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

Which one of the following conditons is least likely to be associated with an increased risk of oral cancer?

 # Which one of the following conditons is least likely to be associated with an increased risk of oral cancer? 

a. Actinic Cheilosis 

b. Erythroplakia 

c. Leukoedema 

d. Leukoplakia 

The correct answer is C. Leukoedema. 

Leukoedema is a white and veil‐like alteration of the oral mucosa that is merely considered a normal variant. The condition is often encountered bilaterally in the buccal mucosa and sometimes at the borders of the tongue. Leukoedema is less clinically evident after stretching the mucosa, but reappears after this manipulation is discontinued.

Reference: Burket's Oral Medicine

Disadvantages of using a GRID is:

 # Disadvantages of using a GRID is: 

a. Increased patient exposure 

b. Decreased Patient exposure 

c. Increased fogging of the film 

d. Increased secondary radiation 

The correct answer is A. Increased patient exposure. 

Although radiographic grids reduce scattered radiation and improve contrast and resolution, they result

in higher patient exposure. Cephalometry does not require the use of grids. However, grids could improve the radiographic appearance of fine structures, such as trabecular architecture, and aid in the diagnosis of disease.

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

The maximum penetration among the following is seen with which ray:

 # The maximum penetration among the following is seen with which ray: 

a. Alpha 

b. Beta 

c. Gamma 

d. Electron Beam 

The correct answer is C. Gamma.

Gamma (γ) rays originate in the nuclei of radioactive atoms. They typically have greater energy than x rays. In contrast, x rays are produced outside the nucleus and result from the interaction of electrons with large atomic nuclei in x-ray machines. The higher energy types of radiation in the electromagnetic spectrum— ultraviolet rays, x rays, and γ rays—are capable of ionizing matter. Some properties of electromagnetic radiation are best explained by quantum theory, whereas others are most successfully described by wave theory.

PGCEE MDS 2022: The most unwanted side effect seen with Herbst appliance is:

 # The most unwanted side effect seen with Herbst appliance is:

A. Lower incisor proclination

B. Frequent breakage of the appliance

C. Downward rotation of palate

D. Mandible rotate anticlockwise

The correct answer is A. Lower incisor proclination.

The most unwanted side effects seen with Herbst appliance are: 

- More chance of labial tipping as well as proclination of mandibular incisors

- Retrusion of maxillary incisors

Reference: Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation. Am J Orthod. 1979;76(4):423–442.

Salivary gland stone most commonly involves:

 # Salivary gland stone most commonly involves: 

a. sublingual gland 

b. Submandibular gland 

c. Parotid gland 

d. Lingual glands 

The correct answer is B. Submandibular gland. 

Sialoliths (salivary calculi or salivary stones) are calcified organic masses that form within the secretory system of the salivary glands. Although the exact mechanism of sialolith formation has not been established, it has been proposed that microcalculi are frequently formed in salivary ducts during periods of secretory inactivity. 

Sialoliths occur most commonly in the submandibular glands (80–90%), followed by the parotid (5–15%) and sublingual (2–5%) glands, and only very rarely occur in the minor salivary glands. Spontaneous secretion in the minor and sublingual salivary glands may provide continuous salivary flow, thereby preventing stasis.

The higher rate of sialolith formation in the submandibular glands is due to: (1) the torturous course of Wharton’s duct; (2) the higher calcium and phosphate levels of the secretions contained within; (3) the dependent position of the submandibular glands which leaves them prone to stasis; and (4) the increased mucoid nature of the secretion. In addition, since the submandibular and parotid glands’ secretion is dependent on nervous stimulation, in its absence, secretory inactivity increases the risk of stone development.