used for?
stretching soft tissue after down fracture of maxilla
49
Segmental Osteotomy placement
avoid midline = bone thickess, mucosa thinnest
go paramidline = thin bone thick mucosa.
Try to keep segmental between PM and K9.
50
Upon release of MMF following LeFOrt Osteotomy there is an anterior open bite. What caused this?
a. Failure for mobilization of maxilla
b. residual bony interferences
c. failure to seat condyles
d inaccurate model surgery
c. Failure to seat condyles.
- in MMF if condyles are not seated - when released muscles pull mandible upwards creating a fulcrum on posterior teeth and anterior open bite
51
Alar width preserved with?
Vermillion show preserved with?
Reduce nasal spine?
Alar cinch
V-y closure
Milloro doesn't reduce nasal spine as it affects tip support, he will reduce nasal septum to avoid deviation
52
Pt arrives at ED 2 weeks s/p LeFort impaction by another surgeon. Postop course was uneventful until profuse bleeding led them to call 911. Pt is stable on exam except hypotensive and tachycardic. Bleeding stopped without intervention. What is next step?
a. bilateral anterior nasal packings x 24 hours
b. return to OR for exploration
c. fluid resuscitation and refer to original surgeon
d. arrange for IR
d. arrange for IR
53
which is the most common source of venous bleeding during maxillary osteotomy at leFort I level?
a. Facial vein
b. pterygoid venous plexus,
c. laceration of pterygoid musculature
d. descending palatine vein
b. pterygoid plexus
- Arterial bleeding commonly from DPA, PSA, sphenopalatine ( all branchs of maxillary artery)
- check labs ( INR, PT, PTTS, platelets)
- Ant and posterior nasal packings
- consider IR
54
When is blood transfusion indicated?
| -2 indications
1. H/H - 8/30
2. Blood loss > 30% ~1500cc
risk of fevers with transfusion
55
Hemostatic measures? 5 options
1. LA with epi
2. Electrocautery
3. HOB elevated
4. Hypotensive anesthesia (MAP <70)
5. Hemodilution techniques = volume expansion with crystalloid.
Experimental = TXA and DDAVP (desmopressin) showed decrease blood loss compared to hypotensive anesthesia.
56
Best option for midface deficiency?
1. Modified lefort I
2. Quadrangular Lefort
3. Modified lefort III
4. alloplastic implants
4. alloplastic implants - malar and submalar implants
made of silicone or medpor
Beware of dishface deformity = advancement of a small maxilla without malar correction.
57
When performing a Lefort I in an ungrafted bilateral cleft lip and palate pt which should be avoided?
a. Autogenous bone grafting and rigid fixation
b. Osteotome seperation of the premaxilla from nasal septum and vomer
c. Advancement of the lateral segments for closure of cleft-dental gap
d. Circumvestibular incision and maxillary down fracture
D. Circumvestibular incision and maxillary down fracture
- key to cleft and orthognathics is stability and blood supply.
- requires high vestibular tunneling
58
The holdaway ratio is used to plan which procedure?
a. Maxillary osteotomy
b. Mandibular osteotomy
c. Complex 2-jaw surgery
d. Genioplasty
D. genioplasty
- Holdaway ratio = line from N to B, then you look at the ratio of L1 to NB and NB to pogoniun of chin point.
L1-NB:NB-Pog should be 1:1 ratio or within 3 mm if not requires genio
problem is that it relies on ortho setup.
Osteotomy must be 5mm below tooth apices and mental foramen
Must go forward at least 4mm to make a difference
59
Which muscle layer is reapproximated as a distinct layer during soft tissue closure following transoral genioplasty?
a. Genioglossus
b. Geniohyoid
C. Mentalis
d. Platysma
c. Mentalis - can lead to lower lip ptosis or witches chin if not resuspended
60
When performed at the same procedure, genioplasty and SSO:
a. increases risk of IAN paresthesia
b. decreased risk of paresthesia of IAN
c. has no effect on IAN paresthesia risk
d. should not be performed simultaneously
A. increased risk of paresthesia
Genio complications:
Paresthesia, lower lip ptosis, infection, alloplast defect due to resorption.
61
What is most stable orthognathic movement?
a. Mandibular advancement
b. Maxillary inferior repositioning.
c. Segmental maxillary expansion.
d. Maxillary superior repositioning
Most unstable?
D. Maxillary superior repositioning - if it relapses it relapses superiorly due to scarring
Segmental maxillary widening is least stable, then maxilla down is next least stable then mandibular setback
Stability is not as common with rigid fixation
62
Which 2-jaw procedure has the best long term stability?
a. maxilla up and mandibular back
b. maxilla forward and mandible forward
c. maxilla down and mandible back
d. maxilla widening with mandible back
Maxilla impaction and mandible forward is most stable.( but not listed)
a. second most stable is Maxillary advancement with mandibular setback.
