CDT Orthodontic Appliance Construction 2

Question 1

Which wire alloy is preferred for fabricating Adams clasps on removable orthodontic appliances due to its springiness and formability?

Accepted Answer

Stainless steel 0.7mm hard wire

Answer

Hard stainless steel wire (0.7mm) provides the ideal combination of stiffness and springiness needed for Adams clasps to engage undercuts effectively.

Question 2

When constructing a Hawley retainer, the labial bow should contact the anterior teeth at which third of the crown?

Accepted Answer

Middle third

Answer

The labial bow of a Hawley retainer is positioned at the middle third of the anterior crowns to maintain tooth position without impinging on the gingiva.

Question 3

A palatal expander that uses a jackscrew mechanism and is cemented to molar bands is best described as which appliance type?

Accepted Answer

Rapid Palatal Expander (RPE)

Answer

A Rapid Palatal Expander (RPE) uses a midline jackscrew bonded or banded to the molars to apply heavy orthopaedic forces that open the mid-palatal suture.

Question 4

What is the primary purpose of incorporating ball clasps (bullet clasps) into a removable orthodontic appliance?

Accepted Answer

To provide retention by engaging embrasures between teeth

Answer

Ball clasps engage the interproximal embrasure between adjacent teeth, providing passive retention for the appliance without wrapping around individual teeth.

Question 5

During acrylic processing of a removable orthodontic appliance, what defect results from too-rapid polymerization caused by excessive heat?

Accepted Answer

Voids and porosity

Answer

Excessively rapid polymerization generates heat faster than it can dissipate, causing boiling of the monomer and leaving voids and porosity within the acrylic.

(CDT) Certified Dental Technicians Practice Test

(CDT) Certified Dental Technicians Practice Test

CDT Orthodontic Appliance Construction 2