Prosthodontics Flashcards

A patient presents with a worn complete denture showing reduced OVD. What is the consequence of significantly increasing the OVD during denture replacement?

Answer: Muscle fatigue, discomfort, and difficulty with the freeway space

Significantly increasing the OVD beyond the physiological range eliminates the freeway space, causing the muscles of mastication to be constantly stretched. This leads to muscle fatigue, jaw ache, clicking sounds, and difficulty wearing the denture. Any increase should be made gradually and kept within the patient's adaptive capacity.

Which impression technique is most appropriate for recording a flabby anterior ridge for a complete upper denture?

Answer: Altered cast technique (selective pressure/mucostatic impression of flabby tissue with functional impression of the firm ridge)

The altered cast technique (modified impression technique) records the flabby tissue in its undisplaced state using a low-viscosity mucostatic material (such as low-viscosity silicone through a window cut in the special tray), while the firm tissue is recorded under functional pressure. This prevents the denture from displacing the flabby tissue and dislodging during function.

What is the most common cause of denture stomatitis (Newton's classification)?

Answer: Candida albicans colonisation on the fitting surface

Denture stomatitis is primarily caused by Candida albicans colonisation on the fitting surface of the denture, particularly in patients who wear their dentures overnight. The warm, moist, acidic environment under the denture favours fungal growth. Treatment involves antifungal therapy (miconazole or nystatin), improved denture hygiene, and removing dentures at night.

When designing an RPD, what is the function of a reciprocal arm (reciprocating element)?

Answer: To counteract the displacing force of the retentive clasp during insertion and removal

The reciprocal arm is placed on the opposite side of the tooth from the retentive clasp and contacts the tooth above the survey line (suprabulge). Its function is to counteract the lateral force exerted by the retentive clasp tip as it flexes over the height of contour during insertion and removal, preventing tooth movement.

What is the recommended minimum connector width for a chrome cobalt palatal strap in an upper RPD?

Answer: 8mm or greater

A chrome cobalt palatal strap should be at least 8mm wide (though 8–12mm is typical) to provide adequate rigidity while maintaining patient comfort. The strap design is less tissue coverage than a full palatal plate and is well-tolerated when properly designed. If made too narrow, it loses rigidity and feels like a wire pressing against the palate.

A patient with a Kennedy Class III modification 1 partial denture (bounded saddle with additional saddle) complains that the denture feels loose. What is the most likely cause?

Answer: Inadequate retention from clasp arms not engaging the undercut

Poor retention in bounded saddle RPDs is most commonly caused by clasp arms that do not engage sufficient undercut on the abutment teeth. The retentive clasp tip should engage a 0.25mm undercut for chrome cobalt or 0.50mm for wrought wire clasps. Survey and design review is needed, potentially adjusting or remaking clasps to engage the correct undercut depth.