63
relapse noted 2 years s/p SSO advancement is likely due to?
a. condylar malpositioning at sx
b. condylar resorption
c. ortho relapse
d. hardware failure
condylar resorption
64
3 weeks after VRO and release of MMF an 8mm open bite noted likely due to?
a. condylar sag at sx
b. ortho relapse
c. mvmt at osteotomy site
d. condylar resorption
Condylar sag at sx
condylar sag at surgery would mean condyles were " loose" in joint - after msucles tighten they pull the condyles up greatign an open bite.
65
Do you close open bites with mandible or maxilla?
Maxilla since CCW rotation of the mandible is resisted by suprahyoid muscles that pull mandible down and back.
- you can close small open bites with SSO (<3-4mm open bites)
66
LeFort incision placement?
Lefort Osteotomy placment?
5-7 mm above MGJ
5 mm superior to second molar root tips
67
BSSO bony irregularities and inferences are most likely found on the ?
-medial anterior portion of the proximal segment or the distal portion of the distal segment
68
BSSO relapses increase at what advancements?
>7mm
- must strip medial pterygoid muscle with j stripper especially for setback procedures.
69
Paresthesia rate of IAN in BSSO?
80 -100% immediately with 10-20% permanent.
70
Ratio of soft tissue to pogonion advancement is ?
.7mm : 1.1 mm
71
Most common complication of orthognathic surgery?
What is the incidence of neurosensory deficit one year after SSO?
Paresthesia of IAN ~32%, 3% severe paresthesia
Most serious complication is bleeding
12% had long term (>1 year) paresthesia - most studies say 15-20%
72
Antibiotics in orthognathic surgery:
a. are not indicated
b. should reduce the incidence of infection
c. Should be continued 1 week postop
d are msot effective when started 2 days prior to surgery
b. should reduce the incidence of infection
More complications in females, post op abx for at least 2 days had less infection.
73
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Nasal tip deviation following LeFort surgery is due to:
a. Overimpaction of maxilla
b. Underreduction of ANS
c. Overredictuion of pririform rims
D. Underreduction of nasal septum
```
D. Underreduction of nasal septum
Septal deviation repair with resection of caudal (inferior) septum, but can be prevented with suture of septum to ANS at time of surgery
74
Treatment of maxillary oronasal fistula following maxillary surgery?
Sinus management/conservative treatment initially - decongestant, nasal spray, abx
Splint coverage secondarily
Surgical last option for soft tissue flap repair.
75
What soft tissue changes can you expect with maxillary advancement? maxillary impaction?
Maxillary advancements changes soft tissue at a 50-80% rate or moving the maxilla forward 2mm with allow for 1-1.6mm more tooth show.
Maxillary impaction is closer to 1:1 ratio (~90%)
76
In a patient who has mandibular advancement, the ratio of soft tissue to hard tissue changes at pogonion are closets to?
a. 1:1
b. 1:2
c. 2:3
d. 1:4
a. 1:1 (80-90%)
genioplasty = 1:1 changes
Genioplasty will not affect lower lip.
77
What nasal changes occur after LeFort advancement and impaction?
a. increased NLA
b. decreased alar base width
c. Dorsal hump will be less noticeable
d. Nasal tip rotation is unaffected
C. Dorsal nasal hump is less noticeable since the nasal tip elevation and rotation and forward with advancement and impaction
- advancing maxilla = decreased NLA, lip thinning, alar base widening, and nasal tip changes, improved columenllar show
78
What is the best way to preserve vermillion border display following LeFort Osteotomy?
a. alar base cinch
b. v-y closure
c. incision at MGJ
d. reduction of ANS
b. v-y closure - prevents lip flattening or thinning
lower vestibular incision (5-7mm) allows for less lip thinning
Alar base cinch control alar base widening.
ANS reduction controls nasal tip on advancements and rotations.
79
Which maxillary movement results in worst alar base widening?
a. posterior repositioning
b. inferior repositioning
c. anterior repositioning
d. transverse expansion
c. anterior repositioning
alar base widening occurs in all movements but is worst in advancements
80
A complete inferior turbinectomy during a LeFort procedure may result in?
a. choanal atresia
b atrophic rhinitis
c rhinophyma
d. nasal dysplasia
b. Atrophic rhintis
turbinates warm and moistuize air
81
Which of the following occurs with LeFort impaction?
a. increased nasal volume, improved airflow
b. decreased nasal volume, improved airflow,
c. increased nasal volume, reduced airflow
d. decreased nasal volume and reduced airflow
b.. reduced volume and improved airflow (counter intuitive)
this is because you are opening the internal nasal valve (angle of upper lateral cartilages to septum increases with impaction) normal is 10-15 degrees, but in VME patients it is <10 degrees
presx Cottle test is used to test if impaction will aid in airflow.
