Mandible Flashcards
A 55-year-old woman is referred to the office by her dentist because of a 6-week history of exposed intraoral bone. She takes zoledronic acid for osteoporosis. Physical examination shows a 1-cm ulceration of gingiva with exposed necrotic bone adjacent to the right premolar. No infection or fistulization is noted. In addition to meticulous oral hygiene, which of the following is the most appropriate management?
A) Administration of prophylactic oral antibiotics
B) Curettage and bone grafting
C) Dental extraction
D) Segmental resection
E) Observation only
E) Observation only
The most appropriate management is observation only. The clinical vignette illustrates a case of Stage I bisphosphonate-related osteonecrosis of the jaw (BRONJ). These patients are typically asymptomatic, with the exception of exposed and/or necrotic bone. Antibiotics are not recommended unless there is infection (Stage II or III). Stage II BRONJ features exposed and/or necrotic bone with pain and local infection. Segmental resection is reserved for Stage III BRONJ. In general, the need for surgery is guided by the severity of the stage. Stage III BRONJ is characterized by exposed and/or necrotic bone with pain, infection, and the presence of another complication, such as osteolysis extending from the superior to the inferior border of the mandible, pathologic fracture, or extraoral fistula.
Stage I bisphosphonate-related osteonecrosis of the jaw
Stage I bisphosphonate-related osteonecrosis of the jaw (BRONJ). These patients are typically asymptomatic, with the exception of exposed and/or necrotic bone.
Stage I bisphosphonate-related osteonecrosis of the jaw
Observation
Stage II bisphosphonate-related osteonecrosis of the jaw: Management
Stage II BRONJ features exposed and/or necrotic bone with pain and local infection.
Stage II bisphosphonate-related osteonecrosis of the jaw
Antibiotics
Stage III bisphosphonate-related osteonecrosis of the jaw: Management
Stage III BRONJ is characterized by exposed and/or necrotic bone with pain, infection, and the presence of another complication, such as osteolysis extending from the superior to the inferior border of the mandible, pathologic fracture, or extraoral fistula.
Stage III bisphosphonate-related osteonecrosis of the jaw: Management
Segmental resection, antibiotics
A 33-year-old woman is brought to the emergency department after sustaining injuries in a motor vehicle collision. The patient notes pain on opening her mouth. Physical examination shows bilateral facial swelling and loss of posterior facial height. An anterior open bite is also noted. Which of the following additional findings on physical examination is most likely to suggest a bilateral subcondylar fracture in this patient?
A) Bilateral facial numbness
B) Bilateral mastoid ecchymosis
C) Blood in the external auditory canal
D) Clear fluid in the external auditory canal
E) Preauricular pain
E) Preauricular pain
Bilateral subcondylar fractures result in premature occlusion of the posterior teeth along with an anterior open bite, loss of posterior facial height, and bilateral facial swelling with pain on mouth opening. These findings occur because the subcondylar fracture interrupts the integrity of the vertical buttress. The lateral pterygoid muscles displace the condylar necks medially and anteriorly, allowing the unopposed vertical action of the temporalis and masseter muscles to shorten the posterior facial height. Swelling bilaterally would be expected in this fracture, and opening would displace the fracture line, causing pain.Bilateral facial numbness suggests a fracture of the ramus or body as the inferior alveolar nerve traverses these areas. Blood in the external auditory canal suggests a fracture more proximal than subcondylar. Bilateral mastoid ecchymosis and/or clear fluid in the external auditory canal suggest a skull base fracture.
Clinical presentation of bilateral subcondylar fracture
Bilateral subcondylar fractures result in premature occlusion of the posterior teeth along with an anterior open bite, loss of posterior facial height, and bilateral facial swelling with pain on mouth opening. Swelling bilaterally would be expected in this fracture, and opening would displace the fracture line, causing pain.
Anatomical reason behind clinical presentation of bilateral subcondylar fracture
These findings occur because the subcondylar fracture interrupts the integrity of the vertical buttress.
The lateral pterygoid muscles displace the condylar necks medially and anteriorly, allowing the unopposed vertical action of the temporalis and masseter muscles to shorten the posterior facial height.
Bilateral facial numbness suggests what injury?
Bilateral facial numbness suggests a fracture of the ramus or body as the inferior alveolar nerve traverses these areas.
Bilateral mastoid ecchymosis and/or clear fluid in the external auditory canal suggest what injury?
Bilateral mastoid ecchymosis and/or clear fluid in the external auditory canal suggest a skull base fracture.
Subcondylar fracture interrupts the integrity of the _______ buttress.
Subcondylar fracture interrupts the integrity of the vertical buttress.
