17.2 Maxillofacial Trauma and Dentofacial Deformities
Key Takeaways
Trauma assessment follows the ATLS sequence: airway with cervical spine protection, breathing, circulation, disability and exposure, before any dental treatment.
Malocclusion, a step in the occlusal plane, a sublingual hematoma and lower lip paresthesia suggest a mandibular fracture; bilateral condylar fractures typically produce an anterior open bite.
Le Fort I separates the tooth-bearing maxilla horizontally, Le Fort II is a pyramidal fracture through the nasal bones and orbital floors, and Le Fort III is craniofacial dysjunction through the frontozygomatic sutures.
An orbital floor blow-out fracture causes diplopia on upward gaze from inferior rectus entrapment and enophthalmos; a trapped muscle in a child is an emergency because of the oculocardiac reflex.
Cleft lip is usually repaired at about 3 months and the palate at about 9-18 months, while secondary alveolar bone grafting is done at about 8-11 years before the permanent canine erupts.
The oral medicine and surgery section of the blueprint lists trauma and dentofacial deformities. Expect questions that ask you to recognize a fracture from its signs, to name the Le Fort level, to identify the airway risk, or to time cleft and orthognathic treatment.
Initial Assessment
Use the ATLS sequence: Airway with cervical spine protection, Breathing, Circulation and hemorrhage control, Disability (neurological status, Glasgow Coma Scale), Exposure. Airway threats in facial trauma include:
- Bilateral parasymphyseal fractures ("flail mandible"): the tongue loses anterior support and falls back.
- Posteriorly displaced midface fractures, hemorrhage, swelling, and aspirated teeth, dentures or fragments.
- Account for all teeth and prosthesis fragments; obtain a chest radiograph if any are missing.
Check tetanus status, document injuries carefully (including possible non-accidental injury), and refer facial fractures to oral and maxillofacial surgery.
Mandibular Fractures
Signs: malocclusion, step deformity of the occlusal plane or lower border, sublingual hematoma, mobility of segments, pain and trismus, and lower lip and chin paresthesia (inferior alveolar nerve injury).
- Unilateral condylar fracture: deviation of the mandible toward the fractured side on opening, premature contact on that side.
- Bilateral condylar fractures: anterior open bite with posterior premature contacts.
- Fractures through tooth-bearing areas are compound (open to the mouth through the periodontal ligament), so antibiotics are commonly given.
- Favorable versus unfavorable: muscle pull (masseter, temporalis, medial pterygoid elevating the posterior segment; mylohyoid and digastric depressing the anterior segment) either holds the fracture together or displaces it, depending on the fracture line direction.
Imaging: at least two views at right angles (panoramic plus posteroanterior mandible), or CT.
Management:
| Approach | Notes |
|---|---|
| Closed reduction with intermaxillary fixation (IMF) | Arch bars or IMF screws, commonly about 4-6 weeks; shorter with early mobilization for condylar fractures |
| Open reduction and internal fixation (ORIF) | Titanium miniplates along Champy's ideal lines of osteosynthesis (for example the superior border at the angle); allows early function |
| Condylar fractures in children | Usually conservative with early mobilization, because the condyle remodels well |
| Teeth in the fracture line | Retain if they aid reduction and are sound; extract if mobile, infected or preventing reduction |
Midface Fractures
| Fracture | Fracture line | Key signs |
|---|---|---|
| Le Fort I | Horizontal above the tooth apices through the maxilla, nasal septum and pterygoid plates | Mobile tooth-bearing segment ("floating maxilla"), malocclusion |
| Le Fort II | Pyramidal: nasal bones, medial orbital walls, orbital floors, zygomaticomaxillary sutures | Mobile midface including nose, bilateral periorbital bruising, infraorbital paresthesia, possible CSF rhinorrhea |
| Le Fort III | Craniofacial dysjunction through frontozygomatic sutures, orbits and nasal root | Elongated "dish face", whole midface mobile, CSF leak, airway risk |
| Zygomatic complex | Frontozygomatic suture, orbital floor and rim, zygomaticomaxillary buttress, arch | Flattened cheek, infraorbital nerve paresthesia, subconjunctival hemorrhage with no posterior limit, diplopia, trismus from a depressed arch impinging on the coronoid |
| Orbital floor blow-out | Isolated orbital floor | Diplopia on upward gaze (inferior rectus entrapment), enophthalmos, infraorbital numbness |
An isolated depressed zygomatic arch can be elevated through a temporal (Gillies) approach; displaced complex fractures need ORIF. In children, a "trapdoor" orbital floor fracture with entrapment can trigger the oculocardiac reflex (bradycardia, nausea, syncope) and needs urgent release.