82
When is it best to do adjunctive rhinoplasty for hump reduction?
6-9 months is best to see how soft tissue settles after maxillary surgery, but simultaneous is OK just avoid overreduction
83
Nasal tip ptosis occurs from?
Pollybeak deformity occurs from?
Maxilalry downgraft or ANS overreduction
Maxilary down graft or Overreduction of nasal septum
Consider cartilage strut graft for nasal tip support ( inbetween nasomaxillary crest to improve tip support in down grafting procedures)
84
Complications of Maxillary setback?
Nasal tip moves inferiorly. Less lip support ( NLA increases)
85
Mandibular advancement will affect?
Lip competence improves as mandibular incisor will support lower lip, not maxilalry incisor.
labiomental angle decreases
Improved chin prominence and neck chin thorat angle improves
Mandibular setback does the opposite - may cause iatrogenic obstructive sleep apnea
Again soft tissue to hard tissue moves 1:1 (~90%)
86
What is major resistance to expansion of maxilla?
All suture contribute ( not jsut the midpalatal suture) - Z-T, Z-F, Z-M, N-M
resistance increases with age
87
When to consider orthopedic expansion of maxilla?
Growing kids or palatal tipped teeth
Appliances include Hyrax (less skeletal expansion more dental tipping) and Haas - has acrylic flanges for greater skeletal advancement, but can cause palatal tissue impingement.
88
Regarding SARPE, which is true?
a. complete downfracture is required.
b. pterogomaxillary dysjunction is required
c. more expansion occurs anteriorly than posteriorly
d. indicated for expansion <6mm
C. More expansion occurs in anterior than posteiror.
Relapse greatest in canine region.
89
What are indications for SARPE?
a. Any discrepancy over age 18
b. Age over 18 with discrepancy >5mm
c. any age with 5mm discrepancy
d. Age under 18 with >5mm discrepancy
b. age over 18 discrepancy >5mm
(18 in men, 15 in girls)
SARPE is better than lefort is transverse constriction is in anterior (posterior is better for 2 piece)
90
What is negative space?
Is it increased or decreased in patient with transverse discrepancy?
Negative space is distance from commissure to buccal surface of teeth.
It is increased in transverse discrepancies.
91
23 yo has maxillary superior repositioning with midline split and transverse expansion of 9mm at molars. She returns one year later with anterior open bit. Why?
a. Poor condylar positioning
b. relapse of transverse widening of maxilla
c. idiopathic condylar resorption
d. hardware failure
b. relapse in transverse widening of molar causes increase posterior height and anterior open bite.
92
When looking at facial assymetries is an open bite or occlusal cant indicative of a slowly progressing pathologic process?
Slow progression leads to an occlusal cant because most cases occur in mandible (trauma/ankylosis, ICR, ICH, syndromic) and the maxilla follows the mandibular growth. Leading to both jaws having a cant.
Rapidly progressing diseases with show open bite or crossbite.
93
Before taking asymmetry cases to surgery you must know if growth is complete. What studies are used to identify active bone turnover?
Technetium 99m bone scan - identifies active bone turnover.
Gallium, indium, PET scans are also useful
94
Inverted L Osteotomy indication?
Best when you have an anterior open bite, but maxilla is already in good position so mandible only require CC rotation.
Consider in patioents with ICR or JRA
95
What is Gunson Artnett Protocol?
Used for condylar resorption cases.
presx for 3-6 months meds included NSAID, DOXYcycline, OMega 3 FAs, multivitamin, calcium, vitamin D, simvastatin, can consider TNF-alpha blocker called etanrecept
continue 6-12 months postsurgically with class II elastics to pull mandible forward and unload TMJ
96
Distraction Osteogenesis resposne of soft tissue is called...
Distraction Histogenesis - adaptive soft tissue changes that allow for maximal skeletal movement.
97
Phases of Distraction Osteogenesis?
Corticotomy and device application at time of surgery
Latency 5-7 days
- if too short can lead to nonunion if to long will not elongate due to fusion
Allows soft callus to form.
Distraction usually 1 mm qd (.5mm BId or .25 qid) until goal is reached
Stretches soft callus
Consolidation is 3 x distaction usually 2-3 months.
Allos hard callus to form
98
DO indications
Severe mandibular deficiency >8mm of over jet.
- Treacher colins, pierre Robin, TMJ ankylosis, OSAS
Severe maxillary AP deficiency (>5mm) = CLCP, Craniosynostosis (crouzon's, aperts)
Severe vertical ramus deficiency
Hemifacial microsomia