A 25-year-old man is brought to the emergency department 2 hours after being punched in the left side of the face. Physical examination shows swelling on the left side of the face. The panoramic x-ray study (Panorex) shown was obtained (Fracture of the 3rd mandibular molar root). Which of the following is the most appropriate management?
A) Extraction of all components of the third left mandibular molar and maxillomandibular fixation (MMF) for 2 weeks
B) Extraction of all components of the third left mandibular molar and MMF for 6 weeks
C) Extraction of all components of the third left mandibular molar, MMF, and open reduction and internal fixation (ORIF)
D)Ligating the third left mandibular molar to the adjacent tooth for stability, MMF, and ORIF
E) Preservation of the third molar, MMF, and ORIF
C) Extraction of all components of the third left mandibular molar, MMF, and open reduction and internal fixation (ORIF)
The x-ray study shows a fracture of the root, thus the tooth and root must beremoved. Indications for extraction of a tooth in the line of a fracture include the need for MMF to regain the patient’s occlusion. The left parasymphyseal and comminuted left angle fractures can be managed in a number of ways, but the parasymphyseal fracture requires open reduction and internal fixation to prevent lateral displacement of the left mandibular body by the masseter muscle.
Management of parasymphyseal fractures
A parasymphyseal fracture requires open reduction and internal fixation to prevent lateral displacement of the left mandibular body by the masseter muscle.
A 2-month-old male infant is brought to the office because of mid face hypoplasia, craniosynostosis, and bilateral hand and foot anomalies. A photograph of the left foot is shown (syndactyly). This patient most likely has which of the following syndromes? A) Apert B) Crouzon C) Goldenhar D) Nager E) Treacher Collins
A) Apert
The patient described has Apert syndrome. This autosomal dominant syndrome is characterized by bicoronal craniosynostosis that leads to turribrachycephaly, mid face hypoplasia, and complex hand and feet syndactyly.
Apert syndrome: Heredity
Autosomal dominant
Apert syndrome: Craniosynostosis
Bicoronal craniosynostosis that leads to turribrachycephaly
Apert syndrome: Associations
Bicoronal craniosynostosis that leads to turribrachycephaly, mid face hypoplasia, and complex hand and feet syndactyly.
Crouzon syndrome: Heredity
Autosomal dominant disorder
Crouzon syndrome: Craniosynostosis
Craniosynostosis involving the coronal, sagittal, and lambdoid sutures, as well as turribrachycephaly.
Crouzon syndrome: Associated findings
Craniosynostosis involving the coronal, sagittal, and lambdoid sutures, as well as turribrachycephaly. Other findings includemid face hypoplasia, exorbitism, and proptosis. The extremities are normal.
Goldenhar syndrome: Overview
Goldenhar syndrome, or oculoauriculovertebral dysplasia, involves asymmetry of the hard and soft tissues of the face.
Goldenhar syndrome: Laterality
This condition is most commonly unilateral but may be seen bilaterally in some patients.
Goldenhar syndrome: Manifestations
Manifestations of this syndrome include hypoplasia involving the mandible and underlying soft tissues of the face, epibulbar dermoids, and varied degrees of microtia on the affected side. Most patients have associated vertebral abnormalities.
Nager syndrome:
Characterized by craniofacial and upper extremity abnormalities:
Hypoplasia of the orbits, zygoma, maxilla, mandible, and soft palate. Auricular defects may also be present. Hypoplasia or agenesis occurs in the radius, thumbs, and metacarpals. Some patients may have radioulnar synostosis and elbow joint deformities.
Treacher Collins syndrome:
Patients with Treacher Collins syndrome, or mandibular dysostosis, have hypoplasia of the zygoma, maxilla, and mandible, downward slanting of the palpebral fissures, colobomas of the lower eyelids, absence of eyelashes, and auricular defects.
Nager syndrome: Heredity
Autosomal recessive
A 66-year-old man comes for a follow-up examination 7 months after resection of a T4 N1 M0 squamous cell carcinoma in the region of the retromolar trigone, including alveolectomy, followed by soft-tissue reconstruction with a platysma flap. Postoperatively, he received radiation therapy to the primary tumor site (6 Gy) and to the neck bilaterally (64 Gy). He completed radiation therapy 5 months ago. Examination today shows a malodorous, tender area of exposed, soft bone at the operative site. A panoramic x-ray study (Panorex) is shown. Multiple biopsies are negative for recurrent carcinoma. Which of the following is the most appropriate management?
