13 Odontogenic Disorders

Question 1

1 What germ layers and which branchial arch give rise to the teeth?

Answer 1

• Ectoderm
• First branchial arch as well as ectomesenchyme from the neural crest and mesoderm

Question 2

2 Name the muscles of mastication.

Answer 2

• Masseter muscle
• Medial pterygoid muscle
• Lateral pterygoid muscle
• Temporalis muscle

Question 3

3 Name the teeth from lateral to medial.

Answer 3

• Molars: Third (wisdom tooth), second, first
• Premolars: Second bicuspid/premolar, first bicuspid/ premolar
• Canines: Cuspid
• Incisors: Lateral incisor, central incisor

Question 4

4 Number the teeth according to the universal numbering system. (▶ Fig. 13.1)

Answer 4

Count maxillary teeth from right to left:

• No. 1: Right maxillary third molar
• No. 16: Left maxillary third molar
• No. 17: Mandibular left third molar
• No. 32: Mandibular right third molar

Question 5

5 Name the origin, insertion, and function of the lateral pterygoid muscle.

Answer 5

• Origin: Superior head, greater wing of sphenoid; inferior head, lateral aspect of lateral pterygoid plate
• Insertion: Superior head, articular disk; inferior head, condylar neck
• Function: Opens and protrudes jaw

Question 6

6 Name the main components of the temporomandibular joint (TMJ) within the joint capsule from superior to inferior. (▶ Fig. 13.2)

Answer 6

1. Glenoid fossa
2. Superior joint space
3. Articular disk
4. Inferior joint space
5. Head of mandibular condyle

Question 7

7 Describe the various surfaces of the teeth. (▶ Fig. 13.3)

Answer 7

• Mesial: Toward the midline
• Distal: Away from the midline
• Facial: Toward the cheek or lips
• Labial: Toward the lips (anterior teeth)
• Buccal: Toward the cheeks (posterior teeth)
• Lingual: Toward the tongue
• Incisal: Toward the biting surface (anterior teeth)
• Occlusal: Toward the biting surface (posterior teeth)
• Apical: Toward the apex or tip of the root

Question 8

8 Describe the sensory innervation to the TMJ.

Answer 8

The masseteric, deep temporal, and auriculotemporal nerves (all branches of cranial nerve [CN] V3) supply the joint capsule.

Question 9

9 What are the three main layers of a tooth? (▶ Fig. 13.4)

Answer 9

• Enamel
• Dentin
• Dental pulp

Question 10

10 What are the functions of the posterior teeth?

Answer 10

The premolars and molars grind food as well as establish a vertical dimension of occlusion.

Question 11

11 What are bone morphogenic proteins (BMPs)?

Answer 11

Proteins that are osteoinductive and are instrumental in regulating bone and cartilage development and formation

Question 12

12 Describe the Angle classification of dental relationships. (▶ Fig. 13.5)

Answer 12

• Class I: Normal occlusion, mesiobuccal cusp of the maxillary first molar aligns with the buccal groove of the mandibular first molar
• Class II: Distoclusion (retrognathism), mesiobuccal cusp of the maxillary first molar mesial to the buccal groove
• Class III: Mesioclusion (prognathism), mesiobuccal cusp of the maxillary first molar distal to the buccal groove

Question 13

13 Describe the evaluation of a panoramic radiograph (orthopanotomogram).

Answer 13

Evaluation should include the teeth and any evidence of dental caries or periapical pathology, the alveolar and basal bone of the jaws, the inferior alveolar nerve canal, ramus and condyles, and maxillary sinuses; account for any impacted or missing/supernumerary teeth.

Question 14

14 Describe the radiologic findings common to benign odontogenic tumors.

Answer 14

Common findings include radiolucency, often multilocular, and a propensity to expand the cortical boundaries of the jaw and push the inferior alveolar nerve inferiorly. Cortical margins are typically intact. Teeth may be displaced or roots resorbed (more aggressive malignancy will often show the whole root and a “tooth floating in space”).

