Osteogenesis imperfecta:

 # Osteogenesis imperfecta: 

a. Is a sex linked disorder of bones that develop in cartilage

b. Manifests with blue sclera which are pathognomonic of this disease 

c. May be associated with deafness 

d. Has associations with amelogenesis imperfecta

The correct answer is B. Manifests with blue sclera which are pathognomonic of this disease.

A second characteristic clinical feature of osteogenesis imperfecta is the occurrence of pale blue sclerae. The sclerae are abnormally thin, and for this reason the pigmented choroid shows through and produces the bluish color. However, the appearance of blue sclera is not confined to this disease since it may also be seen in osteopetrosis, fetal rickets, Turner syndrome, Paget’s disease, Marfan syndrome, and Ehlers-

Danlos syndrome, as well as in normal infants. While the blue sclerae are a prominent sign in this disease, they are not invariably present. In a series of 42 patients reported by Bauze and his associates, 12 of the patients had white sclerae, and these were generally found in the older patients with the more severe disease and earlier onset of fractures. 

Radiographic finding in Pindborg tumor:

 # Radiographic finding in Pindborg tumor: 

a. Sun-burst appearance 

b. Onion-peel appearance 

c. Driven-snow appearance 

d. Cherry-blossom appearance 

The correct answer is C. Driven snow appearance.

A calcifying epithelial odontogenic tumor (Pindborg tumor) may show considerable radiographic variation. In some cases, the lesion appears as either a diffuse or a well-circumscribed unilocular radiolucent area, while in other cases there may appear to be a combined pattern of radiolucency and radiopacity with many small, irregular bony trabeculae traversing the radiolucent area in many directions, producing a multilocular or honeycomb pattern. Scattered flecks of calcification throughout the radiolucency have given rise to the descriptive term of a ‘driven snow’ appearance. In some instances, the lesion is totally radiolucent and is in association with an impacted tooth, thus leading to a mistaken clinical diagnosis of a dentigerous cyst. 

The cyst with the highest recurrence rate is:

  # The cyst with the highest recurrence rate is: 

A. Keratocyst

B. Periapical cyst

C. Nasoalveolar cyst

D. Globulomaxillary cyst

The correct answer is A. Keratocyst.

In 1967, Toller suggested that the OKC may best be regarded as a benign neoplasm rather than a conventional cyst based on its clinical behavior. The WHO has reclassified the lesion as a tumor based on several factors, that formed the basis of this decision.

Behavior: The KOT is locally destructive and has a high recurrence rate.

Histopathology: The basal epithelial layer of KOT shows proliferation and budding into the underlying connective tissue in the form of daughter cysts and mitotic figures are frequently found in the suprabasal layers of the lesional epithelium. 

Dentigerous cyst is suspected if the follicular space is more than:

 # Dentigerous cyst is suspected if the follicular space is more than: 

a. 2-3 mm 

b. 3-4 mm 

C. 1-2 mm 

d. More than 5 mm 

The correct answer is D. More than 5 mm.

One of the most difficult differential diagnoses to make is between a small dentigerous cyst and a hyperplastic follicle. A cyst should be considered with any evidence of tooth displacement or considerable expansion of the involved bone. The size of the normal follicular space is 2 to 3 mm. If the follicular space exceeds 5 mm, a dentigerous cyst is more likely. If uncertainty remains, the region should be reexamined in 4 to 6 months to detect any increase in size or any influence on surrounding structures characteristic of cysts.

Reference: Oral radiology Principles and Interpretation, 7th Edition Stuart C. White, Michael J. Pharoah