Facial Trauma Flashcards
1
Q
What is the craniofacial ratio in adulthood
A
0.0840277777777778
2
Q
What is the craniofacial ratio at birth
A
0.334027777777778
3
Q
How many deciduous teeth are there
A
20
4
Q
In an adult, what # is the right 3rd molar of the mandible
A
32
5
Q
What is the appropriate tetanus prophylaxis for a patient with a tetanus-prone wound, who has not been previously immunized
A
0.5 ml absorbed toxoid and 250 units of human tetanus immune globulin.
6
Q
What is the proper tetanus prophylaxis for a patient with a tetanus-prone wound, who last received a booster 7 years ago’
A
0.5 ml absorbed toxoid.
7
Q
What do “microplates” refer to
A
1.0 mm screw applications.
8
Q
In what % of the population is the nasofrontal duct a true duct
A
15% (in 85% it exists as a foramen draining directly into the nasal cavity).
9
Q
How long should immobilization typically be maintained in children
A
2 - 3 weeks.
10
Q
Where is this located in relation to the lateral canthus
A
2 em inferior.
11
Q
What do “miniplates” refer to
A
2.0 mm, 1.5 mm, or 1.3 mm screw applications.
12
Q
What % of mandible fractures are associated with cervical spine injury
A
2.6%.
13
Q
What post-orbital fracture visual acuity scores are associated with a return to normal acuity after treatment
A
20/400 or better.
14
Q
Where are the anterior and posterior ethmoid arteries and optic canal in relation to the anterior lacrimal crest
A
24 - 12 - 6 rule: anterior ethmoid artery is approximately 24 mm posterior to the lacrimal crest; the posterior ethmoid artery is 12 mm posterior to the anterior ethmoid artery; the optic canal is 6 mm posterior to the posterior ethmoid artery.
15
Q
What is the typical long-term interincisal opening after surgical correction of TMJ ankylosis
A
25 - 28 mm.
16
Q
What % of patients with ZMC fractures have other associated facial injuries
A
25%.
17
Q
What % of thoracic perforations will be missed with water-soluble contrast agents
A
25%.
18
Q
What is the incidence of permanent scleral show with the subciliary approach
A
28%.
19
Q
What is the normal intercanthal width
A
30 - 35 mm in Caucasians or roughly the width of the alar base.
20
Q
How far posterior should dissection proceed when placing a Medpor implant for defects of the posterior convex orbital floor
A
4 em.
21
Q
What % of mandible fractures are associated with other injuries
A
40 - 60%.
22
Q
What is the average depth of the orbit
A
40 -50 mm.
23
Q
What is normal interincisal opening
A
40 -50 mm.
24
Q
What % of cervical perforations will be missed with water-soluble contrast agents
A
50%.
25
What are the indications for endoscopic optic nerve decompression after facial trauma
66% reduction in amplitude of the visual-evoked response, loss of red color vision, bony impingement on the optic canal, afferent papillary defect.
26
What is the incidence of persistent diplopia after orbital reconstruction
7%.
27
What is the incidence of infection after mandible fracture
7%.
28
Cerebral perfusion-directed therapy attempts to maintain CPP at or above what
70 mm Hg.
29
What is the sensitivity of barium in detecting perforations
80- 90%.
30
How much force is required to fracture the frontal sinus
800 - 2200 lbs.
31
How are they numbered
A to T.
32
What is the best way to treat mandible fractures in infants
Acrylic splints x 2 - 3 weeks.
33
What is the "bowstring sign"
An obvious give that occurs with lateral tension on the lower lid, indicating disruption of the medial canthal tendon.
34
What is the most likely mechanism of injury for bilateral condylar fractures
Anterior blow to the chin.
35
What are the 3 limbs of the medial canthal tendon
Anterior, superior and posterior limbs.
36
What are the contraindications to primary closure of bites
Any human bite; animal bites seen after 5 hours of injury; all avulsion injuries from any animal bite.
37
What are the weakest areas of the mandible
Area around the 3rd molar, socket of the canine tooth, and the condyle.
38
What is the strongest predictor of negative outcome in trauma patients
Arterial hypotension
39
Where are inferiorly positioned plates placed
At the inferior border of the mandible to avoid the neurovascular bundle.
40
What is the treatment for a nondisplaced posterior table fracture with a CSF leak
Bed rest with head elevation +/lumbar drain; cranialization considered if not resolved after 5 - 7 days.
41
What is the general approach for repair of panfacial fractures
Begin laterally, work medially, and correct NOE and nasal septal fractures last; frontal fractures should be repaired before midface fractures.
