Restorative Dentistry and Dental Materials Flashcards

Which property of dental composite resins is most responsible for post-operative sensitivity?

Answer: Polymerization shrinkage creating gap formation

Polymerization shrinkage (1–5% volumetric) creates contraction stress at the bonded margins, leading to gap formation and post-operative sensitivity.

Amalgam's strength is primarily derived from which phase?

Answer: Gamma-1 phase (silver-mercury)

The gamma-1 phase (Ag2Hg3) is the matrix phase that gives amalgam its strength, while gamma-2 (Sn7-8Hg) is the weakest and most corrosion-prone phase.

Dental porcelain is classified as a ceramic primarily because it contains:

Answer: Inorganic non-metallic crystalline or glass materials

Ceramics are inorganic, non-metallic materials; dental porcelain is primarily composed of silica, feldspar, and alumina in a glass matrix.

The retention of a full-crown preparation is most influenced by:

Answer: Taper of the axial walls (convergence angle)

Axial wall taper (convergence angle) is the most critical retention factor; ideally 6–10° total occlusal convergence maximizes both retention and withdrawal path.

Glass ionomer cement bonds to tooth structure primarily through:

Answer: Ionic bonding to calcium in hydroxyapatite

Glass ionomer cement bonds chemically to tooth structure via ionic interactions between its polyacrylic acid component and calcium and phosphate in hydroxyapatite.

Which composite placement technique best minimizes polymerization shrinkage stress?

Answer: Oblique incremental placement

Oblique (diagonal) incremental placement reduces the C-factor (ratio of bonded to unbonded surfaces) and allows shrinkage stress relief as each increment cures.