Orthognathic/Cleft/OSA Flashcards
Which of the following is not true in regards to epidemiology of isolated cleft lip?
A. Males > Females
B. 75% are unilateral
C. Caucasions > Asians > Africans
D. Incidence is 1:700 to 1:2000 live births
C. Caucasions > Asians > Africans
Cleft lip:
i. Males > Females (3 : 2)
ii. 75% unilateral, Left > Right
iii. L : R : Bilateral = 6 : 3 : 1
iv. Incidence of 1 : 700 to 1 : 2,000 live births.
v. Native Americans and Asians (1 : 500) > Caucasians (1 : 1,000) > African Americans (1 : 2,000).
Isolated cleft palate
i. Females > Males (2 : 1)
ii. Hard palate 75%
iii. 1 : 2,000 live births.
iv. Usually associated with other developmental abnormalities and syndromes
Which of the following is a pre operative esthetic concern when planning maxillary advancement?
A. obtuse nasolabial angle
B. 1mm tooth show at rest
C. narrow alar base
D. dorsal hump
B. 1 mm tooth show at rest
Le Fort advancement will lead to all of the following:
Upper lip eversion with a soft tissue-to-bone ratio up to 0.9 : 1 if utilizing a V-Y alar cinch closure. This will lead to increased incisor show
The alar base can widen, which can be avoided with a V-Y closure.
The nasal tip can rotate upward (1mm for every 6mm of superior movement of the central incisors). This may mask a dorsal hump.
More acute nasolabial angle.
Which artery supplies the maxilla after a le fort I downfracture?
A. Maxillary
B. Descending palatine
C. Facial
D. Ascending pharyngeal
D. Ascending pharyngeal
What direction is the osteotome placed when during pterygoid plate fracture?
A. medial, inferior, anterior
B. medial, superior, anterior
C. medial, inferior, posterior
D. medial, superior, posterior
A. medial, inferior, anterior
Which of the following is an indication for modified condylotomy?
A. Free up the disc
B. Increase the joint space
C. Reposition the condyle inferior to the disc
D. Advance the mandible
B. Increase the joint space
A modified condylotomy procedure consists of an intraoral vertical ramus osteotomy in which the medial pterygoid muscle is partially detached to allow for 3 to 4 mm of condylar sag. Ideally, the downward
position of the condylar segment increases the joint space, reducing the load on the retrodiscal tissue and
relieving the pain and dysfunction
Which artery is likely not involved in a bleeding complication during IVRO?
A. Masseteric
B. Inferior Alveolar
C. Facial
D. Superficial Temporal
D. Superficial Temporal
There are 3 arteries that can cause bleeding during an IVRO. If it’s a superior bleed, the source is the masseteric artery. If it’s a middle area bleed, the source is the inferior alveolar artery. If the bleed is coming from an inferior area, the source is the facial artery (this only really occurs if an external approach is used).
What muscle is affected during a sliding genioplasty?
A. Digastrics
B. Geniohyoid
C. Hyoglossus
D. Genioglossus
D. Genioglossus
Which of the following is not a phase during distraction osteogenesis?
A. Latency
B. Activation
C. Sequestration
D. Consolidation
C. Sequestration
Corticotomies are created and the device is activated to ensure appropriate engagement of the device and movement of the segments. The device is then deactivated to re-approximate the segments.
Latency period of 5-7 days in skeletally mature patients to allow formation of a fibrovascular bridge across the endosperm of the bony segments. This will support future bone formation during the distraction period. Waiting too long will result in premature fusion of the segments and then they cannot be distracted. Activating too soon can lead to a fibrous or non-union.
The activation period then begins. Patients typically are advanced 1.0mm per day by turning the device twice a day (0.5mm per turn).
If the distraction rate is too fast, a fibrous nonunion can form OMSITE question.
The consolidation period is the final phase, which should be twice the activation period.
Which of the following bones is formed by intramembranous ossification?
A. Iliac Crest
B. Ascending Ramus
C. Rib
D. Fibula
B. Ascending Ramus
The majority of the axial and appendicular skeleton undergoes endochondral ossification. The only parts of the facial skeleton that form via endochondral ossification are:
The coronoid and condylar process.
The styloid process.
The malleus, incus, and stapes.
The ethmoid and sphenoid bones.
The petrous part and mastoid of the temporal bone
The ramus
Distraction osteogenesis forms bone via intramembranous ossification
What is not an advantage of distraction osteogenesis vs. le fort advancement in a cleft patient?
A. More movement can be accomplished
B. Less soft tissue hindrance on the osseous movement
C. Less concern of vascular compromise
D. Increased soft tissue advancement
D. Increased soft tissue advancement
Distraction osteogenesis gives you the ability to move larger distances without soft tissue issues.
CL/P patients have lots of palatal scarring from previous surgeries (pharyngeal flaps, alveolar grafting) that limits the amount of advancement and causes relapse. With previous surgeries, the anatomy has changed and the vascular supply is usually compromised as well. LeFort I surgery in CL/P patients can also worsen VPI
With distraction osteogenesis, born forms in the same manner as a fracture heals. A hematoma forms at the center of the corticotomy. This becomes a callus with woven bone. The callus undergoes ossification, so the woven bone matures to lamellar bone. The final stage is remodeling.
Which artery is most likely to be injured during the down fracture of a le fort osteotomy?
A. Ascending pharyngeal
B. Descending palatine
C. Nasopalatine
D. Sphenopalatine
B. Descending palatine
Descending palatine artery
º Descends through the pterygopalatine canal, emerging from the greater palatine
foramen
º A Le Fort I osteotomy breaks the pterygopalatine canal horizontally, placing the
vessel at risk
º An overt injury results in brisk bleeding that must be controlled with ligation
º An occult injury can result in delay bleeding
What is the most esthetic nasolabial angle in females?
A. 90-105 degrees
B. 95-110 degrees
C. 100-115 degrees
D. 105-120 degrees
B. 95-110 degrees
Females should have a nasolabial angle of 95-110 degrees.
Males should have a nasolabial angle of 90-105 degrees.
Which procedure is performed to prevent nasal deformity after a maxillary impaction?
A. V to Y closure
B. Nasal tip graft
C. Alar cinch suture
D. Septoplasty prior to plating
C. Alar cinch suture
An alar cinch suture will prevent widening of the nasal base.
V-Y advancement prevents loss of the visible vermillion.
What is the ideal holdaway ratio in white females?
A. 1:1
B. 0.5:1
C. 2:1
D. 1:2
B. 0.5:1
*Holdaway ratio - used to assess whether the chin is too recessed or too prominent compared to the position of the lower incisors.
1. Draw a line that crosses N and B (NB)
2. Measure the distance from NB to the incisal edge of the mandibular incisor and the distance from NB
to Pog
3. Calculate the ratio of the distances (NB to incisal edge of mandibular incisor:NB to Pog)
* The ideal ratio for white males is 1:1; for white females it is 0.5:1