Question 15

15 Which anatomical regions are best visualized by standard dental X-rays?

Answer 15

Tooth-bearing regions of the maxilla and mandible are well demonstrated by dental films; the ramus, condylar region, and inferior aspect of the mandible are usually missed by most dental films (periapical and bitewing films). Panoramic radiographs show the jaws and the condyle more completely, but they are less accurate in diagnosing dental disease. Panorex is often distorted in the midline.

Question 16

16 Describe the causes of osteoradionecrosis (ORN) of the mandible.

Answer 16

Radiation therapy results in endarteritis and fibrosis with resulting tissue becoming hypocellular, hypovascular, and hypoxic. ORN may develop spontaneously or even after minor trauma. Typical radiation thresholds for risk are 50 to 60 Gy.

Question 17

17 How long after radiation does ORN typically develop?

Answer 17

Onset is bimodal and peaks at both 3 months and 5 years after radiation. It can occur as early as 2 months and as late as 15 years.

Question 18

18 What are some signs and symptoms of mandibular ORN?

Answer 18

Deep bone pain, exposed bone with or without superinfection, trismus, fistula, halitosis, dysgeusia, pathologic fracture, paresthesia, anesthesia, and edema

Question 19

19 What is the mechanism of bisphosphonate-related osteonecrosis of the mandible?

Answer 19

Bisphosphonates downregulate osteoclast function, resulting in impaired bone turnover and bone repair. They have also been found to inhibit angiogenesis. After even minor dentoalveolar trauma, affected bone has a limited capacity to heal and may develop osteonecrosis. Intravenous (IV) bisphosphonate use results in a significantly higher risk for development of osteonecrosis of the jaw.

Question 20

20 Name the two descriptive categories of TMJ disorders. Which is most common?

Answer 20

Extra-articular disorders and intra-articular disorders. Extraarticular disorders are far more common.

Question 21

21 Contrast the findings in TMJ osteoarthritis and TMJ synovitis.

Answer 21

Osteoarthritis is a degenerative disease in the TMJ, as it is in other joints in the body. It is caused by a loss of articulating tissues and can be described as a mechanical, noninflammatory disease with bone-on-bone contact.

By contrast, TMJ synovitis is definable by its inflammatory nature. Inflammatory mediators may accumulate secondary to trauma, disk malfunction, or parafunctional habits.

Question 22

22 What is the best imaging modality for the TMJ?

Answer 22

Disk displacement and internal derangement of the TMJ are best imaged using MRI. Bony diseases such as ankylosis or degenerative joint disease are best evaluated using CT. Panorex may be used as to screen for fracture, condylar resorption, or large pathology.

Question 23

23 How is TMJ internal derangement classified?

Answer 23

The Wilkes classification

• Stage 1: Asymptomatic, painless clicking; mild disk displacement with reduction
• Stage 2: Occasional painful clicking or locking; mild disk displacement and deformity
• Stage 3: Joint pain with functional changes (limited opening); nonreducing disk with deformity
• Stage 4: Chronic pain and functional deficit, degenerative osseous changes, and disk deformity
• Stage 5: End stage with crepitus, degenerative joint disease (DJD), and disk perforation or loss

Question 24

24 Name the two categories of TMJ disk displacement.

Answer 24

• Disk displacement with reduction (often heard as popping or clicking)
• Disk displacement without reduction (usually no associated noise)

Note: Often, displacement with reduction leads to displacement without reduction, which limits range of motion. This may be reversed with conservative therapy or with arthrocentesis or arthroscopy.

Question 25

25 In the case of anterior disk displacement with or without reduction, what are the indications for intervention?

Answer 25

Pain, impaired mobility (especially acute closed lock), joint locking, failure to respond to conservative therapy Asymptomatic joint noise is common (in up to 35% of Americans).

Question 26

26 How does osteoarthritis of the TMJ manifest?

Answer 26

Degenerative joint disease or arthritis of the TMJ most commonly affects the elderly population, but it can affect all ages.

Painful motion and joint loading are the hallmarks, along with CT findings of DJD. Myofascial pain symptoms must be ruled out. Unless related to ankylosis, it will not vastly reduce range of motion.

