First Semester Flashcards
List the 10 steps in order for a double jaw surgery.
1) Place K pin
2) Make initial cuts on mandible. Place gauze
3) Do cuts on maxilla, downdraft, place maxilla where its supposed to be using intermediate splint
4) Jawas held together with MMA
5) RIF maxilla
6) Finish mandible surgery
7) Use final splint to know where mandible is supposed to be
8) MMF again
9) Seat condyle
10) RIF mandible
Who fabricates the splint, the orthodontist or the surgeon?
Surgeon
When is a single splint used?
single jaw
When is are two splints used?
double jaw
What is an intermediate splint?
It is used to place maxilla where its supposed to be (surgical movement) during double jaw surgery while the mandible is in the exact same position as pre-surgery
What is a final splint?
In a double jaw surgery, it is placed on the maxilla after RIF to allow surgical positioning of the mandible
This splint is also often used as a rehabilitation splint
When should a deep bite be leveled?
post-surgery
When should an open bite be leveled?
pre-surgery (unless the maxilla has multiple planes, then the planes should be segmented and the leveling is completed during surgery)
List the 11 surgical-orthodontic treatments in the hierarchy of stability from most stable to least stable.
1) Maxilla up
2) mandible forward
3) chin, in any direction
4) maxilla forward
5) Maxilla, asymmetry
6) Mx up + Mn forward
7) Mx forward + Mn backward
8) Mandible, asymmetry
9) Mandible back
10) Maxilla down
11) Maxilla wider
What three surgical movements are considered “very stable” in the hierarchy of stability?
1) Maxilla up
2) Mandible forward
3) Chin, in any direction
What two surgical movements are considered “stable” in the hierarchy of stability?
4) maxilla forward
5) maxilla, asymmetry
What three surgical movements are considered “stable with RIF only” in the hierarchy of stability?
6) Mx up + Mn forward
7) Mx forward + Mn backward
8) Mandible, asymmetry
What three surgical movements are considered “problematic” in the hierarchy of stability?
9) Mandible back
10) Maxilla down
11) Maxilla wider
What is condylar sag and what will it result in after surgery?
When the condyle is not seated enough during surgery it will result in anterior open bite after surgery. (condyle will seat by itself after surgery)
What is condylar over-seating and what will it result in after surgery?
When the condyle is placed too forcefully posteriorly during surgery it will result in posterior open bite after surgery. (Condyle will move forward off of retrodiscal tissues after surgery)
List the four stages of distraction osteogenesis.
1) Osteotomy phase
2) Latency phase
3) Distraction phase
4) Consolidation phase
What occurs in the osteotomy phase of distraction osteogenesis?
The cuts are made
preservation of periosteum is critical
What occurs in the latency phase of distraction osteogenesis?
Inflammatory stage and initiation of healing occurs (introduction of inflammatory cells), occurs for 5-7 days. (do NOT distract during this period)
What occurs in the distraction phase of distraction osteogenesis?
The time to distract. A formation of a soft callus occurs.
Fibroblasts and mesnchymal stem cells are introduced.
What occurs in the consolidation phase of distraction osteogenesis?
Conversion from soft callus to hard callus. (remodels to lamellar (reg) bone)
Takes 120 days
Introduction of osteoblasts
During presurgical orthodontics it is important to make roots ____ where surgical cuts will be made
divergent
If the patient presents with open bite and two planes of occlusion, why should you not level with a continuous archwire?
You should use segmental arch wires instead to maintain the separate planes of occlusion, and the leveling should occur surgically. If you level with a continuous archwire, there is a high tendency for relapse.
In a genioplasty, what is the ratio of soft tissue movement to bone movement?
1:1
What is the difference between IVRO and BSSO?
IVRO includes a bone graft
What is the tooth bearing segment of the mandible?
The distal segment
What is distraction histogenesis?
Remodeling of the soft tissue. It just adapts from the hard tissue growth (it doesn’t grow)
Where are three donor sites you can obtain bone grafts?
Calvarium
Illiac crest
Ramus
When should you do a SARPE on an adult patient?
If they have severe crossbite more than 4mm per side (8mm total)
What are the two types of chin implants?
subperiosteal
supraperiosteal
Chin implants may cause resorption of lower incisors. Which type of chin implant typically results in less resorption?
Supra periosteal results in less resorption than subperiosteal
For patients with class 2 div 1 with long LAFH, ___ may be sufficient whereas for class 2 div 2 patients with true mandibular deficiency ____ may be indicated
Maxillary impaction only
Maxillary impaction plus mandibular advancement
With a steep mandibular plane and long face, the mentolabial sulcus will be ___
flat
A BSSO movement of ___-___mm is not worth it. Instead, camouflage and class 2 extraction pattern should be done.
3.5-4mm
What is tripod used for and which teeth are in contact?
Only for mandibular advancements (with short LAFH)
Contact on incisors and second molars only
True or false… mandible forward and backward is 1:1 ratio of hard tissue to soft tissue movement
False. Forward movement is 1:1 but backward movement is less because of saggy skin
Post-surgical orthodontics should be limited to ___months
6
Surgical cuts should be __-__mm away from root apices
3-5mm
If a patient had RIF from orthognathic surgery, the pt should expect to return to the orthodontist in __-__ weeks
2-3
When can a pregnant woman have orthognathic surgery?
4-6 months after delivery
What are three presurgical orthodontic goals?
Alignment (no rotations)
Establish desired vertical and AP incisor position (segment arch wires if necessary)
Arch compatibility
With a three piece maxillary surgery, the cuts are made distal of the ___. Therefore, the canine needs root ___ tip and the lateral needs root ___ tip. How do you obtain this?
lateral
distal
mesial
flip the left and right lateral brackets
*Conflicting information in study guides. 3 piece cuts can also be made between canines and first premolars. depends on surgeon’s preference?
When a patient returns from a transverse maxillary expansion surgery (the wires were initially segmented to produce surgical movements) a continuous archwire must be placed. However, ___ cannot hold the transverse, and ___ cannot yet be used. So what should be done?
NiTi
19x25SS
Use 045SS on auxiliary (or headgear) tubes to hold the transverse (can be passive or slightly active)
What are Iowa spaces?