42
What is the general approach to repair of LeFort III fractures
Begin stabilization at the cranium then work caudally.
43
What are the relative indications for open reduction of a condylar fracture
Bilateral condylar fractures in an edentulous patient when M MF is impossible, condylar fractures when MMF is not recommended for medical reasons, bilateral condylar fractures associated with midface fractures.
44
Anterior open bite suggests which type of fracture
Bilateral condylar fractures.
45
What is the most serious complication after orbital reconstruction
Blindness.
46
What can be done for trismus that does not respond to brisement force
C oronoidectomies.
47
Which tooth has the longest root
Canine.
48
What is a type I I NOE fracture as described by Markovitz et al
Comminuted, but identifiable, central fragment.
49
What is a type C ZMC fracture
Complex fracture with comminution of the zygomatic bone.
50
Which mandible fractures require ORI F with bicortical screws
Complex open fractures that are displaced, comminuted, or infected.
51
Rigid fixation is based on what two means of stabilization
Compression and splinting.
52
Why should compression plates be over-contoured by 3° - 5°
Compression at the buccal surface tends to produce spreading on the lingual side; over-contouring will overcome this.
53
Which parts of the mandible are most commonly fractured
Condyle (36°/o), body (21°/o), and angle (20%).
54
Which part of the mandible is most commonly fractured in children
Condyle.
55
What are the typical physical findings of a unilateral condylar neck fracture
Contralateral open bite and ipsilateral chin deviation.
56
What is the "workhorse" for exposure of the nasoethmoidal region
Coronal approach.
57
What is the indication for surgical treatment of isolated anterior table fractures
Cosmetic deformity.
58
What is the definition of cerebral perfusion pressure (CPP)
CPP = mean arterial pressure (MAP) - intracranial pressure (ICP).
59
What are the potential complications of endoscopic optic nerve decompression
CSF leak, carotid artery injury, transection of the ophthalmic artery, orbital fat herniation.
60
What is a potential complication of this approach
Damage to the temporal fat pad, resulting in temporal wasting.
61
Which teeth can be used in children between the ages of 5 and 8 for immobilization
Deciduous molars.
62
What are the most common injuries associated with facial trauma in children
Dental injuries.
63
What are the 3 approaches to zygomatic arch fractures
Direct percutaneous, temporal (Gillies), and hemicoronal approaches.
64
What is the treatment of choice for an edentulous 40-year-old epileptic man who sustains a LeFort I fracture during a seizure
Direct wiring of the zygomaticomaxillary buttresses.
65
When is cranialization required for treatment of frontal sinus fractures
Displaced posterior table fractures with a CSF leak or significantly comminuted posterior table fractures.
66
What are the indications for frontal sinus obliteration in the presence of a fracture
Displaced posterior table fractures with involvement of the nasofrontal duct.
67
What are the absolute indications for open reduction of a condylar fracture
Displacement of the fractured fragments into the middle cranial fossa, inadequate reduction with MMF, lateral extracapsular displacement of the condyle, foreign body (ie, bullet) embedded in the joint.
68
What is the most likely cause of cyclovertical diplopia following repair of a NOE fracture
Disruption of the trochlea.
69
When approaching the frontozygomatic buttress through the hemicoronal incision, how is the temporal branch of the facial nerve avoided
Dissection begins just superficial to the superficial layer of the deep temporal fascia; 2 em above the zygomatic arch, the dissection is carried deep to the superficial layer of the deep temporal fascia.
70
What is the plane of dissection with the Gillies approach
Dissection is carried out between the temporalis muscle and its overlying fascia.
71
What are the only plates that can bear the stress of mastication during healing
Eccentric dynamic compression plates.
72
What is the most common complication after orbital reconstruction
Enophthalmos.
73
What is the most helpful test for evaluation of aerodigestive injuries caused by transcervical gunshot wounds
Esophagram with water-soluble contrast agent followed by barium.
74
T/F: Patients with titanium implants cannot undergo MRI
False.
75
What materials can be used to obliterate the frontal sinus
Fat, muscle, fascia, or cancellous bone; can also allow spontaneous osteogenesis after burring the inner cortices.
76
Your patient has a fracture of the mandibular body and a comminuted midface fracture. How do you approach reconstruction
First MMF, then ORlF the mandible, then ORlF the midface.
77
Your patient has a fracture of the condylar head and mandibular body and a comminuted midface fracture. How do you approach reconstruction
First ORIF the midface, then place the patient into MMF, then ORIF the mandibular body fracture.
