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 Which of the following statements applies best to the polyvinyl siloxane impression materials (addition silicone)?

a.     Condensation silicones show less dimensional change than polysulfides or polyethers.

b.     Polyethers are stiffer than silicones and polysulfides.

c.     Polyethers show more flow than condensation silicones and polysulfides.

d.     Addition silicones show more permanent deformation than polysulfides and polyethers.

       A comparison of the properties of elastomeric impression materials includes:

a.     Degree of stiffness of elastomeric impression material.

b.     Dimensional stability of elastomeric impression material.

c.     Difficulty to be used for edentulous patients.

d.     One-hour pouring time being most critical.

 

What is the main difference between inelastic and elastic impression materials?

 a.  Ability to reproduce fine details.

b.     Set in a reasonable time.

c.     Can be removed from undercuts.

d.     Can be successfully disinfected.

 

 The dimensional accuracy of impression materials is mostly affected by:

               a. viscosity of the materials

               b. mixing technique of the materials

               c. way of removal of the impression after setting

               d. all of the above                                                                              

 

Which of the following statement is true?

a.The die material wets completely a hydrophobic impression and produce an exact replica.

            b. The hydrophilicity of the impressions leads to the production of accurate casts.

           

 Tear strength of impression materials is dependant on many factors such as:

            a. accuracy of gingival retraction

            b. hemorrhage surrounding the preparation area

            c. flow properties of the impression materials

            d. all of the above

            e. none of the above

 

 Which is the main difference between inelastic and elastic impression materials?

            a. ability to reproduce fine details

            b. set in a reasonable time

            c. can be removed from undercut areas

            d. can be successfully disinfected

 

 When using a polysulfide rubber impression material (Permlastic), greatest accuracy of the cast is produced when:

    a. pouring the impression within an hou

  b. adding more catalyst to the impression material during mixing

 c. allowing the impression material to start the initial setting before placing the tray in the mouth. 

Which of the following is the ideal solution to solve the problem of mesially tilted molar:-
a. Extraction of the third molar
b. Orthodontic up-rightening of tilted molar
c. Performing a three quarter crown preparation on the second molar
d. Performing a telescopic crown on the second molar
e. None of the above

In crown preparation the root should be covered in order to prevent:-
a. Erosion
b. Caries
c. Sensitivity
d. All the above
e. None of the above
 

Which of the following is correct about extrusion of un-apposed dentition:-
a. Extrusion is always seen when there is no apposing dentition
b. Sever extrusion happen in 50% of the cases
c. 1-2 m of extrusion happen in 60% of the cases
d. None of the above

 In order to maintain a healthy periodontium around a fixed partial denture, the amount of
attached gingiva should be at least:-
a. 0.5 mm
b. 1 mm
c. 2 mm
d. 3 mm