Question 27

27 What are the risk factors for septic TMJ arthritis?

Answer 27

• History of trauma, burn, surgery or dental work
• Systemic factors such as autoimmune disease, diabetes, immunosuppression, sexually transmitted infection, or prolonged steroid use

Question 28

28 What is the most common systemic inflammatory condition to affect the TMJ?

Answer 28

Rheumatoid arthritis. Traditional rheumatologic laboratory studies in addition to MRI are useful for establishing a diagnosis.

Question 29

29 What radiographic findings are expected in acute posttraumatic TMJ arthralgia?

Answer 29

Widening of the joint space might be seen, but radiographs may also be entirely normal.

Question 30

30 How should trismus be clinically evaluated in a patient with head and neck cancer who has undergone radiation?

Answer 30

Objectively measure the mouth opening (opening < 35 mm is generally considered restricted) and compare with subjective assessment of restriction as well as its effect on daily functions. Assess for pain on opening or other symptoms besides simple restriction of opening from fibrosis.

Question 31

31 What is the best initial therapy for postradiation trismus?

Answer 31

Stretching exercises, including insertion of stacked tongue blades or use of a commercial device such as Therabite. This requires multiple daily treatments over a period of months.

Question 32

32 How should ankylosis of the TMJ be managed?

Answer 32

Many algorithms have been described, but most include a description of resection of the ankylotic mass with ipsilateral coronoidectomy. Reconstruction is often with costochondral grafting, with or without an interpositional temporalis myofascial flap. Early and rigorous physiotherapy is imperative.

Question 33

33 Auriculocondylar syndrome is thought to develop from abnormalities in which branchial arches and which craniofacial bones are most commonly affected?

Answer 33

Known also as Goldenhar syndrome, hemifacial microsomia, and branchial arch syndrome, it affects the first and second branchial arches. There is high variability of expression and may affect the mandible, condyle, maxilla, zygoma, orbit, and temporal bones.

Question 34

34 Describe the clinical features of auriculocondylar syndrome.

Answer 34

• Auricular abnormalities (question-mark ear with constricted middle to lower thirds of the pinna, auricular cleft)
• TMJ/condylar abnormality (mandibular hypoplasia, condylar hypoplasia, or dysmorphism)
• Facial asymmetry with chin deviation toward the affected side
• Micrognathia
• Microstomia

Question 35

35 Describe the clinical features of mandibular condylar hypoplasia.

Answer 35

Usually unilateral with mandibular deviation toward the affected side and severe malocclusion.

Question 36

36 Define the condition of mandibular condylar hyperplasia.

Answer 36

• Excessive, progressive unilateral growth of mandibular condyle resulting in aesthetic and functional problems such as facial asymmetry, occlusal disturbance, and joint dysfunction
• Imaging must distinguish condylar hyperplasia from osteochondroma.
• Condylar hyperplasia may also be described in terms of hemimandibular hypertrophy and hemimandibular elongation

Question 37

37 How does bone single-photon emission CT scan aid in the diagnosis of mandibular condylar hyperplasia?

Answer 37

Technetium-99 radioisotope uptake is increased in the hyperplastic condyle, which is indicative of unilateral condylar activity. This is sensitive but nonspecific. Uptake is also increased with inflammation, infection, and neoplasia. Results should be interpreted along with clinical presentation.

Question 38

38 Define myogenous temporomandibular disorders.

Answer 38

Pain and dysfunction of the TMJ area that results from abnormal function or disease processes of the muscles of mastication. It is also known as masticatory myalgia and includes the following subtypes: myofascial pain, myositis, muscle spasm, and muscle contracture.

Question 39

39 What features characterize myofascial pain dysfunction syndrome (MPD)?

Answer 39

MPD is a dull, aching pain in the mandible, temple, or face that is associated with specific trigger points and can usually be reproduced by palpation of trigger points. Pain is typically located over the muscles of mastication or neck musculature rather than over the joint proper. MPD may be with or without concurrent intra-articular disease.

Question 40

40 What features characterize myositis of the masticatory musculature?

Answer 40

Diffuse, continuous pain over the entire muscle that may limit range of motion and cause swelling. Inflammation of the muscle is secondary to injury or infection, and pain worsens with muscle use.

