ADAT - Advanced Dental Admission Test Dental Materials & Biomechanics 1

Question 1

Which type of dental ceramic exhibits the highest flexural strength due to its tetragonal zirconia polycrystal (TZP) microstructure?

Accepted Answer

Yttria-stabilized zirconia (Y-TZP)

Answer

Feldspathic porcelain

Answer

Leucite-reinforced glass ceramic

Answer

Lithium disilicate glass ceramic

Question 2

The modulus of elasticity (Young's modulus) of dentin is approximately:

Accepted Answer

18 GPa

Answer

2 GPa

Answer

70 GPa

Answer

200 GPa

Question 3

Which bonding mechanism is primarily responsible for the adhesion of glass ionomer cement to tooth structure?

Accepted Answer

Ionic exchange between carboxylate groups and calcium in hydroxyapatite

Answer

Micromechanical interlocking with etched enamel prisms

Answer

Covalent bonding between MDP monomer and zirconia oxide

Answer

Hydrophobic resin infiltration of the hybrid layer

Question 4

A cantilever fixed partial denture (FPD) places the pontic abutment junction under which primary stress?

Accepted Answer

Tensile stress on the superior aspect of the connector

Answer

Compressive stress on the occlusal surface of the abutment

Answer

Shear stress uniformly distributed along the span

Answer

Torsional stress only at the gingival embrasure

Question 5

Which setting reaction best describes the hardening of zinc phosphate cement?

Accepted Answer

Acid–base reaction forming zinc phosphate salt crystals within an unreacted zinc oxide core

Answer

Free-radical polymerization of methacrylate monomers

Answer

Chelation of zinc ions by polyacrylic acid chains

Answer

Hydration of calcium silicate phases producing calcium silicate hydrate gel

Question 6

Creep in dental amalgam restorations is clinically significant because it leads to:

Accepted Answer

Ditching and marginal breakdown as the alloy flows under sustained occlusal load

Answer

Increased marginal adaptation and reduced microleakage over time

Answer

Spontaneous conversion of gamma-2 phase to gamma-1 phase

Answer

Enhanced corrosion resistance through work hardening at the margins