Bolton space for tooth-size discrepancy, but also may be used for surgical cuts
With mandibular surgery, the ___ determine the face height
lower incisors
What is the class 2 extraction pattern for camouflage and surgery?
camouflage: U4s/L5s
Surgery: U5s/L4s (retract lower incisors to increase OJ in order to maximize surgical movement)
What is the recommended stabilizing arch wire in a 22 slot appliance?
21x25SS or TMA
What should occur during the first appointment post-surgery?
Repair broken stuff
Use 19x25TMA or 21x25NiTi to connect the maxillary segments (but it will not hold the transverse, so an auxiliary 045SS in headgear tubes should be used)
Use light vertical elastics for settling (primarily to override pt’s dental proprioception and prevent CR-CO shift) (elastics are in direction of surgical movement)
What occurs in the 2nd through 4th appointments post-surgery?
2nd: change AWs as needed. continue elastic wear
3rd: Teeth usually have settled into good occlusion. Elastics at night only. Go into heavy AW at this time as necessary
4th: Usually discontinue elastics at this time.
During a maxillary impaction (or advancement), how can the surgeon prevent the nose from looking larger?
Alar cinch - suture that goes around the alar bases to bring the nose close together
Or a V-Y cinch can be done (which also can be used to lengthen the upper lip)
True or false… there is an increase in nasal breathing when the maxilla is impacted and/or advanced
true
What is an anterior sub apical osteotomy?
Extract premolar and move the anterior segment back (used for mandible, protrusive maxilla, open bites, and excessive deep bites)
can cause lots of problems, devitalization, and necrosis of teeth.
What is a posterior subapical osteotomy (AKA ___)?
total sub apical osteotomy
Moves the whole dentoalveolus
When is a posterior sub apical osteotomy performed? what are some problems that occur when performed in the mandible?
When you like where the chin is but you have to move the teeth only.
Useful in bimax protrusive cases when A and B point are good but have dental alveolar protrusion.
unilateral crossbite
excessive eruption of posterior teeth
Can cause IAN problems
What is the maximum movement with mandibular surgery?
10mm
With a sagittal split osteotomy, the ___ muscle is released, then a saw is placed in ___mm, then a chisel is used to perform the split. A ___ can be used to put the bones together but still allows some play
medial pterygoid
3mm
Lag screw
What is an IVRO?
Intraoral vertical ramus osteotomy
It is a condylotomy that will separate the condyle from the rest. Therefore, this shouldn’t be done for advancements because you’d need a bone graft
What is a body osteotomy?
narrow the mandibular dental arch by removing part of the anterior mandible
With a genioplasty or inferior border osteotomy, an incision is made ___ from ___ to ___. What is a “complication” of this procedure?
inside lower lip from mental foramen to mental foramen
lips are repositioned and can take 3-6 months to return to normal
When should a double jaw surgery be performed?
The maxilla should be placed at the correct position for maximum esthetics of incisor teeth and lip support. Fit the mandible to maxilla, if it doesn’t fit, 2 jaw surgery.
If there is a 7mm or more discrepancy, 2 jaw surgery is indicated
Glabella and ___ should be coincident. If after surgery they are not perhaps a ___ is needed.
ST pogonion
genioplasty
What are the 9 steps for Cast surgery?
1) mount maxillary cast on articulator w facebow
2) Mandibular cast mounted with CR bite
3) Model simulation of anticipated movements (AP, vertical, and mediolateral with Erickson table)
4) Maxillary cast cut away from mounting ring
5) Remount maxillary cast in desired position
6) Compare to the ceph prediction
7) This is the predicted result of 1st stage of surgery (make intermediate splint for this mounting. Intermediate splint goes on mandible and closes into maxilla. check vertical, then fixate)
8) Remount mandibular cast in desired position
9) Make second split for this new mounting (splint on maxilla and close mandible into it)
What are the two main reasons for doing cast prediction?
1) make sure the movement of the dental casts is what you want it to be
2) generates occlusal splints for use at surgery
How do you make a surgical splint? (5 steps)
1) apply separating medium to teeth
2) Place quick curing acrylic on occlusal surface (one arch) and close articulator
3) Minimize porosity by curing acrylic in pressure cooker
4) Trim and polish cured splint
5) If RIF is going to be completed, the final splint is relieved so only indentations for mandibular cusps remain
What are the differences between splints used for RIF or MMF?
RIF: thin and uniform thickness
MMF: Thicker and greater separation of posterior than anterior teeth
What is the Erickson table?
special base that rotates, measure distance to molar, premolar, incisor
gives us vertical measurements of R and L
Describe the sequence of double jaw surgery (11 steps)
1) soft tissue incisions and partial osteotomy in mandible without splitting
2) soft tissue incision and osteotomies of maxilla
3) maxillary downfracture
4) maxillary segmentalization
5) MMF of mandible and segmented maxilla into intermediate splint
6) RIF of maxilla-mandibular complex into final cranial base (maxillary position)
7) removal of MMF to free the intermediate splint
8) completion of BSSO and MMF of mandibular distal segment into final splint
9) seating of condyles and RIF between distal and proximal segments
10) closing of soft tissue on the mandibular procedure
11) closing of soft tissue with a V-Y closure or alar cinch if necessary
What is the surgical vertical reference?
K pin
What is the surgical transverse reference?
splint
if not splint, then its the mandible
What is the surgical AP reference?
splint
What is the distal segment and what is the proximal segment?
distal segment = teeth
proximal segment = condyle
place distal segment into final splint, then MMF. Then seat proximal segment, then RIF
What is the advantage of distraction osteogenesis?
when advancements are greater than 10mm there is a lot of relapse from ST. If you advance slowly, it give the tissue time to adapt and you see less relapse.
Distraction osteogenesis = bone formation induced by gradual separation of bony segments “lengthening” hard tissue.
(Distraction histogenesis = remodeling of the soft tissue. tissue doesn’t lengthen like the hard tissue, it just adapts)
True or false… even after distraction osteogenesis, patients still often need surgery to get the occlusion right
true. therefore, DO is not good for the majority of patients but is good for craniofacial anomalies
Describe the two categories of distraction
Physeal distraction = endochondral bones (limbs)
Callotasis = distraction of a healing callus between bone (what is done with our patients)
What is the law of tension stress?
steady tension on bony fragments lengthens the bone by a healing callus
What are the indications for Distraction Osteogenesis?