Question 41

41 Describe the initial steps to treat masticatory myalgia.

Answer 41

Rest the jaws and muscles by adhering to the following: soft diet, avoiding caffeine, using heat or ice, take NSAIDs, avoid parafunctional habits, avoid sleeping on the stomach, and avoid excessive or prolonged jaw opening.

Question 42

42 How is a patient with complex myogenous masticatory pain treated after conservative measures have failed?

Answer 42

A pain clinic or pain team is most useful. Physical therapy, along with pharmacologic and lifestyle interventions, are helpful, as comprehensive treatment offers the best chances of success.

Question 43

43 What differentiates masticator muscle contracture from muscle contracture associated with masticator muscle spasm?

Answer 43

Chronicity. Masticator muscle contracture is a chronic condition with continued muscle shortening, whereas masticator muscle spasm is an acute condition that is often accompanied by pain.

Question 44

44 Describe lateral pterygoid spasm. (▶ Fig. 13.6)

Answer 44

• Acute, involuntary contracture of the lateral pterygoid muscle
• The muscle is shortened and produces decreased jaw mobility (often acute open lock) and accompanying localized pain.

Question 45

45 What differentiates myofascial pain dysfunction syndrome from fibromyalgia?

Answer 45

These may share underlying disease processes and are along the same spectrum. In general, fibromyalgia is notable for more diffuse muscle pain, greater association with sleep disorders, and depression. Myofascial pain is influenced more by regional factors (posture, parafunctional habits, trauma, etc.).

Question 46

46 What reconstructive options are available for TMJ arthroplasty?

Answer 46

The mainstay for modern arthroplasty is total and hemijoint prostheses. Autogenous grafts, such as costochondral grafts, may also be used. Gap arthroplasty may be augmented with a temporalis myofascial flap. Conchal cartilage has also been used as a disk replacement.

Question 47

47 How often is surgery indicated for disorders of the TMJ, and what are the absolute indications?

Answer 47

Only 5% of cases require surgical intervention. Absolute indications include treatment of neoplasia, joint ankylosis, or congenital/growth abnormalities that could alter maxillofacial growth.

Question 48

48 Name the different surgical interventions for TMJ disease.

Answer 48

Arthrocentesis, arthroscopy, modified condylotomy, and open joint surgery (including disk repair, repositioning, diskectomy, eminectomy, and joint replacement).

Question 49

49 A significant complication of open TMJ surgery is damage to the facial nerve. Which branch of the facial nerve is most commonly injured?

Answer 49

The temporal division of the facial nerve; temporary weakness is present in 5% of cases, and permanent weakness is reported in up to 1% of cases. Other complications include hemorrhage, occlusal changes, persistent change, heterotopic bone formation, and fibrous adhesion formation.

Question 50

50 What is the most common type of odontogenic cyst, and does it affect vital or nonvital teeth?

Answer 50

Periapical (radicular) cyst, which affects only nonvital teeth It is primarily the manifestation of a small chronic dental abscess.

Question 51

51 How does a lateral periodontal cyst differ from a periapical cyst?

Answer 51

Lateral periodontal cysts are developmental, arising from the epithelial rests of Serres or Malassez, and are most commonly found lateral to premolars and canines. Periapical cysts are found associated with any tooth and are found apically in the setting of chronic infection.

Question 52

52 What is the preferred management for the most common type of odontogenic inflammatory cyst?

Answer 52

• The most common type of odontogenic inflammatory cyst is a radicular or periapical cyst.
• Management may include extraction of the infected tooth and enucleation of the cyst. In many cases, root canal treatment may be indicated over extraction, depending on symptoms, chronicity, and prognosis of the tooth.

Question 53

53 What odontogenic cyst develops in the place of absent teeth?

Answer 53

• Primordial cysts, which are the rarest of all odontogenic cysts
• History is important in this instance to ensure that the tooth has not simply been removed at an earlier date, which would indicate a residual cyst or dentigerous cyst.