78
When should lag screws be used to reduce a fracture
For an oblique fracture with an intact inner fragment where the length of the fracture is at least twice the thickness of the bone.
79
When are serial explorations indicated after penetrating injuries to the face
For high-energy gunshot or rifle (\> 1200 ft/s) injuries, shotgun injuries, and high-energy avulsion injuries.
80
What test is performed to evaluate for entrapment of the extraocular muscles
Forced duction test.
81
What is brisement force
Forced jaw opening under anesthesia; usually successful for treatment of trismus that does not respond to physiotherapy.
82
What is a class I mandible fracture
Fracture between two teeth.
83
What is a class Ill mandible fracture
Fracture in an edentulous area.
84
What are the absolute indications for surgical repair of frontal sinus fractures
Fractures involving the nasofrontal duct and significantly displaced posterior table fractures with or without dural tear and CSF leak.
85
What are favorable fractures
Fractures where the muscles tend to draw the fragments together.
86
What material is used for grafting
Fresh autogenous particulate marrow.
87
At what ages are deciduous teeth present
From 20 months unti I age 5 - 6.
88
What are the horizontal buttresses of the midface
Frontal bar and cranial base, zygomatic arch and temporal process of the zygoma, maxillary palate and alveolus, and the greater wing and pterygoid plates of the sphenoid.
89
Reduction of which buttresses is essential to restore upper facial width
Frontozygomatic buttresses.
90
Transcatheter arterial embolization is most useful in the management of what type of neck injury
Gunshot wound (GSW) to zone III of the neck.
91
What are the advantages of using cranial bone as an autogenous graft compared to other bone grafts for orbital reconstruction
Harvested from the same surgical field~ little postoperative pain; donor site complications are rare; large amounts can be harvested: less likely to resorb than endochondral grafts.
92
What are the 3 approaches to the frontozygomatic buttress
Hemicoronal, lateral brow, and the upper blepharoplasty incisions.
93
Due to these differences, which facial fractures are more common in children than in adults
High facial fractures (orbital roof, temporal bone fractures).
94
In an adult, what # is the left 3rd molar of the mandible
I 7.
95
A supraclavicular stab wound is in which neck zone
I.
96
When is diplopia likely to persist after orbital reconstruction
If diplopia occurs within 30 degrees of the primary position.
97
What is the optimal treatment for a nondisplaced condylar fracture
If occlusion is normal, soft diet and close observation; bilateral fractures or unilateral fractures with malocclusion should be treated with M M F for 3 weeks, then elastics for 2 weeks.
98
What is the normal inclination of the orbital floor
Inclines superiorly at a 30-degree angle from anterior to posterior and at a 45-degree angle from lateral to medial.
99
What is the most common cause of loss of vision after reduction of facial fractures
Increased intraorbital pressure, usually secondary to venous congestion.
100
What are the sequelae of untreated lateral zygomatic arch fractures
Increased midfacial width and malar flattening.
101
What are the disadvantages of the retroseptal approach
Increased risk of injury to the inferior oblique muscle and prolapse of orbital fat into the surgical field.
102
What are the most common causes of delayed healing and non-union
Infection and noncompliance.
103
The "zone of compression" refers to which area of the mandible
Inferior border of the mandible.
104
What are the contraindications to orbital exploration after orbital trauma
Injury to an only-seeing eye; presence of hyphema, globe injury, or retinal tear; and medical instability.
105
What is a type B ZMC fracture
Injury to each of the 4 supporting structures.
106
What are the treatment options for children between 2 and 5 years of age
Interdental eyelet wiring, arch bars, cap splints, or soft diet.
107
What are the 3 types of condylar fractures
Intracapsular crush fractures of the condylar head, high condylar fractures through the neck above the sigmoid notch, and low subcondylar fractures.
108
Among children, which mandible fractures result in the highest incidence of dentofacial abnormalities
Intracapsular crush fractures of the condyle.
109
What is a type A ZMC fracture
Isolated to one component of the tetrapod structure (zygomatic arch, lateral orbital wall, or inferior orbital rim).
110
Why is the midface inherently prone to deficient projection
It lacks good sagittal buttresses.
111
What is an open bite
Lack of anterior incisal contact when the posterior teeth are in occlusion.
112
What sort of plates should be used in the severely atrophic mandible
Large reconstruction plates.
113
What sort of plates should be used with comminuted mandible fractures
Large reconstruction plates.
