Prosthodontics: Fixed and Removable Flashcards

A 65-year-old patient requires a new maxillary complete denture. Upon delivery, the patient immediately complains of a persistent gagging sensation. Clinical examination reveals the denture is stable and retentive. Which of the following is the most probable cause of the patient's complaint?

Answer: The posterior border of the denture is overextended onto the soft palate.

The gag reflex is triggered by stimulation of the soft palate. If the posterior border of a maxillary denture extends beyond the vibrating line (the junction of the hard and soft palate) and onto the movable soft palate, it will elicit a gagging sensation. While other factors can cause issues, overextension in this specific area is the most direct cause of gagging.

A patient requires a three-unit fixed partial denture to replace tooth #30. According to Ante's Law, which of the following principles must be met for abutment selection?

Answer: The combined root surface area of the abutment teeth should be equal to or greater than that of the tooth being replaced.

Ante's Law is a fundamental guideline in fixed prosthodontics which states that for a fixed partial denture to have a favorable long-term prognosis, the combined pericemental area (root surface area) of the abutment teeth should be equal to or greater than the pericemental area of the tooth or teeth being replaced. This ensures the abutments can withstand the additional occlusal load.

When designing a fixed partial denture for a posterior, non-esthetic area, which pontic design is considered the most hygienic due to its lack of contact with the residual ridge?

Answer: Sanitary (or hygienic)

The sanitary or hygienic pontic is designed with a significant space between the pontic and the underlying tissue. This complete clearance allows for easy cleaning and optimal tissue health, making it the most hygienic option, though it is generally not used in esthetic zones.

A patient presents with a Kennedy Class I removable partial denture (RPD) opposing a complete denture. What is the primary function of an indirect retainer in this RPD design?

Answer: To counteract lifting forces on the distal extension bases.

In a distal extension RPD, a fulcrum line exists between the most posterior rests. When sticky foods create lifting forces on the denture base, the denture can rotate around this fulcrum line. The indirect retainer, placed anterior to the fulcrum line, acts as a lever to resist this rotational movement and prevent the denture base from lifting away from the tissues.

A patient with limited interocclusal clearance (less than 1.0 mm) on a mandibular second molar requires a full coverage crown. The patient has a history of bruxism. Which of the following materials is most suitable for this situation?

Answer: Full-contour zirconia

Full-contour zirconia has very high flexural strength, allowing it to be used in thin sections. It requires the least amount of occlusal reduction, with a minimum of 0.5 mm, and an ideal of 1.0-1.5 mm. This makes it the ideal choice for posterior crowns in areas with limited occlusal space and high occlusal forces, such as in a patient with bruxism. Other ceramic materials require significantly more reduction (typically 1.5-2.0 mm) to achieve adequate strength.

For a mandibular Kennedy Class I removable partial denture using the canines as the terminal abutments, which clasp assembly is specifically designed to be 'stress-releasing' by minimizing torquing forces on the abutment teeth during function?

Answer: An RPI system (mesial Rest, Proximal plate, I-bar clasp).

The RPI system is a stress-releasing clasp assembly designed for distal extension cases. The mesial rest moves the fulcrum away from the edentulous space, the distal proximal plate guides the path of insertion and disengages during function, and the I-bar clasp engages a minimal undercut. This combination allows the denture base to move slightly toward the tissue under load without transmitting harmful torque to the abutment tooth.