Question 54

54 Are dentigerous cysts associated with erupted or unerupted teeth, and where are they most likely to be found?

Answer 54

Unerupted or impacted teeth, found with:

Mandibular third molars > maxillary third molars > maxillary canines (in decreasing order of frequency)

Question 55

55 How common are dentigerous cysts, and what association do they have with odontogenic carcinoma?

Answer 55

Dentigerous cysts are the second most common odontogenic cysts. Up to 25% of odontogenic malignancies are thought to have transformed from an associated dentigerous cyst.

Question 56

56 How can botryoid odontogenic cysts be distinguished from lateral periodontal cysts?

Answer 56

Both cysts manifest preferentially in the same alveolar process locations (namely, the lateral surface of teeth, usually the mandibular premolar or canines). However, the botryoid cyst is multilocular, as its name indicates, and this is reflected histologically and radiographically. Botryoid cysts have a higher incidence of recurrence.

Question 57

57 What are the components of Gorlin syndrome (Gorlin-Goltz or basal cell nevus syndrome)? (▶ Fig. 13.7)

Answer 57

Diagnosis requires two major criteria or one major and two minor criteria.

Major criteria: (1) excessive basal cells or BCC earlier than age 20; (2) keratocystic odontogenic tumor when younger than 20; (3) palmar or plantar pitting; (4) lamellar calcification of the falx cerebri; (5) medulloblastoma, typically desmoplastic; (6) first-degree relative with basal cell nevus syndrome.

Minor components: (1) rib anomalies (e.g., bifid rib); (2) skeletal malformations and radiologic changes (i.e., vertebral anomalies, kyphoscoliosis, short fourth metacarpals, postaxial polydactyly); (3) macrocephaly; (4) cleft lip/palate; (5) ovarian/cardiac fibroma; (6) lymphomesenteric cysts; (7) ocular abnormalities (i.e., strabismus, hypertelorism, congenital cataracts, glaucoma, coloboma)

Question 58

58 Describe the manifestation of keratocystic odontogenic tumor.

Answer 58

Keratocystic odontogenic tumor occur in any jaw location, although they are most commonly noted in the posterior mandibular body and in the ramus. They are frequently noted in association with the crown of an unerupted tooth or near the tooth root. Recurrence is common (between 5 and 60%).

Question 59

59 What are the histologic features of a “ghost cell,” and with what odontogenic cyst is this most commonly associated?

Answer 59

Ghost cells are large, eosinophilic epithelial cells that lack a nucleus and are most commonly associated with calcifying odontogenic (or Gorlin) cysts. These ghost cells may later become calcified and may cause a foreign-body reaction that gives rise to the cyst. Ghost cells are also occasionally seen in odontomas, ameloblastic fibro-odontomas, and ameloblastomas.

Question 60

60 What is the preferred management for extraosseous calcifying odontogenic cysts (Gorlin cyst)?

Answer 60

Simple lesion removal. These cysts account for up to 25% of all Gorlin cysts and are often seen within the gingiva in patients in their sixth decade of life or later, and they are often seen in association with other odontogenic tumors.

Question 61

61 What is the preferred management for calcifying odontogenic cysts (Gorlin cysts)?

Answer 61

If the cyst is unilocular, enucleation is preferred. Multilocular lesions often require bony curettage.

Question 62

62 Describe the clinical features of glandular odontogenic cysts.

Answer 62

Rare and recently described, glandular odontogenic cysts (sialo-odontogenic cysts) may clinically resemble a low-grade central mucoepidermoid carcinoma. They appear anywhere in the jaw but favor the anterior regions. They may be multilocular with epithelial lining including eosinophilic columnar or cuboidal cells.

Question 63

63 What is the preferred management for an infant with an eruption cyst?

Answer 63

Expectant management; no intervention is necessary.

Question 64

64 What distinguishes a cyst from a pseudocyst?

Answer 64

Odontogenic cysts comprise an epithelial-lined pathologic cavity, usually fluid or semisolid filled. Pseudocysts lack epithelial lining.

Question 65

65 What are the clinical features of nasopalatine duct cysts, and in what gender and age of patient do they most often occur?

Answer 65

Nasopalatine duct cysts are classically well-circumscribed, heart-shaped, anterior midline palate masses. They are most commonly seen in men (twice as common as in women) and appear in the fourth to sixth decades.