A ) Long-term intravenous antibiotic therapy
B ) Open reduction and internal fixation
C ) Segmental resection and vascularized tissue transfer
D ) Sequestrectomy
C ) Segmental resection and vascularized tissue transfer
The patient described has osteoradionecrosis of the mandible, a complication that occurs in up to 40% of patients receiving adjuvant radiation therapy for head and neck malignancies. When more extensive destruction of the mandible is present, or when there is a pathologic fracture, as seen in the scenario described, resection of all the necrotic bone and soft tissue is indicated, followed by reconstruction with vascularized bone and soft tissue. Successful healing occurs in up to 80 to 90% of patients with more extensive disease when treated in this way.
Osteoradionecrosis of the jaw occurs in up to 40% of patients receiving adjuvant radiation therapy for head and neck malignancies
Osteoradionecrosis occurs in up to 40% of patients receiving adjuvant radiation therapy for head and neck malignancies
Osteoradionecrosis of the jaw occurs due to:
Hypoxia, hypovascularity, hypocellularity, and impaired collagen synthesis.
Definition of osteoradionecrosis
The traditional definition is an area of exposed, irradiated bone that is nonhealing over 3 months.
Osteoradionecrosis of the jaw: Management
- Osteoradionecrosis limited to the alveolar ridge or mandible superior to the alveolar canal: Debridement and antibiotic therapy, plus or minus hyperbaric oxygen therapy, with soft-tissue reconstruction as needed
- When more extensive destruction of the mandible is present, or when there is a pathologic fracture:
Resection of all the necrotic bone and soft tissue is indicated, followed by reconstruction with vascularized bone and soft tissue.
Osteoradionecrosis of the jaw: Successful treatment in ____ patients with severe disease treated with resection and reconstruction with vascularized bone and soft tissue
Successful healing occurs in up to 80 to 90% of patients with more extensive disease when treated in this way.
Osteoradionecrosis of the jaw: Local flaps
Local flaps are of limited use for soft-tissue coverage because of the radiation. (RT to the neck)
A 40-year-old woman is referred for treatment after being found to have an idiopathic fracture on panoramic radiograph (Panorex), performed because of severe pain following a dental procedure. She has been treated for osteopenia related to multiple myeloma. A CT is shown. On evaluation, the patient has chronic pain and exposed intraoral bone. Which of the following is the most likely diagnosis?
A ) Bisphosphonate-related osteonecrosis
B ) Breast cancer metastasis
C ) Infectious osteomyelitis
D ) Myeloma-induced changes to the mandible
E ) Old unhealed fracture from trauma
A ) Bisphosphonate-related osteonecrosis
Bisphosphonates are routinely prescribed in the practice of medical oncology, and the incidence in these patients for BRON ranges between 1% and 10%. Becauseof the common use of these drugs in multiple myeloma, there have been many case reports of patients with BRON.
Bisphosphonates and relevance to malignancy
Bisphosphonates are clinically important for the treatment of hypercalcemia of malignancy and can reduce cancer-induced bone pain.
Frequency of bisphosphonate related osteonecrosis in patient receiving this medication for cancer
Ranges between 1%-10%.
A 32-year-old man comes to the emergency department because hehas had jaw pain and difficulty closing his mouth after he was punched in the face 30 minutes ago. A panoramic radiograph (Panorex- right mandibular angle fracture) of the lower face is shown. Which of the following clinical findings is consistent with this fracture pattern? A ) Anteriorcrossbite B ) Fracture of tooth No. 31 C ) Maxillary occlusal cant D ) Paresthesia of right upper lip E ) Posterior open bite on the left
E ) Posterior open bite on the left
A right mandibular angle fracture is shown. Foreshortening of the height on the right from the fracture and powerful influence of the masseter will likely result in posterior open biteon the contralateral side. Anterior crossbite occurs in maxillary hypoplasia and prognathism conditions and is not a result of the fracture in the patient described. Standard numbering of the dentition of the maxillary dental arch from right to left is No. 1 to No. 16. The mandibular dental arch from left to right is No. 17 through No. 32. Maxillary occlusal cant occurs congenitally or with maxillary fracture.Paresthesias of the upper lip are not associated with mandibular fracture through the inferior alveolar nerve. This fracture would be consistent with paresthesia of the right lower lip.
Standard numbering of the dentition
Maxillary dental arch from right to left is No. 1 to No. 16.
Mandibular dental arch from left to right is No. 17 through No. 32.
A 56-year-old woman with type 1 diabetes mellitus has a six-month history of a slowly enlarging, painless mass in the mandible. She is edentulous. Physical examination shows a 4-cm mass on both the buccal and lingual portions of the alveolus with intact mucosa. A panoramic radiograph (Panorex) is shown. Biopsy confirms ameloblastoma. Which of the following is the most definitive management?