Severe deficiency of jaws requiring more than 10-15mm lengthening
Short mandibular ramus
Widening narrow adult maxilla anteriorly
widening narrow V-shaped mandible
What are the advantages and disadvantages of an inferior border osteotomy?
advantages: Mentalis muscles remains attached so 1:1 ratio of ST to HT. no relapse
disadvantages: mental nerve damage. notching when more than 5mm
The philtrum should be ____ to the height of the commissures
equal
It is not ideal if the hyoid bone is positioned inferior to ___
C4
Mandibular advancement changes hyoid bone and helps contour “double chin”. in contrast, mandibular setback = downward hyoid position and = unfavorable neck-chin contour
In a case of mandibular deficiency with short LAFH, a double jaw surgery is performed and the maxilla goes ___. the mandible is moved [first/second].
counterclockwise.
first
What are the two ways to level the CoS in surgical patients?
1) intrude incisors (done pre-surgically, helps with AP movement)
2) Extrude premolars (do POST-surgery. Tripod these patients for surgery, done with pts with short LAFH, brachy)
If during surgery the condyle isn’t seated enough it could lead to ___ after surgery. If it is __-__mm surgery may be needed again
open bite
3-4mm
The splint can be removed after ___ weeks if RIF was used and ___ weeks if MMF was used
3-4
6
Mandibular third molars need to be extracted ___ months [before/after] BSSO
6 months
before
___ of the population have facial asymmetries. 75% are in the ___ face. Deviation is most commonly to the ___.
1/3
lower
left
What are the two most common causes for facial asymmetries?
Hemifacial microsomia
condylar fracture (asymmetrical growth)
If there has been a condylar fracture, the jaw should be immobilized for __-__ days.
7-14
Describe grade 1 hemifacial microsomia
mild asymmetry = can be managed orthodontically with functional appliances
Describe grade 2 hemifacial microsomia
condyle or ramus are small, can be managed orthodontically with functional appliances
Describe grade 3 hemifacial microsomia
Complete absence of condyle and ramus, soft tissue is very deficient. need to do surgery (early surgery to lengthen the ramus , make new condyle, DO
What are there three stages for surgical correction of grade 3 hemifacial microsomia?
1) Tissue augmentation (age 5-8), DO if needed
2) Jaw relationships (age 12-15, ortho surgery as needed. genioplasty helps lip function and esthetics
3) Contour modifications - enhance anything that is still weird. Ear, skin, etch.
___ is the their major cause of asymmetric deficiency in a child
Juvenile rheumatoid arthritis
True or false… you should use functional appliances with children with juvenile rheumatoid arthritis
false… more force on the joint can degenerate it
What type of surgical intervention should be done with children with juvenile rheumatoid arthritis?
avoid mandible lengthening (it could affect the TMJ). Try maxillary surgery or genioplasty instead
Relapse is likely if ramus continues to shorten
What are the surgical options for Hemimandibular hypertrophy (condylar hyperplasia)?
1) excision of bone at head of condyle followed by recontouring
2) Removing the condyle/condylar process
The maxilla is often canted due to asymmetry in mandible. You should ___ the maxilla instead of ___. Also, the nose almost always will be off, so ___ should always be discussed.
impact
downgraft
rhinoplasty
ST glabella to subnasale and subnasale to mention should be a ratio of ___
1:1
Incisors should be in correct position relative to the ___ (not ___) so patients look good after surgery.
palatal plane
cranial base
compatible arches should be no more than ___cusp off
1/2
HDEZ is ok with 1/2 cusp off on 2nd molars but first molars should be perfect
If you need 10mm of maxillary expansion, should you do a SARPE or lefort?
SARPE, then 1 piece maxillary surgery later
Class 3 elastics ___ the maxillary arch so you should put ___ in the archwire to avoid this or you could…
constrict
expansion
run class 3 crossbite elastics (inside of upper molars to buccal of lower canines)
The tongue follows the [maxilla/mandible]
mandible
True or false… the bite force post-surgery is easily predicted
false. cannot predict the effects because there are variable effects on bite force
True or false… there is little change in tongue/lip pressure post surgery
true
True or false… TMJ problems are more rare with RIF than MMF
true
You are more likely to see condylar changes in mandibular [adancements/set-backs]
advancements
____ is the most unstable surgical movement, therefore you should overcorrect by ___. __ can make this more stable.
Widening of the maxilla
2mm per side
SARPE
True or false… camouflage is not a good idea with patients who have a steep, long face, with open bite
true
Which races tend to have more root resorption? what characteristics of roots tend to have a higher chance of root resorption?
Hispanic > White > Asian
Dilacerations, slender, pointed roots
Cases wish camouflage have increased risk of root resorption due to roots hitting cortical plate and longer treatment durations and long span to move teeth
What is nonunion?
fibrous tissue where bone should be (between osteotomy cuts)
What is malunion?
bone healed but not where the segments were supposed to be
Condylar resorption is higher risk in __, __, and in ___
high angle
class 2
females
The rule of thumb is that __mm vertical difference between maxillary incisors and premolars should be treated as a multisegment osteotomy
> 2mm
Class 2 patients are typically transverse deficient. If the canines are too narrow, a ___ is indicated. if a posterior crossbite is present, a ___ is indicated
2-piece
3-piece
When do we consider SARPE?
severe transverse problem (>8mm total)
Is post-op condylar resorption more common in males or females?
females (it has a hormonal influence)
Does post-op condylar resorption occur more frequently in MMF or RIF? What type of pt presentation is at risk of post-op condylar resorption?
MMF > RIF
High angle, class 2, requiring double jaw surgery
Obstructive sleep apnea episode is __s of no breathing, and ___% reduction in airflow
10s
50%
What is the gold standard to diagnose obstructive sleep apnea?
overnight polysomnography
What patient population is at a higher risk of OSA?
overweight, middle aged men
What are some treatment options for OSA?
muscle training/positioning
sleeping different
weight loss
quit alcohol
CPAP
Surgery
A mandibular anterior positioning appliance (Vanderbilt appliance) will result in protrusion __-__ of maximum protrusion
1/2 - 1/3
What are some surgical options to treat OSA?
tracehostomy - almost never done
MMA - pulls tissues of palate forward and increases tongue support. Advances both jaws (more in mandible of class 2s.)
