DENTAL MATERIALS (NBDHE)
EXAM WITH CORRECT QUESTIONS
AND ANSWERS 2025
1. Adhesion - CORRECT-ANSWERSthe chemical attraction between *unlike* molecules
2. Cohesion - CORRECT-ANSWERSthe chemical attraction between *like* molecules
3. Coefficient of thermal expansion - CORRECT-ANSWERSAn index which indicates how
one material reacts to temperature extremes in relation to another
4. Compressive strength - CORRECT-ANSWERSthe force at which a material breaks under
pressure
5. Creep - CORRECT-ANSWERSslow dimensional change caused by compression
6. Ductility - CORRECT-ANSWERSthe ability to undergo change of form without breaking
7. Elasticity - CORRECT-ANSWERSa material's ability to recover its initial shape after
undergoing a force
8. Galvanism - CORRECT-ANSWERSAn electrical current generated by dissimilar metals in
an acidic environment
9. Gelation - CORRECT-ANSWERSThe process of gelling (solidification by cold)
10. Imbibition - CORRECT-ANSWERSAbsorption of a solvent by a gel
,11. Malleability - CORRECT-ANSWERSA material's capacity to be shaped by force or pressure
12. Microleakage (percolation) - CORRECT-ANSWERSpassage of oral fluids/bacteria into and
out of tooth structure due to a marginal gap or failure of the marginal (restorative) seal
13. Polymerization - CORRECT-ANSWERSthe linking, branching, or cross-linking of smaller
molecules to generate a larger molecule, as seen with composite bonding and
impression setting
14. Proportional limit - CORRECT-ANSWERSthe force at which a material cannot return to its
original shape
15. Syneresis - CORRECT-ANSWERSContraction of a gel due to the loss of a solvent
16. Tensile strength - CORRECT-ANSWERSThe force needed to stretch a material to the
point of fracture
17. Viscosity - CORRECT-ANSWERSresistance to flow (the higher it is, the lower the flow)
18. *mouthwash has lower than toothpaste
19. amalgam - CORRECT-ANSWERSan alloy of mercury with silver, copper, tin, and zinc
20. silver - CORRECT-ANSWERSa base metal that is susceptible to corrosion
21. Why is copper added to an amalgam? - CORRECT-ANSWERSto minimize corrosion
(gamma II phase eliminated)
, 22. Desirable features of amalgams: - CORRECT-ANSWERS(a) durable
23. (b) compressive strength is similar to enamel
24. (c) relatively inexpensive
25. undesirable features of amalgams: - CORRECT-ANSWERS(a) unattractive
26. (b) high thermal conductivity
27. (c) dimensionally unstable (creep)
28. (d) delayed expansion if contaminated
29. (e) requires tooth support
30. (f) fracturable by excessive occlusion
31. (g) susceptible to galvanism when new
32. Polishing amalgams: - CORRECT-ANSWERS-*Can reduce the rate of corrosion (because
of less surface area)*
33. -Move from coarse to fine agents when polishing to remove surface tarnish, stains,
flash, roughness
34. -Final polish in the mouth is *tin oxide*
35. -Use a light tough with water and short bursts when power polishing with a rubber cup
to avoid odontoblast-damaging heat
EXAM WITH CORRECT QUESTIONS
AND ANSWERS 2025
1. Adhesion - CORRECT-ANSWERSthe chemical attraction between *unlike* molecules
2. Cohesion - CORRECT-ANSWERSthe chemical attraction between *like* molecules
3. Coefficient of thermal expansion - CORRECT-ANSWERSAn index which indicates how
one material reacts to temperature extremes in relation to another
4. Compressive strength - CORRECT-ANSWERSthe force at which a material breaks under
pressure
5. Creep - CORRECT-ANSWERSslow dimensional change caused by compression
6. Ductility - CORRECT-ANSWERSthe ability to undergo change of form without breaking
7. Elasticity - CORRECT-ANSWERSa material's ability to recover its initial shape after
undergoing a force
8. Galvanism - CORRECT-ANSWERSAn electrical current generated by dissimilar metals in
an acidic environment
9. Gelation - CORRECT-ANSWERSThe process of gelling (solidification by cold)
10. Imbibition - CORRECT-ANSWERSAbsorption of a solvent by a gel
,11. Malleability - CORRECT-ANSWERSA material's capacity to be shaped by force or pressure
12. Microleakage (percolation) - CORRECT-ANSWERSpassage of oral fluids/bacteria into and
out of tooth structure due to a marginal gap or failure of the marginal (restorative) seal
13. Polymerization - CORRECT-ANSWERSthe linking, branching, or cross-linking of smaller
molecules to generate a larger molecule, as seen with composite bonding and
impression setting
14. Proportional limit - CORRECT-ANSWERSthe force at which a material cannot return to its
original shape
15. Syneresis - CORRECT-ANSWERSContraction of a gel due to the loss of a solvent
16. Tensile strength - CORRECT-ANSWERSThe force needed to stretch a material to the
point of fracture
17. Viscosity - CORRECT-ANSWERSresistance to flow (the higher it is, the lower the flow)
18. *mouthwash has lower than toothpaste
19. amalgam - CORRECT-ANSWERSan alloy of mercury with silver, copper, tin, and zinc
20. silver - CORRECT-ANSWERSa base metal that is susceptible to corrosion
21. Why is copper added to an amalgam? - CORRECT-ANSWERSto minimize corrosion
(gamma II phase eliminated)
, 22. Desirable features of amalgams: - CORRECT-ANSWERS(a) durable
23. (b) compressive strength is similar to enamel
24. (c) relatively inexpensive
25. undesirable features of amalgams: - CORRECT-ANSWERS(a) unattractive
26. (b) high thermal conductivity
27. (c) dimensionally unstable (creep)
28. (d) delayed expansion if contaminated
29. (e) requires tooth support
30. (f) fracturable by excessive occlusion
31. (g) susceptible to galvanism when new
32. Polishing amalgams: - CORRECT-ANSWERS-*Can reduce the rate of corrosion (because
of less surface area)*
33. -Move from coarse to fine agents when polishing to remove surface tarnish, stains,
flash, roughness
34. -Final polish in the mouth is *tin oxide*
35. -Use a light tough with water and short bursts when power polishing with a rubber cup
to avoid odontoblast-damaging heat
