# Archwire Sequence in Treatment

> Archwire sequence in BDS Orthodontics: NiTi aligning wires, levelling, steel working wires, Begg three stages and finishing bends explained for exams.

- Canonical URL: https://prepelephant.com/topics/bds/orthodontics/archwire-sequence-treatment
- Exam / course: BDS · Subject: Orthodontics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Archwire Sequence in Treatment", PrepElephant, https://prepelephant.com/topics/bds/orthodontics/archwire-sequence-treatment

## Direct answer

Fixed-appliance treatment moves through phases, and the archwire sequence encodes them: light, flexible, large-range nickel-titanium wires (typically 0.012-0.016 inch round) align and level the crowded arch first; progressively larger and stiffer wires — finishing the levelling and reverse-curve application where the curve of Spee must be flattened — hand over to the rectangular stainless steel working wire (classically 0.019 x 0.025 inch in a 0.022 slot) that carries space closure, torque and sliding mechanics; and treatment closes with light round or braided wires for settling and detail bends. The logic is the wire-property map in clinical order — springback first when the arch is a ruin, stiffness second when force must be delivered precisely, gentleness last when millimetres matter. Begg technique runs the same narrative in three named stages on round 0.016 Australian wire: stage one aligns and opens the bite with anchor bends, stage two closes space, stage three uprights and torques with auxiliaries.

## What you must remember

- **Phase one — alignment:** light NiTi (0.012-0.016 inch) engages displaced teeth with the plateau force of superelasticity; ligation of every bracket and patience outrank force.
- **Phase two — levelling and coordination:** larger NiTi or round steel flattens the curve of Spee (a reverse curve can be bent into steel), and arch form is coordinated between the arches before rectangular wires.
- **Phase three — working:** rectangular steel 0.019 x 0.025 in the 0.022 slot gives stiffness for sliding space closure, torque control and stability; undersizing the wire in the slot deliberately leaves second-order play that the prescription tolerates.
- **Phase four — finishing and settling:** ideal arch form checked, individual bends (artistic bends, torque adjustments) placed in TMA or lighter steel, then light round or braided/multistranded wires or vertical elastics settle the cusps.
- **Slot compatibility:** in a 0.018 slot the working rectangle is smaller (classically 0.017 x 0.025) — always state wire and slot together.
- **Begg stages:** stage I (alignment, overjet and overbite correction with anchor bends on 0.016 round high-tensile wire), stage II (space closure), stage III (root uprighting and torque with uprighting springs and torquing auxiliaries).
- **Force continuity principle:** every wire change should keep force light and continuous — the sequence is graduated, never a jump from 0.012 NiTi to full-dimension steel.

## Following one arch through the sequence

A 14-year-old extraction case with 6 mm of lower crowding walks the ladder. At bond-up, 0.014 NiTi threads every bracket; over eight weeks the rotations unwind and the displaced canine aligns without the heavy forces that invite hyalinisation and root resorption. Levelling follows with 0.016 NiTi and then 0.016 steel, the reverse curve bent into the steel stage where the deep curve of Spee must flatten; the arch form is coordinated to the maxilla. First premolars are removed and the 0.019 x 0.025 steel working wire enters, passive for a visit, then active tiebacks or elastomeric chain close the spaces by sliding along it — the wire's stiffness resisting deflection, its smoothness reducing friction. As spaces close, first-order bends correct a rotated molar, a small torque adjustment is placed, and the last month runs a 0.016 braided steel or light round wire with short vertical elastics to seat the occlusion. Four wire families, each promoted exactly when its dominant property is needed — that is the whole concept in one patient.

## How the exam frames the sequence

Theory papers ask either the stages of edgewise treatment with the wires for each, or the Begg three stages with their auxiliaries — the strongest answers tie each stage to the wire property that justifies it. Vivas probe the working wire dimensions in each slot (0.019 x 0.025 in 0.022; 0.017 x 0.025 in 0.018) and the reason for undersizing: play that the straight-wire prescription is designed around. Indian clinical conventions state the MBT-style sequence explicitly in case presentations — light NiTi, rectangular NiTi, rectangular steel, finishing — and examiners reward naming the wire sizes with the slot. A favourite MCQ asks which wire opens the bite in Begg stage one (0.016 round high-tensile Australian wire with anchor bends), and which phase uses braided or light round wires (settling and finishing).

## Frequently asked questions

### Which wire begins treatment and why?

A light round nickel-titanium wire, typically 0.012-0.016 inch, chosen for its springback and light continuous plateau force that aligns displaced teeth without overwhelming the periodontal ligament.

### What is the classical working wire in a 0.022 slot?

A 0.019 x 0.025 inch rectangular stainless steel archwire, stiff enough for sliding space closure and torque control while retaining designed play in the slot.

### How is the curve of Spee levelled?

By progressively stiffer wires with a reverse curve of Spee bent into the steel stage, or by nickel-titanium wires pre-formed with the reverse curve, distributing the levelling force across the arch.

### Name the three stages of Begg technique.

Stage one — alignment, overjet reduction and bite opening with anchor bends; stage two — space closure; stage three — root uprighting and torque with auxiliaries.

### Why finish with light round or braided wires?

To let the occlusion settle elastically into intercuspation with vertical elastics and permit final artistic positioning bends without the stiffness that would lock small errors in place.