UPPP - Soft palate is shorter but thicker (when this fails go to MMA)
Which is better tolerated by patients, MMA or UPPP?
MMA
What are the advantages of MMA?
permanent airway enlargement
great breathing improvement
profile improvement (social benefits)
What are the methods to treat OSA in order? If the first option doesn’t work, go to second, if second doesn’t work, go to third.
1) lose weight, quit alcohol, improve sleep habits
2) CPAP
3) MMA
When do we do a 3-piece?
When do we do a 2-piece?
2 planes of occlusion
transverse problem
In surgery, what is used to find the correct transverse and AP position?
In surgery, what is used to find the correct vertical position?
Splint
K pin
What are your options for maintaining transverse dimension post-surgery?
1) 045SS through headgear tubes (ligated between 8 and 9)
2) Splint
For patients that are asymmetric in the mandible, what procedure might be the best?
IVRO or TVRO
For what patients might you do an extra oral vertical ramus osteotomy?
patients with craniofacial abnormalities (hemifacial macrosomia)
Avoid on patients that are prone to keloids (African Americans)
When do you do a combined vertical and sagittal ramus?
when a mandibular advancement of 10-15mm is needed
Pre-surgery, how do you measure the vertical dimension?
Erickson table
What articulator does Hernandez use?
Galleti articulator
What type of rotation do you get if you move the maxilla first vs mandible first?
maxilla first = clockwise rotation?
mandible first = counterclockwise rotation
*not sure about this one, go back and look at slides
For what type of patients would you usually do the mandible first?
short face, needs more chin projection
In most facial asymmetries, the chin deviates to which side?
left
What is the most frequent growth problem due to trauma?
condylar fracture
Which jaw do you treat first in a long face patient?
Maxilla (clockwise (posterior up to allow forward rotation and mandible))
In which types of patients do you level before surgery?
class 2 div 1 - long face - intrude lower incisors with segmental mechanics so you can get more autorotation of the jaw
How do you determine whether to impact the maxilla or advance the mandible in a class 2 div 1?
Based on incisor display and tooth-lip ratio.
If incisor display is good, impact posterior only. If incisor display is excessive impact anterior too.
How much space do you want in between root apices before surgery?
minimum of 3-4mm is needed, so shoot for 5-6mm
what type of mandibular surgery is common for setbacks but requires a bone graft?
IVRO and TVRO
How do you know if there is a transverse deficiency pre-surgery?
hold the models in class 1 and evaluate
Any time you are correcting an open bite, what type of maxillary surgery should you be doing?
3-piece because there are two planes of occlusion (AKA a vertical problem)
When is an Iowa space used?
when there is a Bolton discrepancy
What is the procedure that is used to close an anterior open bite, to depress an elevated anterior dentoalvelar segment?
anterior sub apical osteotomy (also used to correct bimax protrusion)
In order to maintain blood supply in a lefort 1, what must remain?
soft tissue pedicle
Don’t inject the palate with epi, otherwise it will limit blood flow
What are the three ways to reduce blood loss in a Lefort 1?
use vasoconstrictor in anesthetic (except in palate)
Elevate head of operating table 15 degrees
Modify hypotension anesthesia to control systolic BP
What are the vessels that are at risk for hemmorage in a lefort 1?
descending palatine neurovascular bundle
How long does facial edema last? when does it peak?
2-3 weeks
peaks at 2-3 days
How soon after surgery must a pano be taken?
day after surgery
What procedure is used for correction of isolated unilateral posterior crossbite?
posterior subapical osteotomy
What medications are given to help control edema and infection?
corticosteroids (1-2 days)
antibiotics
What are the four steps of splint fabrication?
1) lay a roll of uncured acrylic on mandibular teeth
2) close the articulator so the maxillary teeth are occluding
3) allow acrylic to cure and trim excess
4) place holes with bur in labial and buccal for attaching the splint to the AW
What are the advantages and disadvantages of RIF?
Advantages: increased comfort, stability, control of segments, facial edema decreases faster, increased safety, able to evaluate occlusion in OR, faster rehabilitation of muscles and TMJ, rapid bony healing
Disadvantages: technique sensitive, can get infections, increased cost, possible need for plate removal, devitalization of teeth
What are the general guidelines for vertical opening goals after RIF?
20mm at 2 weeks
30mm at 4 weeks
40mm at 8 weeks
What are the three factors that affect post op rehabilitation?
1) pts age
2) Stability of segments
3) type of surgery
What are the common problems encountered when doing pre-surgery check?
Incompatible canine widths
Interferences from 7s (band lower 7s, not uppers)
Not enough space for osteotomies (aim for 4-5mm)
After surgery, what elastics are used?
Full time 1/8 inch 3.5oz box elastics
What is nonunion?
mobile interface stabilized largely by fibrous CT
Does malunion always need corrective surgery?
No. The need for second surgery depends on esthetic and functional effect
What are three methods to decompensated for class 2 prior to surgery?
Run class 3 elastics
Extract Mn premolars
Open coils distal to max laterals to flare upper incisors
What are the positive and negative components of RIF?
Positive: rigid and stable
Negative: decrease plasticity and elasticity
What is a con to MMF?
less rigidity, pt’s can’t open and function for an extended period of time
What is considered the least stable orthognathic surgical procedure? How much relapse occurs in one year?
Transverse expansion
50% relapse in 1 year
What procedure is indicated for maxillary down fracture and correction of vertical maxillary deficiency?
Leforte 1 osteotomy
Name three approaches to improve vertical stability (for maxillary down fracture)
1) placement of heavy fixation bars from zygomatic arch
2) Interpositional placement of synthetic HA graft to improve mechanical stability
3) Use of simultaneous ramus osteotomy to minimize stretching of elevator muscles
What is the most common adjunctive esthetic procedure?
Genioplasty
What are the two main disadvantage of a sliding genioplasty (inferior border osteotomy)?
notching if more than 5mm of movement
mental nerve damage
What is the main disadvantage of chin implants?
resorption of anterior cortical plate
What are three advantages of BSSO for mandibular advancement?
overlap of bony segments increases stability
minimal change in muscles and TMJ
Great flexibility in moving the tooth bearing segment
What are three indications for open rhinoplasty?
secondary revision of cleft-lip nose
crooked or asymmetrical nose
revison rhinoplasty
difficult nasal tip
What procedure is used to correct a short philtrum?
