Tissue displacement, facial pattern and complete dentures

Correct answer: D. To displace the tissue both laterally and vertically so the finish line is exposed and reproduced

• A. Cement selection follows from the restorative material, not from the retraction technique.
• B. Retraction does not harden tissue. Chemical agents cause transient shrinkage through vasoconstriction or protein precipitation, not hardening.
• C. Retraction is a temporary, reversible displacement. Permanently repositioning the margin apically is crown lengthening, a surgical procedure.
• D. Correct. Retraction has two components: lateral displacement widens the sulcus so impression material can flow around the margin, and vertical displacement exposes a band of unprepared tooth apical to the finish line.

Correct answer: C. High (steep)

• A. A cephalogram quantifies the angle, but the facial pattern is readily assessed clinically from a profile photograph.
• B. An average angle would be the mesofacial pattern, which was not what the photograph showed.
• C. Correct. A steep mandibular plane accompanies a vertical growth pattern — a long lower face, a backward-rotating mandible, and a tendency to anterior open bite. This is the classic Class II hyperdivergent face.
• D. A low or flat mandibular plane belongs to the horizontal, brachyfacial pattern with a strong deep bite and a square lower face.

Correct answer: D. A conventional rigid heat-cured acrylic complete denture

• A. Flexible nylon bases distort under load, cannot be reliably relined, and give poor stability in a fully edentulous arch.
• B. Porcelain refers to the artificial teeth, not the denture base. Porcelain teeth are heavy, abrade the opposing ridge, and are now rarely chosen.
• C. Cast metal frameworks are for partial dentures, where clasps engage remaining teeth. There is nothing to clasp here.
• D. Correct. A rigid heat-cured acrylic base adapts accurately to the tissue, transmits load evenly, and — importantly — can be relined or rebased when the ridge resorbs. It remains the standard for complete dentures.

Note: If retention is the presenting complaint, the underlying cause matters — a poor peripheral seal, a resorbed ridge, or an overextended flange each call for different corrections. Implant retention is the definitive answer for a severely resorbed mandible.