A ) Conservative segmental resection of the mandible, followed by nonvascularized iliac crest cortical bone grafting
B ) Curettage and cancellous bone grafting
C ) Segmental resection of the mandible with wide margins and cervical lymph node dissection, followed by vascularized free fibular bone grafting
D ) Segmental resection of the mandible with wide margins and cervical lymph nodedissection, followed by vascularized free fibular bone grafting and adjuvant radiation therapy
E ) Segmental resection of the mandible with wide margins, followed by vascularized free fibular bone grafting
E ) Segmental resection of the mandible with wide margins, followed by vascularized free fibular bone grafting
The history and radiographic findings in the patient described are most consistent with multicystic ameloblastoma. This odontogenic tumor commonly presents as a painless enlarging mass in the mandible or, less commonly, in the maxilla. The typical radiographic finding is a multilocular lucency with preservation of the cortex, though the cortex may be thinned.
Extraosseous lesions may have no radiographic findings. This tumor goes beyond the boundaries seen on radiograph.
Wide resection is necessary for multicystic lesions to prevent recurrence. The sizeable defect resulting from wide resection in the patient described would be best treated with vascularized bone graft, especially in light of her diabetes.
The lack of mucosal ulceration or cortical bone erosion in a lesion this size point away from a malignancy; therefore, cervical lymph node dissection and adjuvant radiation therapy would not be indicated.
Multicystic ameloblastoma: clinical presentation
This odontogenic tumor commonly presents as a painless enlarging mass in the mandible or, less commonly, in the maxilla.
Multicystic ameloblastoma: Radiographic findings
The typical radiographic finding is a multilocular lucency with preservation of the cortex, though the cortex may be thinned.
Extraosseous lesions may have no radiographic findings. This tumor goes beyond the boundaries seen on radiograph.
Multicystic ameloblastoma: Management
Wide resection is necessary for multicystic lesions to prevent recurrence.
Curettage or conservative resection of a multi cystic tumor would result in recurrence in 50% of patients. Conservative resection may have higher cure rates for unicystic lesions.
A 5-year-old girl is brought to the emergency department immediately after falling from a swing set and hitting her chin on the cement pavement. Physical examination shows a laceration of the chin and an anterior open bite. Radiographs show bilateral subcondylar fractures with medial displacement of the right condylar neck and comminution of the left condylar head. A good dental relation is established while using anesthesia. Which of the following is the most appropriate management?
A ) Intermaxillary fixation for one to two weeks
B ) Intermaxillary fixation for four to six weeks
C ) Open reduction and internal fixation of the right and left fractures followed by early range of motion exercises
D ) Open reduction and internal fixation of the right subcondylar fracture followed by intermaxillary fixation for one to two weeks
E ) Open reduction and internal fixation of the right subcondylar fracture followed by intermaxillary fixation for four to six weeks
A ) Intermaxillary fixation for one to two weeks
Because the condylar head is not displaced in the patient described, open reduction and internal fixation of the right subcondylar fracture is not indicated. Intermaxillary fixation should be applied and remain in place for one to two weeks after the surgery. Subsequently, active and passive physical therapy of the mandible should be performed to work the mandible and remold the subcondylar union. This is especially important because of the comminuted intracapsular fracture on the contralateral side. Intermaxillary fixation applied for an extended period (greater than four weeks) may result in postoperative ankylosis. This is very difficult to treat. Releasing the intermaxillary fixation at two weeks may cause a delayed crossbite or anterior open bite. Both may be treated secondarily with a sagittal split osteotomy
Typically, open reduction of a fracture of the mandibular condyle:
Open reduction of a fracture of the mandibular condyle is not commonly performed because the procedure may be complicated, and closed reduction is usually sufficient.
Open reduction of the condyle is indicated in what situations?
Open reduction of the condyle is indicated in the following four situations:
•Displacement into the middle cranial fossa
•Impossibility of obtaining adequate dental occlusion by closed reduction
•Lateral extracapsular displacement of the condyle
•Invasion by a foreign body (eg, a bullet from a gunshot wound)
A patient with bilateral displaced subcondylar fractures is most likely to have which of the following occlusal patterns? A ) Anterior crossbite B ) Anterior open bite C ) Posterior crossbite D ) Posterior open bite
B ) Anterior open bite
When a patient sustains a bilateral subcondylar fracture, there is the possibility of shortening of the posterior mandibular height. This shortening is secondary to telescoping of the condylar fragments and muscular pull of the boney components.
A premature occlusal contact of the posterior occlusion occurs, resulting in an anterior open bite.