V-Y cheiloplasty
What is the surgical technique in which new bone formation is induced by gradual separation of bony segments after osteotomy?
distraction osteogenesis
Who invented the DO procedure?
Illizarov
What is the predominant method of distraction in maxillofacial distraction?
Callotasis
What happens if distraction is done too early after osteotomy cuts?
decreased bone formation and decreased mechanical strength of new bone
What happens if you wait too long to distract after osteotomy cuts?
device may not be able to separate the bone
What is the primary indication for mandibular lengthening in infants?
to relieve respiratory obstruction and sleep apnea related to severe mandibular deficiency
What is the main indication for mandibular lengthening in preadolescents?
severe hypoplasia
What is the main indication for lengthening a hypo plastic maxilla?
craniofacial anomalies: crouton and apert
severe maxillary deficiency secondary to cleft repair
Explain the process of correcting a class 3 malocclusion due to maxillary retrognathism during mixed dentition
Target the maxilla
Perhaps expansion to “loosen the sutures” while using reverse pull facemask to encourage down and forward growth of maxilla.
Do at early age (8-10 years old)
Reverse pull facemask also will cause down and back rotation of mandible also correcting the class 3 molar
Explain the concept of the Pterygoid response
When the patients lateral pterygoids contract and give a false impression of the patients true bite.
Initially seen when pts are treated with Herbst
Explain the concept of a “tripod” position of the mandible after surgical advancement.
The tripod is a way to set the mandibular arch for surgery, causing anterior contact in incisors and L7s touching maxillary teeth in posterior.
Used for brachy pts with deep bite that you want to level after surgery. Level after surgery because the musculature will fight you prior to surgery. And, you want to increase the LAFH which can be done post-surgery by extruding the lower buccal segments.
Tripod provides the surgeon a stable enough position to occlude into the splint
How long should a patient wear Hawley retainers full time after a transverse surgical movement?
6 months
Why is a bone graft needed for cleft lip/palate patients? What is the orthodontist’s role?
to provide bone for the canine to erupt through
Orthodontist needs to expand and create space for the bone graft
Which has more bleeding, maxillary or mandibular surgeries?
maxillary
Why should you band the lower 7s but not the U7s until after surgery?
Banding the upper 7s can create interferences
What can happen to the soft tissue if too much bony chin is removed?
you could get dimpling of the soft tissue
How much expansion should be performed per day with SARPE?
0.5 - 1mm per day
Where should the spaces be provided for cuts in a 3 piece maxillary surgery? how do you obtain these spaces?
between U3s and U4s
swap L and R canine brackets for mesial root tip
True or false… methotrexate is used to treat juvenile rheumatoid arthritis
true
True or false… draining into sinuses and runny nose is an uncommon complication that requires treatment immediately
false
What is the difference between rate and rhythm in DO?
Rate = mm amount
Rhythm # of times per day
What is the difference between open and closed rhinoplasty procedures?
open = used for revision. get scars
Closed = blind procedure. no scars
What age is often considered appropriate to surgically treat maxillary retrognathism in males and females?
Males = 18
Females = 16
What age is often considered appropriate to surgically treat mandibular proghanthism in males and females?
Males = 21
Females = 18
How should you position a patient in a cephalostat who has asymmetry?
only place one ear-rod in
True or false… patients are often prescribed antibiotics prior to surgery and after surgery
true
What two types of drugs used to treat systemic diseases can inhibit orthodontic tooth movement?
1) corticosteroids and NSAIDs (interfere with prostaglandin synthesis) (especially indomethacin)
2) Osteoclast inhibitors for osteoporosis (Bisphosphonates)
Dilantin (anti-seizure) can cause gingival hyperplasia which may also slow tooth movement. Other drugs that dry the mouth may increase mucosal irritation to the appliances
true or false.. as a general rule it is better to maintain an existing crown even if it will be replaced later on
true
but if the crown is over-contoured it may prevent proper positioning of the tooth
True or false… the fact that a periodontally compromised tooth will eventually need to be removed means it should be removed before orthognathic surgery
false. retaining periodontally involved teeth is preferred over employing a temporary RPD to establish occlusion at the time of surgery.
gingival grafts should be performed BEFORE the surgery though
True or false… patients with a chin deficiency tend to have facially tipped lower incisors and therefor have a reduced gingival attachment
true.
before the chin is repositioned surgically, a gingival graft should be performed
With continuous arch wires, leveling occurs almost entirely by…
extrusion of premolars
this should be done post-surgically
If intrusion of incisors is to be carried out, the arch should be segmented and an intrusion arch should be used.
As a general rule, in preparing for mandibular advancement, retract the lower incisors ___mm further than their desired final position. why?
1mm
because the teeth will tip forward later on (relapse)
in contrast, over treatment of class 3 should be minimal. (lower incisors should be slightly prominent and the upper incisors should be slightly over-retracted)
As a general rule, orthodontic expansion should be limited to __ per side (___ total). that is, not more than a half-cusp crossbite correction
2-3mm
4-5mm total
What records are needed once presurgical orthodontics is complete?
pano and ceph (or CBCT)
dental casts
intraoral and extraoral photos
(if LeFort 1 osteotomy or if the mandibular dental arch will be segmented, you must have a face bow transfer
when is the ideal time to take records before the tentative surgery date?
2 weeks
after final AW has been in place for at least 3 weeks and is passive
Why are soldered brass spurs better than crimpable hooks for effective stabilization in surgery?
crimpable hoks can distort archwire,, break off, or slip in operating room
How thick should the splint be?
