The anterior bite plane should separate the posterior teeth by:

 # The anterior bite plane should separate the posterior teeth by:

A. 3-4 mm

B. 4-5 mm

C. 1.5-2 mm

D. 0.5-1 mm

The correct answer is C. 1.5-2 mm.

- Used for correction of deep bite

- It should provide a clearance of 2-3 mm between upper and lower posterior teeth to provide space for

supraeruption

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Distance from the x-ray source to the subjects in midsagittal plane is

# In standard cephalometric arrangement, the distance from the x-ray source to the subjects in midsagittal plane is:

A. 3 feet

B. 4 feet

C. 5 feet

D. 6 feet

The correct answer is C. 5 feet.

- The distance between X-ray film and midsagittal plane of patient's head is - approximately 18 cm or 7 inches.

- The distance between X-ray tube and midsagittal plane of patients head is 5 feet, 60 inches/ 152.4 cm. (KERALA-15) 

- While taking radiographs the operator should stand at a distance of : 6 feet

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Open ended lined cones reduce:

 # Open ended lined cones reduce:

A. Intensity of scattered radiation

B. Intensity of primary radiation

C. Level of scattered radiation

D. All of the above

The correct answer is C. Level of scattered radiation.

The position-indicating device (PID), or cone, appears as an extension of the x-ray tubehead and is used to direct the x-ray beam. Three basic types of PIDs are currently used: (1) conical, (2) rectangular, and (3) round.

The conical PID appears as a closed, pointed plastic cone. When x-rays exit from the pointed cone, they penetrate the plastic and produce scatter radiation. To eliminate cone-produced scatter radiation, the conical PID is no longer used in dentistry. Open-ended, lead-lined rectangular or round PIDs limit the occurrence of scatter radiation.

Both rectangular and round PIDs are typically available in two lengths: short (8-inch) long (16-inch). The long PID is preferred because less divergence of the x-ray beam occurs.

Of the three types of PID, the rectangular type is most effective in reducing patient exposure.

Reference: Dental Radiography Principles and Technique, Fourth Edition, Iannucci and Howerton Page NO 48

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Inherited as an autosomal dominant trait

 # Which one is inherited as an autosomal dominant trait?

A. Lichen planus

B. Bullous Pemphigoid

C. Pemphigus vulgaris

D. White sponge nevus

The correct answer is D. White sponge nevus.

Familial white folded dysplasia is a relatively uncommon condition of the oral mucosa described by Cannon in 1935. The disease appears to follow a hereditary pattern as an autosomal dominant trait but with irregular penetrance and no definite sex predilection.

Reference: Shafer's textbook of oral pathology