Penetration of sealers into the detinal tubules mainly depends on:

 # Penetration of sealers into the dentinal tubules mainly depends on:

A. Sealer thickness

B. Method of obturation

C. Type of final irrigant used

D. Type of sealer

The correct answer is B. Method of obturation.

The smear layer may interfere with the adhesion and penetration of root canal sealers. It also may prevent gutta-percha penetration during thermoplastic techniques. Significant tubular penetrations of gutta-percha and sealers have been reported with thermoplasticized obturations and with dentin-bonded composite resins. Removal of the smear layer also enhances the adhesion of sealers to dentin and tubular penetration. Root canal filling materials adapt better to the canal walls after smear layer removal.

Which of the following statements applies to globular dentin?

 # Which of the following statements applies to globular dentin? 

a. Deposited first along the dentinoenamel junction. 

b. Mineralized by matrix vesicles. 

c. Separates mantle dentin from circumpulpal dentin. 

d. Secreted by immature odontoblasts. 

The correct answer is C. Separates mantle dentin from circumpulpal dentin.

Sometimes mineralization of dentin begins in small globular areas that fail to coalesce into a homogeneous mass. This results in zones of hypomineralization between the globules. These zones are known as globular dentin or interglobular spaces. This dentin forms in the crowns of teeth in the circumpulpal dentin just below the mantle dentin, and it follows the incremental pattern. The dentinal tubules pass uninterruptedly through interglobular dentin, thus demonstrating defect of mineralization and not of matrix formation. 

Which is NOT a paired bone of the skull?

 # Which is NOT a paired bone of the skull?

a. Nasal.

b. Maxilla.

c. Lacrimal.

d. Sphenoid.

The correct answer is D. Sphenoid. 

Out of the 8 cranial bones, Parietal and Temporal are only paired. Occipital, Sphenoid, Frontal and Ethmoid are unpaired bones of the skull. Nasal, Maxilla and Lacrimal bones are paired though they don't constitute the cranium, they are facial bones.

Admixed high copper alloy powder contains:

  # Admixed high copper alloy powder contains:

A. 9-20% copper

B. 13-20% copper

C. 9-30% copper

D. 13-30% copper

The correct answer is A. 9-20% copper.

In low copper alloys, copper is less than 6% by weight. In high copper single composition alloys, 13-30% copper by weight is present whereas in high copper admixed alloys, 9-20% copper is present.