A 6-year-old boy is evaluated because of severe pain on opening his mouth. One week ago, he hit his chin in a fall. Physical examination shows chin deviation to the right and premature contact of the molar region on the right. Facial radiographs are ordered. The most likely cause of these findings is fracture of which of the following segments of the mandible? (A)Angle (B)Body (C)Condyle (D)Ramus (E)Symphysis
(C)Condyle
Mandibular condyle fractures are the most common facial fractures seen in children. In a recent review of more than 1250 pediatric maxillofacial fractures, condylar injuries constituted 34.9% of all mandible fractures; however, the angle (17.7%), body (14.9%), ramus (8%), and symphysis (9%) are also important sites of potential mandible fracture.
Most common pediatric facial fracture:
Mandibular
Most common sites of mandibular fracture in children
35%: Condylar
18%: Angle
15%: Body
8%: Ramus
Which of the following regions of the adult mandible has the highest incidence of fracture? (A)Angle (B)Body (C)Coronoid (D)Ramus (E)Symphysis
(A)Angle
The angle of the mandible has the highest incidence of fracture—up to 30%. Incidence of fracture is 15% to 20% for the body and parasymphysis. The presence of an isolated symphyseal or parasymphyseal fracture should alert the surgeon to the possibility of a second fracture near the angle.
Most common sites of mandibular fracture in adults
30%: Angle
20%: Parasymphysis
15%: Body
The presence of an isolated symphyseal or parasymphyseal fracture should alert the surgeon to the possibility of:
The presence of an isolated symphyseal or parasymphyseal fracture should alert the surgeon to the possibility of a second fracture near the angle.
Which of the following muscles controls depression and protrusion of the mandible? (A)Buccinator (B)Digastric (C)Lateral pterygoid (D)Masseter (E)Temporalis
(C)Lateral pterygoid
The lateral pterygoid muscle originates from the greater wing of the sphenoid, the inferotemporal crest, and the lateral pterygoid plate and inserts on the neck of the mandibular condyle and articular disc of the temporomandibular joint.
Its action is to depress, protrude, and move the mandible from side to side.
The muscles of mastication are all inserted upon the ________ and innervated by:
The muscles of mastication are all inserted upon the mandible and innervated by the mandibular division of the trigeminal (V) nerve
Anatomy of the lateral pterygoid muscle
The lateral pterygoid muscle originates from the greater wing of the sphenoid, the inferotemporal crest, and the lateral pterygoid plate and inserts on the neck of the mandibular condyle and articular disc of the temporomandibular joint.
Action of the lateral pterygoid muscle
Its action is to depress, protrude, and move the mandible from side to side.
Anatomy of the masseter
The masseter muscle originates from the zygomatic arch and inserts on the mandibular angle, ramus, and condyle.
Action of the masseter
Its action is to close the jaw.
Anatomy of the medial pterygoid muscle
The medial pterygoid muscle originates on the medial aspect of the lateral pterygoid plate of the sphenoid in the tuberosity of the maxilla. It inserts on the medial surface of the ramus of the mandible.
Action of the medial pterygoid muscle
Acts to close the jaw.
Anatomy of the temporalis muscle
The temporalis muscle originates from the temporal fascia and entire temporal fossa. It inserts on the coronoid process and the anterior border of the ramus of the mandible
Action of the temporalis muscle
Acts to close and retract the jaw.
Innervation of the buccinator muscle
The buccinator muscle is innervated by the facial nerve (VII).
A 20-year-old man comes to the office for consultation regarding malocclusion. On physical examination, the mandibular incisors are anterior to the maxillary incisors. The mesial buccal cusp of the maxillary first molar lies distal to the buccal groove of the mandibular first molar. These findings are characteristic of which of the following Angle classifications? (A)Angle class I (B)Angle class II, division I (C)Angle class II, division II (D)Angle class III
(D)Angle class III
Angle class I, or normal occlusion, is characterized as having the mesial buccal cusp of the upper first molar occluding in the buccal groove of the mandibular first molar. In Angle class II, both divisions I and II, the mandibular dentition is distal to its class I position. Class II, division 1 is lingually inclined, and Class II, division 2 is labially inclined. In Angle class III malocclusion, the mandibular molar is anterior to its normal position with the maxillary molar.
Angle class I
Angle class I, or normal occlusion, is characterized as having the mesial buccal cusp of the upper first molar occluding in the buccal groove of the mandibular first molar.
Angle class II
In Angle class II, both divisions I and II, the mandibular dentition is distal to its class I position.
Angle class II, division 1
Class II, division 1 is lingually inclined, and
Angle class II, division 2
Class II, division 2 is labially inclined.
Angle class III
In Angle class III malocclusion, the mandibular molar is anterior to its normal position with the maxillary molar.