Question 66

66 What are the clinical features of nasolabial cysts, and in what gender and age of patient do they most often occur?

Answer 66

These cysts manifest with painless swelling of the labial vestibule and/or nasal floor and are seen more commonly in women (three times as common as males) in the fifth decade of life.

Question 67

67 What is the favored management of traumatic bone cysts?

Answer 67

Surgical exploration. Traumatic bone cysts are more common in young patients, found primarily in the mandible, and are pseudocysts because they do not contain an epithelial lining. As such, there is nothing to excise surgically. However, by opening the cavity and inducing hemorrhage, surgical exploration induces granulation tissue formation, which resolves the lesion.

Question 68

68 What are Epstein pearls, what is their source, and how should they be managed?

Answer 68

Epstein pearls are midline palatal inclusion cysts of white/ yellow vesicles comprising rests of epithelial tissue trapped in the median raphe of the palate or the hard/soft palate junction. They are self-limited and require no intervention.

Question 69

69 What are Bohn nodules, what is their source, and how should they be managed?

Answer 69

Bohn nodules are round, whitish papules commonly found along the alveolar ridge in infants in their second to fourth months of life. The papules contain keratin, are more commonly found in the maxilla than the mandible, and are thought to arise from minor salivary glands. They are selflimited and require no intervention.

Question 70

70 What is pathophysiologic basis for Stafne bone cysts?

Answer 70

Stafne bone cysts are not true cysts but rather a depression in the lingual surface of the mandible. A pathognomonic finding is an ovoid radiolucency inferior to the inferior alveolar canal in the region of the second or third molar. Most often, this depression is filled with an accessory lobe of the submandibular gland, although adipose or lymphoid tissue may also be found.

Question 71

71 What clues at initial manifestation may signify increased concern for a malignant versus benign odontogenic tumor?

Answer 71

Pain, paresthesia, trismus, and rapid onset of malocclusion are associated with increased risk of malignancy.

Question 72

72 What are the important aspects of the history of a patient with a possible odontogenic mass?

Answer 72

Onset and duration/progression of the mass, complete dental history including any previous surgical intervention, erupted teeth, paresthesia, loose or displaced teeth, malocclusion, pain or absence thereof, trauma, and systemic symptoms

Question 73

73 What are the most common sites for odontogenic tumors?

Answer 73

Mandibular molars and maxillary cuspids

Question 74

74 Name the different types of odontogenic malignancies.

Answer 74

• Malignant ameloblastoma
• Ameloblastic carcinoma
• Primary intraosseous squamous cell carcinoma
• Clear cell odontogenic carcinoma
• Malignant calcifying epithelial odontogenic tumors
• Odontogenic ghost cell carcinoma
• Ameloblastic fibrosarcoma

Question 75

75 What are the most common sites of metastasis for malignant odontogenic tumors?

Answer 75

Lungs are most common, followed by regional lymph nodes.

Question 76

76 Describe the classification system for primary intraosseous carcinomas of the jaw presented by Elzay in 1982.

Answer 76

• Type I: Arising from exodontogenic cysts (e.g., squamous cell carcinoma)
• Type II: Odontogenic carcinomas (e.g., ameloblastic carcinoma)
• Type III: Arising de novo (e.g., squamous cell carcinoma)
• Type IV: Sarcomas (e.g., myoepithelial carcinoma)

Question 77

77 What is the recommended treatment for odontogenic malignancies?

Answer 77

Because of the extreme rarity of these cancers, no definitive diagnostic algorithm has been developed. In general, wide surgical excision is the treatment of choice

Question 78

78 How should a biopsy be undertaken for suspected intraosseous odontogenic tumors?

Answer 78

Depending on patient tolerance and anticipated procedure, anesthesia may be local only or any form of sedation or general anesthesia. Typically, mucosal incision takes place in an uninvolved area that can be easily closed. Aspiration is advised to rule out vascular lesions, after which safe entrance through the bone is undertaken. Specimens should include any areas of radiologic variation to ensure adequate sampling.

• Excisional biopsy is appropriate for cysts that are small and do not appear malignant on imaging.
• Incisional biopsy is warranted for larger lesions concerning for malignancy as a precursor to more definitive resection.