1-2mm producing the least tooth separation as possible in surgery
thicker the splint the more possibility for error as the mandible rotates into occlusion after the splint is removed
Following discharge form the hospital, most patients are able to return to limited activity within ___ weeks post surgery. Some are able to be back to work within ___
2
1 week
Although most facial edema is gone within 2-3 weeks after surgery, the jaw may not be healed enough for heavy mastication until ___ weeks. full bony remodeling take ___ months or longer
6-8
6
Maxillary expansion from surgery is unstable for approximately ___
6 months
heavy labial auxiliary wire should be used during this time
True or false… for surgery patients, It is good to use elastics for final settling of the occlusion (with posterior segments of wires removed for a few days) and then going directly to retainers.
true
true or false… almost all patient experience depression for a period following surgery.
true. can begin as early as 2nd day post-op
typically resolves with return to normal activity level. if prolonged, may require referral for counseling
Pts who will have a LeFort surgery can lose a lot of blood. What can be done preoperatively to manage this outcome?
pre-depositing one unit of blood
EPO (erythropoietin) administration 7-10 days prior to surgery
Bone and soft tissue will heal correctly if sufficient ___ is left attached to mobilized bone at the time of osteotomy
soft tissue pedicle
High-dose corticosteroids can help minimize surgical edema. ideally they should be administered when?
8-12 hours before surgery
additional doses after surgery are not required
List 10 advantages of RIF
1) improved comfort and convenience
2) Increased safety in immediate post-op period
3) more rapid bony healing
4) Evaluation of post-op occlusion in operating room
5) ability to stabilize bony segments that would otherwise be difficult to control
6) improved control of bony segments
7) increased stability
8) greater staging flexibility
9) faster reduction of post-op edema
10) rehabilitation of muscles and TMJ
List 7 disadvantages of RIF
1) technical difficulties
2) increased cost
3) increased risk of infection
4) possible need for plate removal
5) neurosensory disturbances
6) tooth deviatlization
7) post-op TMJ symptoms
What is the post-surgery infection rate?
2% following maxillary surgery
9% for RIF in mandible ( only 3% in mandible with MMF)
In a saggital split osteotomy, the horizontal osteotomy should extend ___ of the AP dimension of the ramus
1/2 - 2/3
Mandibular advancement requires the release of which muscle(s)?
Medial pterygoid
Mandibular set back requires the release of which muscle(s)?
Medial pterygoid and masseter muscle
When should lag screws or position screws be used in RIF?
Lag screws are used when there is good bony contact between the segments with the condyles in proper position
Position screws are used when bony contact between two segments is minimal
Small bone plates can fix the proximal and distal segments in a SSO. What would happen if the plate is not adapted exactly to the bone contour when the screws are tightened?
condylar displacement
What is an inferior border osteotomy in the body portion of the mandible most commonly used for?
to shorten the vertical dimension on one side (correct conditions such as hemimandibular hyperplasia)
What is an anterior subapical osteotomy commonly used for? (3 things)
1) close anterior open bite
2) depress an elevated anterior dentoalveolar segment
3) retrude or advance a dentoalveoalr segment
What are the four histological stages of bone repair?
1) inflammatory phase
2) soft callus formation
3) conversion to a hard callus
4) bony remodeling
Preserving the ___ is critical to formation of a healthy callus in DO and continued blood supply in long bones. therefore an [intraoral/extraoral] approach is more desirable
periosteum
extraoral
No clinical studies show that DO increases ___ volume, therefore pt may still require augmentation following DO
soft tissue
What are two disadvantages of alloplastic chin implants?
could resorb anterior cortical plate of them mandible
implant is placed between anterior mandible and mentalist, leading to attachment loss and a potential chin droop
describe the closed rhinoplasty technique
intranasal approach through an incision in the septal mucosa or rims of the nares
no external incisions are made
How does maxillary advancement change the nose?
tip of nose becomes more projected
dorsum becomes less prominent (may require augmentation
How does maxillary setback change the nose?
tip of nose becomes less projected
Dorsum becomes more prominent
Describe the differences in appearances of mandibular deficiency with normal or long LAFH to mandibular deficiency with short LAFH
long LAFH:
deficiency appears equally at lower lip and chin (or chin could be more deficient). tendency for accentuated mentolabial fold (but to a lesser degree. Elevator muscles not as developed. genial angle appears normal (or obtuse) CC is usually lack of chin and protruding Mx incisors.
Short LAFH: Well developed chin button. deficiency appears more at lip than chin. accentuated mentolabial fold. Brachy. CC is usually lip contours and lack of prominence of dentition.
In camouflage treatment, retraction of upper incisors is limited to ___mm. Lower incisors cannot be moved labially more than ___mm.
6mm
2mm
Surgically, it is much more difficult to permanently increase anterior face height by rotating mandible at condyles than within the ramus via osteotomy. why?
At the condyles requires lengthening of the elevator muscles
Ramus surgery allows the muscles to actually shorten
True or false… hemifacial microsomia is highly variable in expression and unpredictable in response to growth modification
true
Describe the management for an adolescent with asymmetric mandibular deficiency following condylar fracture
Functional appliance until growth is complete
then corrective surgery as needed
Describe the management for hemimandibular hypertrophy
can be an indication for early surgical intervention (if needed, remove the head of the condyle)
What happens to the maxillary posterior teeth and the mandible as face height increases and the maxillary palatal plane rotates down posteriorly?
maxillary posterior teeth move down
mandible tends to rotate down and back
In generally, excessive vertical height makes AP mandibular deficiency [worse/better] and proghtathsim [worse/better]
worse
better
As the mandible rotates down and back, the incisors become more ___ and more ___. It will also lead to separation of the incisors vertically leading to open bite tendency. However ___ can occur when incisors erupt enough to compensate. Even in patients with anterior open bite, ___ has likely occurred.
upright
crowded
deep bite or normal bite
over-eruption
A combination of what three things are the most diagnostic characteristics for long-face condition?
increased MPA
increased total anterior face height
decrease ratio of UFH:LFH
What are three ways to decrease fat height via surgical-orthodontic treatment?
1) Superior repositioning of the maxilla - total or segmental maxillary osteotomy (causes autorotation of mandible. careful not to impact anterior maxilla too much or it can compromise esthetics)
2) Bring lower jaw forward and upward (ramus osteotomy) (often does as secondary surgery after repositioning of maxilla if AP correction by autorotation on mandible is not sufficient)
3) Superior repositioning of the chin (mandibular border osteotomy (AKA genioplasty) Useful adjunct but unlikely adequate by itself
Should long-face patients have the CoS leveled before or after surgery?
before. it helps control vertical post-surgery (if done after surgery it will increase LAFH, this is why you with brachy patients you level after surgery)
If the gingival attachment is questionable, how soon should the gingival graft be performed prior to surgery?