A 46-year-old man comes to the office because he has pain in the jaw and trismus after being involved in a motor vehicle collision two days ago. Radiographs show a mandibular fracture. In adults, the normal range of vertical mandibular opening is closest to which of the following? (A)11 to 20 mm (B)21 to 30 mm (C)31 to 40 mm (D)41 to 50 mm (E)51 to 60 mm
(D)41 to 50 mm
In adults, the vertical mandibular opening measured from maxillary incisal edge to mandibular incisal edge (interincisal distance) typically ranges from 40 to 50 mm. In addition, normal range of motion of the mandible includes lateral jaw excursion (measured at the midline incisor) to 10 mm on each side.
Decreased mandibular opening may indicate dysfunction of the temporomandibular joint (TMJ) or surrounding soft tissues. Patients who may potentially have internal derangement of the TMJ also may experience painless clicking when opening the mouth.
In adults, the vertical mandibular opening measured from maxillary incisal edge to mandibular incisal edge (interincisal distance) typically ranges from:
In adults, the vertical mandibular opening measured from maxillary incisal edge to mandibular incisal edge (interincisal distance) typically ranges from 40 to 50 mm.
In addition, normal range of motion of the mandible includes lateral jaw excursion to:
In addition, normal range of motion of the mandible includes lateral jaw excursion (measured at the midline incisor) to 10 mm on each side.
Dysfunction of the temporomandibular joint
Decreased mandibular opening may indicate dysfunction of the temporomandibular joint (TMJ) or surrounding soft tissues. Patients who may potentially have internal derangement of the TMJ also may experience painless clicking when opening the mouth.
For normal range of motion of the mandible, lateral jaw excursion is measured at:
Measured at the midline incisor
In planning open reduction and internal fixation in a patient with a low subcondylar neck fracture, which of the following extraoral incisions provides the safest and most versatile exposure to thefracture site? (A) Postauricular (B) Preauricular (C) Retromandibular (D) Submandibular
(C) Retromandibular
The retromandibular incision provides the safest and most versatile exposure for open reduction and internal fixation of submandibular fractures. When compared with the subcondylar and preauricular incisions, there is significantly less injury to the marginal mandibular, temporal, and zygomatic branches of the facial nerve.
The retromandibular incision allows access superiorly to the coronoid notch and inferiorly to the angle of the mandible. The addition of a transfacial trocar to this approach facilitates access to higher level subcondylar fractures as well. The preauricular, postauricular, and submandibular incisions provide a more limited view of low subcondylar fractures.
Which incision provides the safest and most versatile exposure for open reduction and internal fixation of submandibular fractures?
The retromandibular incision provides the safest and most versatile exposure for open reduction and internal fixation of submandibular fractures.
Retromandibular incision versus subcondylar and preauricular incision: morbidity
When compared with the subcondylar and preauricular incisions, with a retromandibular incision there is significantly less injury to the marginal mandibular, temporal, and zygomatic branches of the facial nerve.
The retromandibular incision allows access to:
The retromandibular incision allows access superiorly to the coronoid notch and inferiorly to the angle of the mandible.
With the addition of a transfacial tracer, the retromandibular incision allows access to:
The retromandibular incision allows access superiorly to the coronoid notch and inferiorly to the angle of the mandible. The addition of a transfacial trocar to this approach facilitates access to higher level subcondylar fractures as well.
A 5-year-old child has malocclusion and limited opening of the mouth after falling from playground equipment. A CT scan is shown. Which of the following is the most likely long-term sequela of this patient’s injury? (A) Bimaxillary prognathism (B) Mandibular hypoplasia (C) Mandibular prognathism (D) Maxillary hypoplasia (E) Maxillary prognathism
(B) Mandibular hypoplasia
This child is at increased risk for mandibular hypoplasia. The condyle serves as a growth center for the mandible and contributes primarily to vertical growth. The condylar cartilage is a site of secondary passive growth dependent on forces acting on it, notably the medial and lateral pterygoid muscles. Pediatric condylar fractures generally remodel and do not often cause growth disturbance. However, the thin, localized functional matrix of the condyle may disallow normal mandibular growth after it has been injured and may result in unilateral or bilateral hypoplasia depending on the injury. Pediatric mandibular fractures are frequently treated conservatively via closed reduction and short periods of maxillomandibular fixation.
Growth center for the mandible
The condyle serves as a growth center for the mandible and contributes primarily to vertical growth. The condylar cartilage is a site of secondary passive growth dependent on forces acting on it, notably the medial and lateral pterygoid muscles.
