Prosthodontic & Orthodontic Appliance Fabrication Flashcards

What is the purpose of degassing (oxidizing) a metal coping before applying opaque porcelain in PFM crown fabrication?

Answer: To remove surface oxides and contaminants that would inhibit ceramic bonding

Degassing burns off surface contaminants and forms a controlled oxide layer that chemically bonds with the opaque porcelain for a durable metal-ceramic junction.

Which articulator mounting technique is used to transfer the relationship of the maxillary arch to the temporomandibular joint using a face-bow?

Answer: Facebow transfer mounting

A facebow transfer records the spatial relationship between the maxillary teeth and the TMJ condyles, allowing the articulator to replicate this relationship when mounting the maxillary cast.

During RPD framework fabrication, what is the function of a rest seat on an abutment tooth?

Answer: To support the framework vertically and prevent tissue-ward movement

Rest seats accept the occlusal, incisal, or cingulum rests that vertically support the RPD framework, preventing it from settling into soft tissue.

A technician is pouring an irreversible hydrocolloid (alginate) impression. Which type of gypsum is most appropriate to produce a working cast?

Answer: Type III dental stone

Type III dental stone has sufficient strength for working casts poured from alginate impressions and is compatible with the moisture retained in hydrocolloid materials.

In orthodontic appliance fabrication, what is the clinical indication for a tongue crib (tongue guard) appliance?

Answer: To deter tongue thrusting habits that contribute to anterior open bite

A tongue crib creates a physical barrier that prevents the tongue from resting or thrusting between anterior teeth, helping to eliminate the habit causing an anterior open bite.

When processing a complete denture in compression molding, at which stage is the flask opened to check for short pour (insufficient acrylic) before final curing?

Answer: During the trial pack (dough stage) prior to final closure

The trial pack at the dough stage allows the technician to check acrylic distribution and eliminate excess flash before final flask closure and curing.

Which component of an RPD framework connects major connectors to clasps, rests, and indirect retainers?

Answer: Minor connectors

Minor connectors are the rigid linking elements that join all minor components (clasps, rests, indirect retainers) to the major connector of the RPD framework.