2-3 months. However it is best if it done before ortho treatment started
How much incisal display do you want at rest after maxillary impaction?
30-40%
The surgeon uses an external mark (K-pin) and marks on the ___ after soft tissue reflection to make movements as close as possible to the surgical plan
maxillary bone
With RIF, any malposition can be noticed immediately and corrected. If the mandible does not occlude into the splint after the maxillomandibular wires are removed (usually due to premature contact of ___), then what happens?
molars
the screws are removed and bony interferences are located and corrected, then screws are placed again
With MMF, it may take ___ for malposition of the jaws to become apparent. If it is a small enough discrepancy, you could correct with ___, but if it is a large enough discrepancy you have to correct with ___
several weeks
elastics
surgical revision
Why are posterior maxillary movements difficult?
bone must be removed in the tuberosity area and the palatine bone (bone is dense, limited access)
When doing a segmented maxillary surgery, are the segments made before or after down fracture?
after
With a two segment maxilla surgery, the cuts are placed ___. It can allows expansion of ___mm in the molar region without compromising the blood supply of the palate
through the midline between the central incisors
5-8mm
In a 3 segmented maxillary surgery, __mm of space between the roots are needed for the cuts. The cuts are either mesial or distal to the canines depending on ___
3-4mm
where the step in occlusion begins
____ is key to the success of orthognathic surgery. in the short term, ___ adapts to form. In the longer term, ___ is affected by function, especially if active growth is occurring
physiologic adaptation
function
form
Patients orient their heads differently before and after surgery. If the head tips upward after surgery _______. If head tips downward post surgery ____
SN to true vertical angle will decrease
SN to true vertical angle will increase
Tendency toward head extension only occurs after ___ surgery
mandibular setback
with other surgical procedures, pts tend to flex the head so that the chin goes down
The tongue is attached to the mandible. As the mandible moves posteriorly, the tongue moves ____
down (not posteriorly)
Therefore, the greater the mandibular setback, the more downward movement of the floor of the mouth, which can create a “double chin”
How does tongue posture change when the mandible is advanced or the maxilla is repositioned?
It positions in a way that the relationship to the anterior teeth remains the same
(this is why a partial glossectomy isn’t effective, the pt will reposition their tongue anyways)
True or false… most patients can move air through their nose better post-surgically (maxillary impaction) than they could before
true
___, for most people, is the limiting factor in nasal airflow
the nostril
narrow nostrils are corrected with maxillary impaction surgery by widening alar base
TMD can arise as a result of surgical-orthodontic treatment in what 4 different scenarios?
1) by chance (independent of treatment) (could be due to emotional stress invoked from surgery)
2) Due to orthodontic treatment where a gross interference was introduced
3) Due to surgical correction (prolonged immobilization or final condylar position)
4) Final occlusal result, causing a lateral shift, occlusal interference, or anteriorly locked, occlusion
Improper RIF can increase ___, placing the condyle in a more ___ position in the fossa, potentially leading to TMD. How can this be prevented?
intercondylar width
lateral
recontoruing distal segment to allow passive positioning of the proximal segment
True or false… there is no way to predict how bite force will change, and the changes seem to be due to physiologic adaptations, tater than geometric changes
true
True or false… overall there is a large degree of tongue and lip adaptation after surgery, which can contribute to incisor stability
true
Neurosensory alterations, particularly of the maxillary and inferior alveolar nerves, are a predictable outcome of orthognathic surgery. Recovery of sensation occurs over ___ for many patients. beyond that time, some additional recovery is possible but not predictable
1 year
True or false.. the upper lip tends to recover sensation more quickly than mandibular regions
true
True or false… orthodontic or surgical treatment of facial growth problems has a drastic impact on subsequent growth
false.
it has little or no effect on subsequent growth of the face, although it may affect the growth of the treated area
True or false… post-treatment growth is a less important cause of instability after treatment than relapse
false. growth is more important
In which two circumstances is early surgery indicated?
1) extremely severe conditions that significantly affect the quality of life at an early age
2) Progressive deformity in which the condition steadily worsens because the affected area grows less than the adjacent normal areas (mandibular ankylosis)
Mandibular advancement is very stable in patients with short or normal face height and less than __mm advancement
10mm
Advancement of the maxilla is stable if not advanced more than ___mm. 80% of patients have less than __mm chance
8mm
2mm
Three procedures fall into the problematic (stability) category, defined as up to 50% of patients have __mm post surgical change and a significant percentage having over __mm change. what are these problematic procedures? Note though that even with these problematic procedures, at least half of the patient experience essentially no post-surgical change
2-4mm
> 4mm
Mandibular setback
Maxilla down
Maxilla expansion
True or false… with RIF the relapse of the mandible during the first 6 weeks is almost totally eliminated
true
In general, class _ surgical patients are less stable during the first year, cut show fewer changes beyond that
3 (compared to 2)
___ of patients who have surgery to correct a skeletal class 3 problem have a combination of maxillary advancement and mandibular setback
2/3
Retracting lower incisors in a class 3 case will [increase/decrease] chin prominence
increase
Surgical camouflage with onlay grafts is an alternative to Lefort surgeries. It is indicated for ___ deficiency and can be an isolated procedure, but likely done in conjunction with orthognathic surgery
midface
what are two soft tissue procedures that are helpful for severe class 3 patients?
1) submental lipectomy with platysma muscle plication (reduces excess tissue folds in the neck to compensate for effects of Mn setback)
2) Reduction cheiloplasty (eliminates excessive bulk of the lower lip that sometimes persists in patient who had a severe jaw discrepancy)
True or false… maxillary surgery is more esthetic and more stable than isolated mandibular procedures
true
What are three special considerations for orthodontic preparation for surgery?
1) ext of U4s is often needed
2) ext rarely indicated in mandible (if severe crowding, ext L5s)
3) If no posterior crossbite exists presurgically, one will exist post-sx. (because moving mx forward becomes wider relative to Mn)
In a mandibular setback, if the ramus is pushed back while trying to seat the condyles in the fossa then fixated, what will happen?
the ramus will come forward again when function resumes
Which is better for mandibular setback, BSSO or IVRO?
