Restricting size of beam is done by:

 # Restricting size of beam is done by:

A. Collimator

B. Transformer

C. Tube head seal

D. Beam indicating device

The correct answer is A. Collimator.

A collimator is a metallic barrier with an aperture in the middle used to restrict the size of the x-ray beam and the volume of tissue irradiated. Round and rectangular collimators are most frequently used in dentistry. Dental x-ray beams are usually collimated to a circle 4 inches (7 cm) in diameter at the patient’s face. A round collimator is a thick plate of radiopaque material (usually lead) with a circular opening centered over the port in the x-ray head through which the x-ray beam emerges. Typically, round collimators are built into open-ended aiming cylinders. Rectangular collimators further limit the size of the beam to just larger than the x-ray film, further reducing patient exposure. Some types of film-holding instruments also provide rectangular collimation of the x-ray beam. 

Reference: White and Pharoah's Oral Radiology, 7th Edition

In CBCT technology, the speed with which individual images are acquired is called:

 # In CBCT technology, the speed with which individual images are acquired is called:

A. Running rate

B. Frame rate

C. Projection rate

D. Image rate

The correct answer is B. Frame rate.

The number of images constituting the projection data throughout the scan is determined by the detector frame rate (number of images acquired per second), the completeness of the trajectory arc (180 to 360 degrees), and the rotation speed of the source and detector. The number of basis images making up a single scan set may be fixed or variable. Higher frame rates have both desirable and undesirable effects. Higher frame rates increase the signal-to-noise ratio, producing images with less noise and reducing metallic artifacts. However, a higher frame rate is associated with a longer scan time and higher patient dose. In addition, more data are obtained, and primary reconstruction time is increased.

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Hemorrhage secondary to heparin administration can be corrected by administration of:

 # Hemorrhage secondary to heparin administration can be corrected by administration of:

A. Vitamin K

B. Whole blood

C. Protamine

D. Ascorbic acid

The correct answer is C. Protamine.

The half life of intravenous heparin is about one hour and if a patient bleeds, it is usually sufficient just to discontinue the infusion; however if the bleeding is severe, the excess can be neutralized with intravenous protamine.

# Most reliable method of identification of a person is by:

# Most reliable method of identification of a person is by:

A. Anthropometry

B. DNA finger printing

C. Dactylography

D. Dentition

The correct answer is C. Dactylography.

• Derived from GK word daktylose-finger ,graphein- to write

Dactylography is the method of identification based on unique epidermal ridge pattern on the tips of fingers. It is a most accurate and unfailing method of positive identification. No Two Individual will have identical fingerprints It is better method of identification than DNA profiling. DNA profiling would be same in identical twins but fingerprints are different. Fingerprints remain permanent throughout life and even after death and in advance stage of decomposition. Fingerprints have general characteristic ridge patterns that permit them to be systematically classified. Pattern can be easily emailed and printed, enabling intercontinental criminals to be caught easily.

Marked salivary gland hypofunction

 # Stimulated whole salivary flow rate of less than _____ ml/min indicates marked salivary gland hypofunction. 

A. 0.6 

B. 0.7 

C. 0.8 

D. 0.9 

The correct answer is B. 0.7.

It is difficult to define absolute “normal” values for salivary output due to great interindividual variability and, consequently, a large range of normal values exists. About 0.3– 0.4 mL/min for unstimulated flow and 1.5–2.0 mL/min for stimulated flow are considered normal. Unstimulated whole

saliva flow rates of < 0.1 mL/min and stimulated whole saliva flow rates of < 0.7 mL/min are abnormally low and indicative of marked salivary gland hypofunction. Higher levels of output do not guarantee that function is normal, however, as they may represent marked hypofunction for some individuals. Therefore, these stated values represent a lower limit of normal and should serve only as a guide for the clinician.

Reference: Burket’s Oral Medicine, Thirteenth Edition

The presence of fluoride in communal water supplies have demonstrated appreciably lesser benefits, this is due to:

 # The presence of fluoride in communal water supplies have demonstrated appreciably lesser benefits, this is due to 

A. Adverse effect 

B. Halo effect 

C. Bacteriostatic effect 

D. None of the above 

The correct answer is B. Halo effect.

Several studies concerning the reduced prevalence of dental caries associated with the presence of fluoride in communal water supplies have demonstrated appreciably lesser benefits, typically ranging between 18% and 30%. This decrease in attributable benefit is due to the so-called halo effect associated with the preparation of numerous foods and beverages in fluoridated communities and their consumption in nonfluoridated communities.

Reference: Mc Donald 2nd South Asian Edition

The reversal agent used in clinical practice to treat benzodiazepine overdose:

 The reversal agent used in clinical practice to treat benzodiazepine overdose

A. Romazicon 

B. Naloxone

C. Sublimaze

D. Demerol

The correct answer is A. Romazicon.

-Flumazenil (Romazicon) is a direct, specific reversal agent used in clinical practice to treat benzodiazepine overdose. Pharmacologically, it acts as a competitive antagonist at the benzodiazepine receptor sites in the CNS. 

-Naloxone is a life-saving medication that can reverse an overdose from opioids, including heroin, fentanyl, and prescription opioid medications.

-Fentanyl (Sublimaze) is a potent synthetic opiate agonist. A dose of 0.1 mg is approximately equivalent to 10 mg of morphine or 75 mg of meperidine. Fentanyl acts rapidly, and after intramuscular injection the onset occurs in 7–15 min; duration of effects is 1– 2 h.

-Meperidine (Demerol) is a synthetic opiate agonist, closely related to fentanyl in chemical structure.

Reference: Mc Donald 2nd South Asian Edition