Growth after a pediatric condylar fracture
Pediatric condylar fractures generally remodel and do not often cause growth disturbance. However, the thin, localized functional matrix of the condyle may disallow normal mandibular growth after it has been injured and may result in unilateral or bilateral hypoplasia depending on the injury.
A 12-year-old boy is brought to the emergency department after he fell while riding his bike and landed on the chin. Panorex radiographs show a minimally displaced fracture of the high right condylar neck and an open left parasymphyseal fracture. Which of the following is the most effective management?
(A) Observation with serial radiographs and restriction to soft diet
(B) Intermaxillary fixation with infraorbital and circummandibular wires for four weeks
(C) Intermaxillary fixation with arch bars for four weeks
(D) Open reduction with internal fixation of the parasymphyseal fracture and arch bars for two weeks
(E) Open reduction with internal fixation of both the parasymphyseal fracture and the fracture of the high condylar neck
(D) Open reduction with internal fixation of the parasymphyseal fracture and arch bars for two weeks
Observation alone is inadequate management of the parasymphyseal fracture. This child presents in the late phase of the mixed dentition and should have enough adult dentition in place to secure the arch bars. Wires to reduce the fractures will not provide as much stability as arch bars. This technique, however, is useful in the child who does not yet have enough adult dentition to secure the arch bars.
Immobilization for a short period (i.e., two weeks) is the appropriate management of the condylar neck fracture. This will help to allow the fractures to become stable enough to maintain the reduction once movement is instituted. Early movement helps to decrease the risk of ankylosis of the temporal mandibular joint.
Open reduction and internal fixation (ORIF) of the parasymphyseal fracture will ensure an anatomic reduction of a stable skeletal unit. This, in turn, will decrease the risk of infection and nonunion
Using wires instead of arch bars in a pediatric patient
Wires to reduce the fractures will not provide as much stability as arch bars. This technique, however, is useful in the child who does not yet have enough adult dentition to secure the arch bars.
Management of a condylar neck fracture
Immobilization for a short period (i.e., two weeks) is the appropriate management of the condylar neck fracture. This will help to allow the fractures to become stable enough to maintain the reduction once movement is instituted. Early movement helps to decrease the risk of ankylosis of the temporal mandibular joint.
A 22-year-old man sustains a left subcondylar fracture of the mandible during a motor vehicle collision. On CT scan, the condyle is displaced medially and anteriorly. This displacement is most likely caused by tension from which of the following muscles? (A) Medial pterygoid (B) Lateral pterygoid (C) Masseter (D) Mylohyoid (E) Temporalis
(B) Lateral pterygoid
The inferior belly of the lateral pterygoid originates from the lateral pterygoid plate and inserts onto the scaphoid fossa of the condyle and joint capsule. The superior belly of the lateral pterygoid muscle originates from the sphenoid and inserts on the temporomandibular joint. The effect of the lateral pterygoid muscle is to displace the condyle medially and anteriorly in fractures of the condylar neck. It also tends to displace the meniscus anteriorly.
The mylohyoid muscle displaces segmental body fractures in what direction?
The mylohyoid muscle inserts on the body of the mandible, displacing segmental body fractures medially.
The effect of the lateral pterygoid muscle is to displace fractures of the condylar neck in what direction?
The effect of the lateral pterygoid muscle is to displace the condyle medially and anteriorly in fractures of the condylar neck. It also tends to displace the meniscus anteriorly.
A 22-year-old man sustains a transverse, noncomminuted fracture of the right mandibular angle when he is struck in the face during a fistfight. Which of the following interventions best adheres to Champy’s principle for management of this fracture?
(A) Dynamic compression plate with bicortical screws on the inferior edge of the mandible and a superior tension band
(B) Dynamic compression plate with bicortical screws and a mandibular arch bar
(C) Lag screw
(D) Miniplate with monocortical screws along the external oblique ridge
(E) Reconstruction plate with bicortical screws
(D) Miniplate with monocortical screws along the external oblique ridge
Champy’s principles for fracture management call for placement of miniplates along the lines of tension in the mandible at the site of the fracture. Because compression is not necessary, the miniplates can be anchored with monocortical screws. Based on the muscular forces pulling on the mandible, Champy determined that, anterior to the canine tooth, two miniplates are needed to control the rotational forces of the genial and digastric muscles;posterior to the canine tooth, just one miniplate is required.
In a 10-year review examining various methods for treating fractures of the mandibular angle, Ellis concluded that use of a single 2.0-mm noncompression miniplate was associated with fewer complications than a double-plate system (one using two compression or noncompression plates) or a reconstruction plate.
Champy’s principles for fracture management call for placement of miniplates where?
