Prosthodontics: Fixed and Removable Flashcards

Which of the following is the MOST important property of a die stone used for crown fabrication?

Answer: Low setting expansion and high compressive strength

Die stone requires minimal setting expansion (to maintain accuracy) and high compressive strength to withstand waxing and die trimming without fracture.

A patient in centric occlusion shows heavy contact on the mesial incline of an upper molar cusp and the distal incline of a lower molar cusp. This type of premature contact is classified as:

Answer: A DURD (distal upper, mesial lower) contact in centric relation

A premature contact on the distal incline of an upper cusp (DUML) or mesial lower sliding distally from CR to CO is characterized as a DURD/CR discrepancy contact.

All-ceramic crowns are considered contraindicated in which clinical situation?

Answer: Patients with documented bruxism and heavy posterior occlusal forces

Patients with bruxism generate extreme occlusal forces that can fracture all-ceramic restorations, particularly in the posterior region where forces are greatest.

The major connector for a maxillary removable partial denture should:

Answer: Be rigid and positioned at least 6 mm from the gingival margins

A rigid major connector is essential for force distribution, and placement at least 6 mm from gingival margins prevents tissue irritation and gingival inflammation.

The primary advantage of using a custom impression tray over a stock tray for a crown impression is:

Answer: Custom trays provide uniform thickness of impression material around the prepared tooth

Uniform material thickness in a custom tray reduces dimensional distortion and shrinkage variation, resulting in a more accurate impression of the preparation and margins.

During try-in of a wax denture, the patient's upper lip appears flat and unsupported with insufficient tooth display at rest. The appropriate correction is to:

Answer: Move the anterior teeth labially or increase their incisal length

Insufficient labial tooth display and poor lip support are corrected by repositioning the maxillary anterior teeth labially and/or increasing incisal length at the wax try-in stage.

Which material property is most responsible for the clinical failure of zinc phosphate cement as a luting agent in high-moisture or pulpally challenged teeth?

Answer: High initial acidity causing pulp irritation and solubility in oral fluids

Zinc phosphate cement has a low initial pH (~3.5), which can irritate vital pulps, and it is relatively soluble in oral fluids over time, leading to marginal leakage.