Orthodontic Wires & Biomechanics

Q: Which archwire is used for initial alignment due to high flexibility?

NiTi. NiTi has the lowest stiffness and shape memory, ideal for alignment.

Q: The stiffest commonly used archwire is:

Stainless steel. Stainless steel has the highest stiffness for finishing/sliding.

Q: MBT and Roth refer to:

Bracket prescriptions. They are pre-adjusted bracket prescriptions.

⭐ High-Yield Facts for Exam

NiTi = most flexible, alignment.
SS = stiffest, finishing/sliding.
TMA = intermediate.
Sequence: NiTi → TMA → SS.
Light continuous forces are ideal.

Archwire Materials

NiTi (Nickel-Titanium) — most flexible, lowest stiffness, shape memory and superelasticity; used for initial alignment and levelling.
TMA (Beta-titanium) — intermediate stiffness; good for finishing and springs.
Stainless steel — highest stiffness/strength; used for working and finishing stages and sliding mechanics.

Typical sequence: NiTi → TMA → Stainless steel.

Bracket Prescriptions

Pre-adjusted (straight-wire) brackets build tip, torque and in/out into the slot. MBT and Roth are common prescriptions.

Biomechanics

Light continuous forces are ideal for tooth movement. The centre of resistance vs point of force application determines tipping vs bodily movement.

Exam Tips ⭐

NiTi = flexible (alignment); SS = stiff (finishing/sliding); TMA = intermediate. Sequence NiTi → TMA → SS.

📝 Practice MCQs — Orthodontic Wires, Brackets, Biomechanics

Q1. Which archwire is used for initial alignment due to high flexibility?

A. Stainless steel

B. NiTi

C. Cobalt-chromium

D. Gold

Show Answer

✅ Answer: B

NiTi has the lowest stiffness and shape memory, ideal for alignment.

Q2. The stiffest commonly used archwire is:

A. NiTi

B. TMA

C. Stainless steel

D. Beta-titanium

Show Answer

✅ Answer: C

Stainless steel has the highest stiffness for finishing/sliding.

Q3. MBT and Roth refer to:

A. Wire alloys

B. Bracket prescriptions

C. Cements

D. Impression materials

Show Answer

✅ Answer: B

They are pre-adjusted bracket prescriptions.

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⭐ High-Yield Facts for Exam