Champy’s principles for fracture management call for placement of miniplates along the lines of tension in the mandible at the site of the fracture.
Champy: When are one versus two miniplates required?
Based on the muscular forces pulling on the mandible, Champy determined that, anterior to the canine tooth, two miniplates are needed to control the rotational forces of the genial and digastric muscles; posterior to the canine tooth, just one miniplate is required.
Fractures of the mandibular angle: One versus two plates
In a 10-year review examining various methods for treating fractures of the mandibular angle, Ellis concluded that use of a single 2.0-mm noncompression miniplate was associated with fewer complications than a double-plate system (one using two compression or noncompression plates) or a reconstruction plate.
A 26-year-old man comes to the office because he has pain in the mandible seven days after undergoing open reduction and internal fixation of a fracture of the mandible. Physical examination shows infection in the submandibular space. Which of the following teeth are the most likely source of this infection?
(A) Mandibular canines
(B) Mandibular central incisors
(C) Mandibular first and second premolars
(D) Mandibular second and third molars
(E) Maxillary second and third molars
(D) Mandibular second and third molars
The submandibular space is located inferolateral to the mylohyoid muscle and superior to the hyoid bone. The contents of the submandibular space include the submandibular gland, lymph nodes, the facial vein and artery, and the inferior loop of the hypoglossal (XII) nerve. Anteriorly, the submandibular space communicates with the submental space and posteriorly with the pharyngeal space. The sublingual space is located superomedial to the mylohyoid muscle. Involvement of the submandibular space is produced principally by infections of the second and third mandibular molars because of the more superior position of the mylohyoid ridge on the mandible posteriorly, which places the root apices of the second and third molars beneath the mylohyoid muscle. Infections of the maxillary molars, when they extend through the buccal cortical plates above the attachments of the buccinator muscle, can present as infections of the buccal space. Infections from the anterior mandibular teeth (anterior to the second molar) usually drain above the mylohyoid muscle into the sublingual space.
The submandibular space
The submandibular space is located inferolateral to the mylohyoid muscle and superior to the hyoid bone.
Contents of the submandibular space
The contents of the submandibular space include the submandibular gland, lymph nodes, the facial vein and artery, and the inferior loop of the hypoglossal (XII) nerve.
The submandibular space communicates with?
Anteriorly, the submandibular space communicates with the submental space and posteriorly with the pharyngeal space.
Location of the sublingual space
The sublingual space is located superomedial to the mylohyoid muscle
How are infections of the submandibular space produced?
Involvement of the submandibular space is produced principally by infections of the second and third mandibular molars because of the more superior position of the mylohyoid ridge on the mandible posteriorly, which places the root apices of the second and third molars beneath the mylohyoid muscle.
Extension of infections of the maxillary molars
Infections of the maxillary molars, when they extend through the buccal cortical plates above the attachments of the buccinator muscle, can present as infections of the buccal space.
Extension of infections from the anterior mandibular teeth
Infections from the anterior mandibular teeth (anterior to the second molar) usually drain above the mylohyoid muscle into the sublingual space.
The application of a locking reconstruction plate to a comminuted mandibular fracture is LEAST likely to cause which of the following?
(A) Decreased bone resorption
(B) More difficulty in contouring the plate
(C) Hardware failure
(D) Hardware-related infection
(E) Malocclusion
(E) Malocclusion
Use of a locking reconstruction bone plate has been shown to decrease postoperative malocclusion after a comminuted fracture of the mandible. A conventional (nonlocking) bone plate requires precise adaptation of the plate to the underlying bone. Without intimate contact, the bone is drawn toward the plate when the screws are tightened, altering the position of the osseous segments and the occlusal relationship. However, a locking bone plate does not require intimate contact of plate to bone because the bony segments are secured by screws that are locked to the plate. This makes it less likely for screw insertion to alter the reduction and, ultimately, the occlusion.
A conventional plate is also called a:
A conventional plate is a nonlocking plate
A conventional plate requires what positioning relative to the bone?
A conventional (nonlocking) bone plate requires precise adaptation of the plate to the underlying bone
What happens if a conventional plate is not precisely adapted to the underling bone?
Without intimate contact, for a conventional/nonlocking plate, the bone is drawn toward the plate when the screws are tightened, altering the position of the osseous segments and the occlusal relationship.
Positioning of a locking vs nonlocking plate vs the bone
Conventional/nonlocking plate requires precise adaptation of the plate to the underlying bone
A locking plate does not require intimate contact of the palte to the bone
Why doesn’t a nonlocking plate require precise positioning of the plate vs the bone?
A locking bone plate does not require intimate contact of plate to bone because the bony segments are secured by screws that are locked to the plate.