114
In cases of panfacial fractures, when should NOE fractures be repaired
Last.
115
What can be done to improve exposure with the transconjunctival approach
Lateral canthotomy with cantholysis.
116
What is the best anatomic guide to reconstruction of the length and medial position of the zygomatic arch
Lateral orbital alignment.
117
On physical exam, the nose and the maxillary alveolar process are found to be free-floating. What type of fracture has occurred
LeFort 11.
118
Which of the LeFort fractures involves the infraorbital rim
LeFort II.
119
What is the major advantage of immediate aggressive reconstruction after a high-energy GSW to the face
Less soft tissue scarring and contracture.
120
What are miniplates
Lightweight, compression-neutral plates designed to be used with self-tapping screws.
121
Which of these is most common
Low subcondylar fracture (often incomplete or "greenstick" injury).
122
What is the most prominent portion of the ZMC
Malar eminence.
123
What are the potential complications from untreated nasofrontal duct fractures
Meningitis. mucopyocele, intracranial abscess.
124
What are the sequelae of untreated maxillary fractures
Midface retrusion, facial elongation, and anterior open bite deformity.
125
What type of screws are used to secure superiorly positioned plates
Monocortical to prevent damage to tooth roots.
126
What are the advantages of the subciliary approach
More direct, requires less understanding of orbital anatomy, and provides more exposure than the transconjunctival approach.
127
What factors lead to infection of mandible fractures
Moving fragments, foreign bodies, dead bone.
128
What are the 3 paired vertical buttresses of the midface
Nasomaxillary, zygomaticomaxillary, and pterygomaxillary.
129
Compared to adults, children are at a higher risk for what type of injury after penetrating injuries to the face and neck
Neurological injury.
130
What are the advantages of using mesh implants for repair of orbital floor fractures
No need for a bone or fascial barrier between the orbital contents and the mesh; posterior orbital shape can be simulated more easily than with bone grafts; well tolerated when exposed to open paranasal sinuses; may facilitate survival of bone grafts in the anterior orbit.
131
What are the advantages of the Gillies approach
No visible scar, protects the temporal branch of the facial nerve, and allows bimanual reduction.
132
What sort of neurologic sequelae usually result from isolated unilateral vertebral artery injury
None.
133
4 weeks after ORIF of a mandibular body fracture, your patients presents with an exposed plate and purulent drainage. The reduction is grossly intact. What do you do
Open wound, remove involved tooth if applicable, remove hardware, and assess union; if nonunion is present, most patients will heal with MMF; other option is plate and bone graft (external approach).
134
10 days after ORIF of a mandibular body fracture, your patient presents with an exposed plate and purulent drainage. The reduction is grossly intact. What do you do
Open wound, remove involved tooth if applicable; if hardware is loose, replace it with a new plate; if hardware is rigid, continue drainage, wound care.
135
What is the weakest part of the entire ZMC complex
Orbital floor.
136
What would be the optimal treatment for a 25-year-old man with a LeFort I fracture, bilateral dislocated subcondylar fractures, and a comminuted left parasymphyseal fracture
ORIF of the parasymphyseal fracture, ORIF of one subcondylar fracture, and MMF for 3 weeks.
137
What is the preferred donor site for bone grafting in the repair of NOE fractures
Outer or inner table of the parietal skull.
138
What is the difference between overbite and overjet
Overbite occurs in the vertical plane whereas overjet occurs in the horizontal plane.
139
What problem may arise in the edentulous, denture-wearing patient after mandible fracture with mental nerve disruption
Patients who wear a complete mandibular denture require gingival sensation; in the presence of bilateral mental nerve paresthesia, it may be impossible for the patient to tolerate a mandibular denture.
140
In patients with mandible fractures, what mechanisms of injury are most predictive of an associated cervical spine injury
Penetrating high-velocity gunshot injury; high-velocity MV A.
141
What makes up the superior portion of the bony nasal septum
Perpendicular plate of the ethmoid.
142
What is the most effective treatment for entropion that fails to resolve with massage
Placement of a spreader graft (ie, palatal mucosal graft) in the posterior lamella.
143
What is the most common cause of infection after ORlF
Poor plating technique.
144
Where should the point of attachment of the medial canthal tendons be directed
Posterior and superior to the lacrimal fossa to avoid telecanthus and blunting of the medial canthal area.
145
Which table of the frontal sinus is thinner
Posterior.