Dentoalveolar Fractures
A mobile segment of alveolus with several teeth is repositioned under local anesthesia and splinted (commonly about 4 weeks); assess pulp status of involved teeth during follow-up.
Dentofacial Deformities
| Deformity | Typical features |
|---|---|
| Skeletal Class II | Mandibular retrognathia and/or maxillary prognathism; convex profile |
| Skeletal Class III | Mandibular prognathism and/or maxillary hypoplasia; concave profile |
| Vertical maxillary excess (long face) | Excessive gingival display, lip incompetence, skeletal open bite |
| Facial asymmetry | Condylar hyperplasia, hemifacial microsomia, trauma |
Combined orthodontic-surgical treatment:
- Pre-surgical orthodontics removes dental compensations (decompensation), which often makes the profile look temporarily worse.
- Orthognathic surgery after growth has finished (later in males than females): Le Fort I osteotomy to advance, impact or rotate the maxilla; bilateral sagittal split osteotomy (BSSO) to advance or set back the mandible (inferior alveolar nerve paresthesia is the main risk); genioplasty; distraction osteogenesis for large movements or growing patients.
- Post-surgical orthodontics to finish the occlusion, then retention.
Cleft Lip and Palate
- One of the most common congenital anomalies (on the order of 1 in 700 births worldwide), managed by a multidisciplinary team.
- Lip repair at about 3 months (the traditional "rule of tens": about 10 weeks, 10 pounds, hemoglobin 10 g/dL), palate repair at about 9-18 months before speech develops.
- Secondary alveolar bone grafting at about 8-11 years, before the permanent canine erupts (when its root is about one-half to two-thirds formed), so the canine can erupt through the graft.
- Associated dental anomalies: missing or peg-shaped lateral incisors, supernumerary teeth, crossbites and maxillary hypoplasia; some patients later need orthognathic surgery.
Exam Traps
- Sublingual hematoma after facial trauma means a mandibular fracture until proven otherwise.
- Deviation on opening is toward the side of a unilateral condylar fracture.
- Alveolar bone grafting is timed by canine root development, not by age alone.
After a fall onto the chin, a 22-year-old has bilateral preauricular pain, cannot bring the front teeth together, and has premature contacts only on the molars. What is the most likely injury?
A Le Fort III fracture, which always causes an anterior open bite without pain
Bilateral temporomandibular joint dislocation with the condyles locked anteriorly
An isolated fracture of the left mandibular body with a vertically favorable line
Bilateral condylar fractures, which characteristically cause an anterior open bite
A patient with a facial injury has a flattened left cheek, numbness of the left upper lip and side of the nose, a subconjunctival hemorrhage with no visible posterior limit and limited mouth opening. Which fracture is most likely?
Left zygomatic complex fracture
Le Fort I fracture with a floating tooth-bearing maxilla
Left mandibular angle fracture without displacement
Isolated nasal bone fracture with septal hematoma
A 9-year-old with a repaired unilateral cleft lip and palate has an alveolar cleft next to the developing permanent canine, whose root is about half formed. What is the usual next surgical step?
Le Fort I advancement now, because maxillary hypoplasia always worsens
Secondary alveolar bone grafting before the permanent canine erupts
Repeat palatoplasty, because the palate must be closed again at age 9
No treatment until adulthood, when implants can replace the canine
Sections you finish are checked off in the contents.