COA COA Orthodontic Materials & Equipment 2 — Questions and Answers
Question 1: Which bracket design features a built-in clip that holds the archwire without separate ligatures?
- Traditional twin bracket
- Self-ligating bracket (Correct answer)
- Ceramic bracket
- Lingual bracket
Correct answer: Self-ligating bracket
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?
- Gold alloy
- Stainless steel or nickel-titanium (Correct answer)
- Aluminum
- Titanium dioxide
Correct answer: Stainless steel or nickel-titanium
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?
- To expand the palate transversely
- To prevent upper molars from drifting mesially (Correct answer)
- To correct a posterior crossbite
- To retract upper front teeth
Correct answer: To prevent upper molars from drifting mesially
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?
- Hawley retainer
- Fixed lingual retainer
- Essix retainer (Correct answer)
- Frankel appliance
Correct answer: Essix retainer
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?
- Hemostat
- Ligature director/tucker (Correct answer)
- Band seater
- Scaler
Correct answer: Ligature director/tucker
A ligature director (tucker) has a small hook tip designed to seat and remove elastic o-ties around bracket wings efficiently.
Question 6: Which instrument is used to trim the excess distal end of an archwire after engagement?
- Band scissors
- Distal end cutter (Correct answer)
- Wire-bending pliers
- Torquing pliers
Correct answer: Distal end cutter
A distal end cutter is designed to cut flush the excess archwire extending past the terminal bracket, preventing soft tissue irritation.
COA COA Orthodontic Materials & Equipment 2
Which bracket design features a built-in clip that holds the archwire without separate ligatures?