RDA Practice Exam – California RDA Test Prep & Free Practice Test (2025)

A model trimmer is used to trim or grind down dental models, usually made of plaster or stone, for a more accurate fit in the patient's mouth. This equipment is not used to determine centric relation.

A dental lathe is used to shape and polish dental restorations such as crowns, bridges, and dentures. It is not used for determining centric relation.

A vacuum former is used to fabricate custom dental appliances, such as mouthguards or retainers. It is not used for determining centric relation.

The correct answer is B Articulator. This is a mechanical device that simulates the patient's jaw movements and allows the dentist to find the centric relation, which is the correct relationship between the upper and lower jaws.