COA COA Orthodontic Materials & Equipment 2

Question 1

Which bracket design features a built-in clip that holds the archwire without separate ligatures?

Accepted Answer

Self-ligating bracket

Answer

Self-ligating brackets have an integrated gate or clip mechanism that secures the archwire, reducing friction and appointment time.

Question 2

From what materials are modern orthodontic archwires most commonly fabricated?

Accepted Answer

Stainless steel or nickel-titanium

Answer

Modern archwires are predominantly made from stainless steel for rigidity or nickel-titanium for flexibility and memory.

Question 3

What is the primary function of a Nance appliance?

Accepted Answer

To prevent upper molars from drifting mesially

Answer

A Nance appliance is a fixed space maintainer that uses an acrylic button on the palate to prevent upper molars from moving forward.

Question 4

Which retainer type is fabricated from clear thermoplastic material that fits over the teeth?

Accepted Answer

Essix retainer

Answer

An Essix retainer is vacuum-formed from clear thermoplastic, providing an esthetic and removable retention option.

Question 5

Which instrument is specifically designed to place and remove elastomeric o-tie ligatures on brackets?

Accepted Answer

Ligature director/tucker

Answer

A ligature director (tucker) has a small hook tip designed to seat and remove elastic o-ties around bracket wings efficiently.

COA - Certified Orthodontic Assistant Practice Test