Question 79

79 What aspects of an odontogenic tumor are most important to management decision-making?

Answer 79

Although histology is useful in distinguishing these lesions from one another, it is less important in terms of management. Intervention should be dictated by the behavior of the lesion itself, with particular attention given to the extent of local invasion, disruption of nearby anatomical structures, and destructiveness of the lesion.

Question 80

80 What are common risk factors for malignancies originating from odontogenic cysts and tumors?

Answer 80

Many odontogenic carcinomas are found in sites of prior cysts, (more commonly than odontogenic tumors), and many are noted in edentulous sites on the mandible/ maxilla. Dentigerous cysts are the source of transformation in as many as 25% of cases.

Question 81

81 Describe the clinical presentation of ameloblastoma. (▶ Fig. 13.8)

Answer 81

Peak in the third and fourth decades of life.

Slow-growing, painless bony mass, usually in the posterior mandible.

The tumor is locally invasive, and malignant transformation is rarely noted. The tumor may recur with inadequate resection, especially the solid variant.

Radiology is notable for expansive radiolucent lesions that can be unilocular or multilocular and have a characteristic “soap bubble” or “honeycombed” appearance.

Question 82

82 What is the most common odontogenic tumor?

Answer 82

Ameloblastoma

Question 83

83 Compare and contrast ameloblastoma with calcifying epithelial odontogenic tumors (CEOT; Pindborg tumors).

Answer 83

Both are highly infiltrative and destructive epithelial-derived tumors, presenting as a radiolucent, slow-growing, and painless mass. CEOTs are much less common than ameloblastoma and histopathologically show evidence of scattered calcification with concentric rings known as Liesegang rings. Unlike ameloblastoma, CEOT has large areas of eosinophilic tissue that stain positive for amyloid with Congo red.

Question 84

84 What is the difference between malignant ameloblastoma and ameloblastic carcinoma?

Answer 84

Malignant ameloblastoma is characterized by benign appearing histology but distant metastasis. Ameloblastic carcinoma has the basic ameloblastoma pattern but is dedifferentiated with atypia, hypercellularity, and mitoses, with or without regional or distant metastasis.

Question 85

85 How can malignant ameloblastoma be distinguished from ameloblastoma or ameloblastic carcinoma?

Answer 85

Malignant ameloblastoma is identified by the presence of metastasis, most often to the lungs. Local invasion is frequently aggressive, similar to ameloblastoma. Histology is notable for similar appearance to the primary ameloblastoma, but the hallmarks of malignancy (invasion of surrounding structures, frequent mitotic figures) are seen in ameloblastic carcinoma. Resection of the tumor is recommended in all cases, and although controversial, adjuvant treatment with radiation or chemotherapy is sometimes warranted.

Question 86

86 Why is the adenomatoid odontogenic tumor known as the “two-thirds tumor”?

Answer 86

Adenomatoid odontogenic tumors occur

• in the second and third decades of life
• two-thirds of the time in females
• two thirds are associated with an unerupted/impacted tooth (usually a cuspid),
• two-thirds of which are a canine
• two thirds of the time in the maxilla.

Question 87

87 What are mesenchymal odontogenic neoplasms (no epithelial component)?

Answer 87

1. Odontogenic myxoma
2. Cementoblastoma
3. Central and peripheral odontogenic fibromas

Question 88

88 Compare and contrast odontogenic myxoma with ameloblastoma.

Answer 88

Both tumors are similar in terms of clinical and radiographic presentation in that both are slow growing and usually asymptomatic, both can be quite destructive (displacement/ absorption of tooth roots), both manifest preferentially in the posterior mandible, and both do not impact sensation.

However, myxomas frequently appear earlier (in the third decade vs. the fourth for ameloblastoma), and ameloblastomas originate from the epithelium, whereas myxomas are mesenchymal. Both demand excision with a wide margin of tissue.