BSSO
IVRO is the principal alternative procedure but no longer frequently used because of poorer control of the condylar segments
The best way to induce bone formation is to….
In a cleft area, teen erupt and bring bone with them only if…
have a tooth erupt through the area and bring bone with it
they are moving through bone, not soft tissue, so a bone graft is required before tooth eruption occurs
What happens if the bone graft for a cleft palate patient was performed too early?
negatively affect future growth
What happens if you wait too long to place a bone graft for cleft palate patient?
bone dents to be lost on the surface of roots close to the defect
teeth adjacent to the cleft have an increased risk of periodontal pocketing and attachment loss
When is the ideal timing to place a bone graft for a cleft palate patient?
as late as possible in maxillary growth, but before eruption of the teeth adjacent to the cleft area (8-10 years old)
In order for the alveolar bone graft to be successfully, you need ___
nasal and oral mucosal coverage over the graft
Why is it difficult to procline upper incisors in cleft palate patients?
the upper lip is tighter and less adaptable than normal
How are posterior crossbites in cleft patients different than in normal patients?
Previous surgical intervention has produced tight palatal tissue that limits dental expansion.
No equivalent of mid palatal suture for orthopedic expansion
Dental expansion only which has high relapse tendency
Not all crossbites can be corrected orthodontically or surgically
Can bone grafts be used in a defective mid palatal area in a cleft patient? why?
No
if done at early age it will restrict maxillary growth.
If done after growth, it is diccult to place graft in poorly vascularize tissue that spans the palatal defect
If surgery is performed in late teens, a graft CAN be placed in the midline cleft when Mx is down fractured
When is a cleft lip closed?
in infancy
leads to partially collapsed nostril on the affected side that looks abnormal
When is a secondary nasal procedure done in cleft patients?
In adolescent to reviese the soft tissue at the same time as comprehensive orthodontics
When should orthognathic surgery be performed in cleft patients?
conclusion of active facial growth (18-19 M or 14 F)
If the initial palatal surgery is managed well (cleft patient) only ___% will have a severe enough residual deformity in the later teen years to need orthognathic surgery
5-10%
What are two limiting factors for surgery in cleft palate patients?
1) Residual scarring effects from previous surgery (can restrict tooth movement and Mx advancement)
2) Mx advancement can increase risk of producing post-surgical cleft palate speech.
Best camouflage cases work well with patients that have…
short to average face height, moderate malalignment and crowding, well-balanced between chin, nose, and lips
results deteriorate with increasing overjet and skeletal open bite tendency
Should the surgeon err on the side of too much or too little superior repositioning of the maxilla?
too little
If too much maxilla is impacted it will age the patient
Bad splits occur most commonly with which orthognathic surgical procedure?
BSSO
Less than 5% of the time
What is the most common location of a bad split in a LeFort 1 surgery?
pterygoid plates
Are antral and nasal fistulas more likely to occur along the midline or just lateral to the midline of the palate?
midline
If there is a significant difference (___mm) between the vertical height of the incisal edges and the occlusal level of the premolars, it should not be orthodontically flattened before surgery. This amount of orthodontic movement may relapse after surgery resulting in an anterior open bite
> 2m
What are three methods to improve vertical stability in a maxillary down graft procedure?
1) placement of heavy fixation bars from zygomatic arch to maxillary posterior teeth
2) interposiional placement of synthetic HA graft to provide mechanical rigidity
3) Use of simultaneous ramus osteotomy to minimize the stretching of the elevator muscles and decrease occlusal force until healing is more advanced.
What should be done if post-operative condylar resorption has occurred?
- no immediate action should be taken
- Do a rheumatoid and lupus screening
- treatment may be discontinued to not further load the joints
- splint therapy
- serial ceph tracking to evaluate further skeletal cahnges
- track cellular bone activity with technetium radioisotope bone scan (when resorption has stopped, pretreatment may be considered)
OSA is multifactorial. what are some of the factors?
craniofacial structures
neuromuscular tone
hormone fluctuation
obesity
rostral fluid shifts
genetic predisposition
In adults, the STOP-Bang questionnaire is useful for screening of OSA. what does STOP-Bang stand for?
S - snoring T - Tiredness O - observed pauses in breathing P - high blood pressure B - BMI greater than 35 Kgm3 A - Age greater than 50 N - Neck circumference greater than 17 (males ) or 16 in (female) G - Male gender
What are the three steps to observe the Modified Mallampati classification?
1) Pt in supine or seated postiion
2) protrude tongue as far as possible without sound
3) examiner evaluates relationship between palate, tongue base, and other soft tissue structures
What are the 4 different Mallampati classifications?
1 - soft palate, fauces, uvula, and tonsillar pillars visible
2 - soft palate, fauces, and uvula visible
3 - soft palate and base of uvula visible only
4 - soft palate not visible
Helpful as part of screening process but NOT indicative of severity of OSA
MMA (maxillomandibular advancement) is generally reserved to patients who have severe OSA and…
are unable to tolerate PAP therapy and have orthodontic reasons for surgery (not indicated for bimaxillary protrusive patients)
True or false… OSA has been shown in some children to stunt growth
true
What are the treatment options for pediatric OSA?
- removal of hypertrophic tonsils and adenoids
- pharmacologic agents to reduce size of nasal soft tissues
- nasal surgery (turbinate reduction and deviated septum correction)
- RPE and mandibular advancement appliances (only when indicated)
- no clear indication of prophylactic use of mandibular anterior repositioning appliances prevents later development of OSA
True or false… extraction to reduce the proclination of teeth have in some cases shown to constrict the upper airway very slightly
true.
however when crowding is performed to relieve dental crowding, there has been shown to have no effect or even an increase in overall volume
A mandibular anterior positioning appliance for OSA should protrude the mandible ___ to ___ of the patients maximum protrusive movement
1/2 to 2/3
The low cost, minimal invasive, conservative approach of oral appliances for treating OSA patients can be ideal for pts with ___ sleep apnea
mild to moderate
Those who have severe apnea but are unable or unwilling to tolerate CPAP and/or surgery, some improvement can be seen with oral appliances
True or false… oral appliances or treatment of OSA is well-tolerated by patients
true
True or false… patient who are treated with OSA oral appliances have a risk of minor alterations in occlusion, but very few will experience major problems
true