146
What is the appropriate management for a deep puncture wound from a dog or cat bite
Post-exposure rabies prophylaxis should be considered for all bites. If the animal is healthy, it should be quarantined for I 0 days to exclude rabies. If the animal is unavailable or suspected rabid, immediate vaccination and immunoglobulin therapy should be administered. In addition, antibiotic coverage to include Pasteurella multocida, should be initiated.
147
What are the 2 transconjunctival approaches
Preseptal and retroseptal.
148
Which teeth can be used in children between the ages of 7 and 1 1 for immobilization
Primary molars and incisors.
149
What are the advantages to the preseptal approach
Protection of the inferior oblique muscle and periorbita.
150
What is the most sensitive test to detect optic nerve injury after facial trauma
Pupillary reaction to light.
151
How is stabilization by splinting performed
Reconstruction plates with bicortical screws.
152
What is the treatment for infected extraoral mandibular ORI F
Removal of the tooth and the failed plate, debridement of dead bone, placement of a large reconstruction plate, and primary grafting if inadequate bone contact exists.
153
How can one repair a floating palate when the anterior and lateral walls of the maxilla are severely comminuted
Replace the comminuted bone with a bone graft fixed to the alveolar ridge and infraorbital rim.
154
Which of these involves an incision in the fornix directly into the orbital fat
Retroseptal.
155
What are the advantages of using Medpor over other alloplastic materials for orbital reconstruction
Semi-rigid; porous allowing fibrous, vascular, and bony ingrowth; minimal inflammatory reaction; infection and extrusion are rare.
156
What is a type Ill NOE fracture as described by Markovitz et al
Severely comminuted fracture with disruption of the medial canthal tendon or too small of a central fragment to be repaired directly.
157
What is a type I NOE fracture as described by Markovitz et al
Single, noncomminuted central segment fracture.
158
What is the primary disadvantage to the preseptal approach
Slightly higher risk of lower-lid entropion.
159
What is the usual treatment of condylar fractures in children
Soft diet.
160
In a child, what is the treatment for an incomplete monocortical crack of the mandibular body with normal occlusion and movement
Soft diet.
161
Why are fractures of all 4 segments called "tripod" and not "tetrapod" fractures
Some consider the medial attachment to the maxilla and the deep attachment to the sphenoid bone as a single unit.
162
What are the approaches to ORIF of condylar fractures
Submandibular or retromandibular (most common); intraoral; preauricular face lift • • • InCISIOn.
163
Which radiographic view is best for visualizing the zygomatic arches
Submental vertex.
164
What are the 4 bony attachments to the skull radiating from the malar eminence
Superior attachment to the frontal bone (frontozygomatic suture); medial attachment to the maxilla (zygomaticomaxillary suture); lateral attachment to the temporal bone (zygomaticotemporal suture); and a deep attachment to the greater wing of the sphenoid (zygomaticosphenoidal suture).
165
The "zone of tension" refers to which area of the mandible
Superior border of the mandible.
166
Which of these covers the lacrimal fossa
Superior limb.
167
What are the horizontal buttresses of the nasoethmoidal region
Superiorly, the frontal bone and bilateral superior orbital rims; inferiorly, the bilateral inferior orbital rims.
168
A patient presents to you with TMJ ankylosis after repair of a condylar fracture. What should be done
Surgical correction ( interpositional arthroplasty, costochondral grafting, total joint prosthesis) followed by vigorous physical therapy.
169
What is a class II mandible fracture
Teeth are present on only one side of the fracture.
170
What are the indications for extraction of teeth in mandibular fracture lines
Teeth that are grossly mobile, have fractured roots, have advanced dental caries and periapical pathology, have soft-tissue pathology, or that hinder fracture reduction.
171
What determines the projection of the upper face
The frontal bar (supraorbital rims and frontal sinuses).
172
Which part of the lacrimal system is most vulnerable to injury
The inferior canaliculus near the medial canthal tendon.
173
What is an anterior crossbite
The maxillary incisors are lingual to the mandibular incisors.
174
What is a posterior crossbite
The maxillary or mandibular posterior teeth are either buccal or lingual to normal.
175
What is class III occlusion
The mesiobuccal cusp of the 1st maxillary molar lies posterior to the mesiobuccal groove of the mandibular 1st molar.
176
What is class II occlusion
The mesiobuccal cusp of the maxillary 1st molar lies anterior to the mesiobuccal groove of the mandibular I st molar.
177
What is class I occlusion
The mesiobuccal cusp of the maxillary I st molar articulates with the mesiobuccal groove of the mandibular I st molar.