Question 89

89 What distinguishes a cementoma from other benign odontogenic tumors?

Answer 89

Cementoma is an outdated term used to indicate a tumor producing cementum (a calcified substance covering the tooth root). There are three different entities previously associated with the term cementoma:

1. Periapical cementoosseous dysplasia
2. Cementoblastoma
3. Ossifying fibroma.

Question 90

90 What clinical features define ameloblastic fibroma?

Answer 90

Ameloblastic fibromas are found primarily in younger patients (seldom over age 40 years), usually in the posterior mandible. They present as a painless, radiolucent mass that often overlies an unerupted tooth.

Question 91

91 What is the natural history of most osteomas of the jaws?

Answer 91

Osteomas are benign hamartomatous bony proliferations, and are made up of compact bone found either on the surface of the jaws in the case of periosteal osteoma or within the bone in endosteal osteomas. An association between multiple osteomas and familial adenomatous polyposis is described in Gardner syndrome.

Question 92

92 What is the cause of mandibular tori?

Answer 92

It is probably multifactorial, with a possible autosomal dominant inheritance. They may also be a result of bone stress.

Question 93

93 What is the recommended treatment for torus palatinus?

Answer 93

Observation, unless there is need for a denture, recurrent traumatic ulceration, or a change in speech

Question 94

94 Describe the presentation and management of central giant cell lesions.

Answer 94

Central giant cell tumors are benign, but locally aggressive lesions affecting the long bones can also occur in the jaws, particularly the anterior mandible. The first through the third decades are most common, and they manifest as an asymptomatic, painless swelling, although pain or numbness is occasionally noted. Curettage is typically an effective treatment, although recurrence should prompt wider resection. Medical interventions have also been described as having some success, notably steroids, interferon, and calcitonin. Bisphosphonate therapy has also been advocated.

Question 95

95 Why is the name aneurysmal bone cyst a misnomer?

Answer 95

Aneurysmal bone cysts are not cysts at all because they lack any endothelial or epithelial lining. Rather, they are expansile osteolytic bone lesions that fill with blood. They are thought to be a variant of giant cell tumor or develop within these tumors.

Question 96

96 Describe the natural history of ossifying fibroma.

Answer 96

Ossifying fibromas are benign growths that stem from mesenchymal cells. They occur most often in the tooth-bearing jaws and are more common in women. They can become quite large but respond to enucleation and curettage if detected early (under 2 to 3 cm). Larger masses require resection, although a large margin is unnecessary as they are unlikely to recur. They progress from radiolucent to mixed to radio-opaque.

Question 97

97 What is the cause of fibrous dysplasia?

Answer 97

Fibrous dysplasia is a genetic condition in which medullary bone is replaced by immature bone and fibrous tissue. It most commonly affects one bone (monostotic—90%) but can be seen in multiple bones (polyostotic), most notably in McCune-Albright syndrome.

Question 98

98 Describe the findings in McCune-Albright syndrome. (▶ Fig. 13.9)

Answer 98

At least two of the following:

1. Hyperfunction of endocrine glands (often manifest with precocious puberty)
2. Cafe-au-lait spots (unilateral)
3. Polyostotic fibrous dysplasia (which can manifest in the mandible/maxilla, among many other locations).

Question 99

99 What pathologic change gives rise to the characteristic mandibular swelling in cherubism?

Answer 99

In cherubism, bone in the mandible (and occasionally maxilla) is gradually replaced by multilocular cysts comprising vascular fibrous tissue with multinucleated giant cells. It is symmetric and usually self-limited and will frequently regress with the onset of puberty, often with total involution. Surgery is rarely warranted to treat ophthalmologic or orthodontic complications. Inheritance is autosomal dominant, with near complete penetrance in males.

Question 100

100 Describe the pathophysiology of osteitis deformans (Paget disease), and how is diagnosis made?

Answer 100

Paget disease arises from increased bone formation and resorption. Dense, sclerotic pagetoid bone will be disorganized and weak and may bend or fracture in earlier stages.

Diagnosis is often delayed by the fact that patients are asymptomatic. Eventually, deep bone pain or characteristic enlargement of the skull, bowing of the legs, hearing loss, or fractures may bring the disease to the attention of the patient or clinician. Diagnosis is confirmed by radiographs, which demonstrate polyostotic or mosaicpatterned bone. Elevated serum alkaline phosphatase and urine hydroxyproline from increased bone turnover are also useful.