Resorbability of the roots of primary dentition is explained by:

 # Resorbability of the roots of primary dentition is explained by:

A. Genetically determined

B. Pressure applied by successors

C. Both A and B

D. None

The correct answer is C. Both A and B.

Resorbability of the roots depends on both the above factors.

If there is no successor of primary tooth then it function as a permanent tooth and its root does nor resorb which indicates that its dependency on pressure applied by successor. It also depends on the genetic factors.

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Occlusal fossa of the primary crown is:

 # Occlusal fossa of the primary crown is:

A. Shallower than the permanent

B. Deeper than the permanent

C. Same as permanent

D. Any of the A or B

The correct answer is A. Shallower than the permanent.

Since the thickness of the covering of pulp (enamel and dentin) is less in primary crown, the fossa is shallower as compared to permanent crown.

Pulp chamber is larger in relation to crown size in primary teeth as compared to permanent teeth.

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By what maximum age should the first teeth erupt?

 # Normally, by what maximum age should the first teeth erupt?

A. 10 to 11 months

B. 6 to 8 months

C. 14 to 16 months

D. None of the above

The correct answer is A. 10 to 11 months.

In primary dentition, the variation of eruption has a range of 4-5 months. Since the first tooth erupts at an age of six months, a variation of 4-5 months can be considered normal. 

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Which primary tooth has the longest duration of function?

 # Which primary tooth has the longest duration of function?

A. Mandibular canine

B. Maxillary canine

C. Mandibular second molar

D. Maxillary second molar

The correct answer is B. Maxillary canine.

Deciduous maxillary canine has the longest duration of function and is the last tooth to shed off owing to its long root.

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Average duration of function of primary dentition is:

 # Average duration of function of primary dentition is:

A. 6 years

B. 8 years

C. 10 years

D. 12 years

The correct answer is A. 6 years.

The primary or deciduous dentition is considered to be completed by about 30 months or when the second primary molars are in occlusion. The dentition period includes the time when no apparent changes occur intraorally, i.e. from about 30 months to about 6 years of age.

The primary dentition may be in use from age 2 to 7 or older or about five or more years in all. Some of the teeth are in use from six months until 12 years of age, or a total of eleven and half years. 

Hence, average duration of function of primary dentition is 6 years while the maximum duration is 10 years.

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Intended target cells of H2 histamine receptor blockers

 # Which of the following is the intended target of H2 histamine receptor blockers?

A. Juxtaglomerular cells

B. Basophils

C. Arterial endothelial cells

D. Parietal cells

E. Mast cells

The correct answer is D. Parietal cells.

Histamine stimulates the H2 receptor of the parietal cells of the stomach and is released by basophils and mast cells. 

H2 receptor stimulation induces a proton release into the stomach lumen, decreasing the pH.

H2 receptor blockers reduce the amount of acid in the stomach.

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FALSE regarding biotransformation of drugs is:

 # FALSE regarding biotransformation of drugs is:

A. It usually converts a drug into its lipid soluble non ionized form

B. It generally involves modifications of the chemical structure of the drug

C. It principally occurs in the microsomal enzyme system of the liver

D. The rate may vary significantly between species

The correct answer is A.  It usually converts a drug into its lipid soluble non ionized form.

Biotransformation involves the conversion of a lipid soluble non ionized form of a drug into its more water soluble metabolites.

Biotransformation increases the absorption of the drug into the bloodstream, enhancing the bioavailability of the drug. Water soluble drugs are also easily excreted in the urine.

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