178
What is the significance of the canals of Breschet
The mucosa lining these canals can be a potential origin for mucocele formation.
179
What does survival of a free fat graft in the frontal sinus depend on
The number of transferred pre-adipocytes.
180
What are the vertical buttresses of the nasoethmoidal region
The paired.. central fragments" arising from the frontal process of the maxilla and internal angular process of the frontal bone.
181
After MMF for a condylar fracture, your patient complains of deviation of his jaw on opening. What should be done
The patient should look in the mirror while opening the jaw and practice forcing himself to open without deviation. The deviation can be overcome with these • exerctses.
182
How is closed reduction achieved in edentulous patients
The patient's dentures are wired to his or her jaws using circummandibular and circumzygomatic wires or screws. Gunning splints are used if dentures are not available.
183
What is the difference in tooth viability when comparing plates versus wires for fixation of mandible fractures
There is a significant increase in the nonviability of teeth in the line and adjacent to fractures of the mandible treated by plates compared to those treated with • wtres.
184
Which plating material has been shown to have significantly less streak artifacts on CT scans
Titanium (as compared to stainless steel and vitallium).
185
Which approach to the inferior orbital rim involves cutting the capsulopalpebral fascia
Transcon j unctival.
186
What are the 3 approaches to the inferior orbital rim/orbital floor
Transconjunctival, subciliary, and rim incisions.
187
What is the most common cranial nerve injury after low-velocity GSW to the paranasal sinuses
Trigeminal nerve.
188
What is the indication for reduction of coronoid process fractures
Trismus secondary to impingement of the fractured fragment on the zygoma.
189
T/F: The medial pterygoid muscle elevates the jaw
True.
190
T/F: After mental nerve injury, sensation usually returns even without repair
True.
191
T/F: A mandible fracture in a child is much more likely to be associated with other injuries than in an adult
True.
192
What does "dynamic compression" refer to
Two-plate system (compression and tension plates).
193
Which of these is least common
Type A.
194
How does Markovitz's classification assist with management
Type I fractures usually can be repaired with microplates; type II fractures usually require transnasal wires in addition to plate fixation; type III fractures usually require at least 2 sets of transnasal wires and may require bone grafting.
195
On physical examination, digital pressure on the nasal tip causes prolapse of the distal nose into the pyriform aperture. Which type of NOE fracture is this according to Gruss' classification of NOE injuries
Type II
196
What is the most appropriate approach for exposure of the inferior maxillary buttresses
Upper labial buccal sulcus incision.
197
What is the significance of the presence of a CSF leak when assessing a patient with a frontal sinus fracture
Usually associated with a displaced posterior table fracture and a dural tear.
198
Where is the opening of the nasofrontal duct in the frontal sinus
Usually in the posteromedial floor of the sinus.
199
What are the indications for surgical exploration after ZMC injury
Visual compromise, EOM entrapment, globe displacement, significant orbital floor disruption, displaced or comminuted fractures.
200
After carotid artery injury, when is it too late to attempt revascularization
When coma has occurred beyond 3 hours, if an anemic infarction has occurred, or if no vascular back flow is present.
201
When is stabilization by splinting performed
When compression is impossible ( eg, inadequate fracture surface area, atrophic edentulous fractures, comminuted fractures, and defect fractures).
202
When are bone grafts used in the repair of anterior table fractures
When gaps \> 4 - 5 mm are present.
203
After high-energy avulsion injuries to the face, when is reconstruction of missing bone and soft tissue initiated
When no further necrosis is seen at reexploration of the wound.
204
When can bicortical plates be used in children
When permanent dentition is present.
205
What are the indications for open reduction of condylar fractures in children
When the fractured condyle directly interferes with jaw movement; when the fracture reduces the height of the ramus and results in an open-bite deformity; when the condyle is dislocated into the middle cranial fossa.
206
What are the advantages of using miniplates over wires in reducing fractures of the ZMC
Wires only stabilize in the x plane whereas miniplates add stabilization in all 3 spatial planes (x, y, z); wires are difticult to place in free-floating pieces of bone; wires require exposure of the deep surface of the bone.
207
What is the difference in the mechanism of healing between fractures repaired with MMF and fractures repaired with ORIF
With MMF, a callus, formed via micromovement of the fractured ends, bridges the fractured ends together; with ORIF, no callus is formed, and the fracture heals via direct bone growth.
208
Which of these is strongest
Zygomaticofrontal buttress.
209
Reduction of which buttresses is essential to restore the midfacial length
Zygomaticomaxillary and nasomaxillary buttresses.
