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.