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Reverse arch wire technique using undersized wires for enhanced incisor axis control during retraction: A clinical technique and case series
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Received: ,
Accepted: ,
How to cite this article: Salesse N, Hoang V, Nguyen Lu Nhat V, Luu Hai N. Reverse arch wire technique using undersized wires for enhanced incisor axis control during retraction: A clinical technique and case series. APOS Trends Orthod. doi: 10.25259/APOS_300_2025
Abstract
The Reverse Archwire (RAW) technique represents a simplified biomechanical approach that utilizes undersized rectangular archwires to control incisor inclination during en-masse retraction in extraction cases. This case series included three consecutive patients presenting with bialveolar protrusion who were treated with four-premolar extractions using conventional 0.022-inch slot MBT appliances. Initial alignment was achieved with 0.014–0.016-inch nickel–titanium archwires in combination with posterior lacebacks, followed by space closure using 0.016 × 0.022-inch or 0.017 × 0.025-inch stainless-steel archwires incorporating a reverse curve of Spee. No auxiliary anchorage devices, including mini-screws or power arms, were employed. Treatment changes were evaluated using pre- and post-treatment cephalometric analyses and superimposition. All cases demonstrated effective anterior retraction with controlled incisor inclination and preservation of vertical skeletal relationships. The mean reduction in maxillary incisor inclination was 10° relative to the sella-nasion plane, with a corresponding 5 mm decrease in U1-Nasion point A. Mandibular incisors exhibited a mean reduction of 14° relative to the mandibular plane and a 6 mm decrease in L1-Nasion point B. A stable Class I occlusion and improved soft-tissue profile were achieved in all patients. No clinically significant anchorage loss or vertical opening was observed, and treatment outcomes remained stable at 2-year follow-up. Within the limitations of a small case series, the RAW technique appears to provide predictable control of incisor inclination and effective anchorage preservation during space closure without the need for auxiliary anchorage. This approach may offer a clinically efficient and reproducible alternative for anterior control in selected extraction cases.
Keywords
Incisor control
Orthodontic biomechanics
Reverse archwire
Space closure
Torque control
Undersized archwire
INTRODUCTION
In extraction cases, many clinicians assume that reliable control of incisor torque requires slot-filling rectangular wires and/or auxiliaries such as power arms, mini screws, or anterior torquing springs.[1,2] These additions can increase appointment time, inventory complexity, and the risk of iatrogenic side effects (e.g., root resorption from heavy moments, soft-tissue irritation, and unwanted vertical changes).
With a standard straight-wire mechanic, decreasing the size of the wire cross-section leads to two effects: increased tipping or loss of incisor torque, as the play between the bracket and the wire increases, allowing freer tooth movement and deepening of the bite due to reduced wire rigidity.[3]
In classic orthodontics, this is a common side effect that is mitigated in various ways. Edgewise techniques traditionally address it by filling the slot and may employ additional wire bending and auxiliaries. However, in the Begg technique, which uses only round wires of relatively small diameter, slot-filling mechanics are not possible. Instead, torque control is achieved by curving the wire and using torquing springs,[4] Nonetheless, the results obtained are similar to those achieved with slot-filling edgewise mechanics.[5]
We describe here a simplified approach that is called the Reverse Archwire (RAW) technique [Figure 1]. The arrows in this figure represent a relative schematic force system, not the accurate force system. The accurate force system highly depends on the 3D shape of the curved wire. This method uses a single undersized rectangular wire with a reverse curve of Spee to create a moment system during space closure. The effects of leveling the curve of Spee are well documented on a full arch, and it is common knowledge that this process leads to proclination and intrusion of the anterior segment.[6] By inverting the archform, RAW has both posterior and anterior effects. In the posterior region, the curve creates a moment that counteracts the collapse of the arch and promotes more translational tooth movement during space closure. In the anterior region, the same labial and vertical intrusive forces are generated during the leveling of the curve of Spee. This produces a counterclockwise moment that counteracts the clockwise moment produced by the single-point force of the closing mechanics, thereby converting uncontrolled tipping into controlled tipping. As we describe in [Figure 1] but the force system does not always correspond to a Geometry VI configuration so clinical assessment is mandatory to adjust the curve level in the archwire. Higher curve level of the archwire might be necessary and adjustments according to each clinical scenario must be decided based on biomechanical understanding of the force system, The resulting force system is influenced by the mechanical properties of the archwire, such as stiffness and elasticity, play between bracket slot and wire This behavior differs from other systems due to variations in wire stiffness, slot play, and individual patient factors and by individual patient factors, including bone quality and root morphology. Accordingly, careful monitoring and periodic adjustment at 1–2-month follow-up visits are required.
- Yellow dot indicates the center of resistance (CR). The red arrow represents the retraction force generated by the power chain. The yellow arrow denotes a force applied through the CR, while the blue arrow illustrates the moment generated by the reverse curve archwire. For simplification, the anterior and posterior segments are conceptualized as two large teeth. (a) Illustrates the force system produced by full-arch power chain retraction in the maxillary arch. (b) Depicts the force system generated by insertion of a reverse curve archwire in the maxillary arch. (c) The resultant force system of the Reverse Archwire technique, combining the effects of retraction force and the counter-moment generated by the reverse curve. (d) The reverse curve archwire made from a normal stainless steel archwire. All force systems illustrated represent static equilibrium conditions.
The usual sequence used by the authors for an extraction case is as follows. This simplified mechanical system allows for incisor axis control and bite opening at the same time whereas torquing the wire would typically deepen the bite.[7] In three consecutive patients treated with four-premolar extractions, RAW achieved incisor axis control and maintained vertical skeletal values. And for 1–3 years follow-up post-treatment, the results remained stable.
Diagnostic and etiology
Chief complaint
Three patients presented with bi-alveolar protrusion and esthetic concerns.
Crowding
Low to moderate in both arches.
Treatment plan
Extraction of four first premolars with maximum anchorage.
Etiology
Dentoalveolar protrusion with limited envelope for non-extraction correction.
Treatment objectives
The objectives were the same for the three patients, to reduce the bi-alveolar protrusion with a controlled tipping movement of the incisors and without skeletal vertical effect.
Treatment alternatives
A non-extraction option was judged not feasible due to frequent anatomical limitations of the mandible at the level of the second molars.[8] The use of mini screws or auxiliaries was deemed unnecessary, as the RAW technique provides the counter-moment needed for anterior control while preserving maximum anchorage. A transpalatal arch or sequential retraction was not used, as studies have shown that these measures make no significant difference in anchorage outcomes.[9,10]
Treatment progress and description biomechanics of the RAW technique
Appliance design and treatment sequence (standardized protocol)
Dental extractions were performed for 1–2 months following fixed appliance bonding. The initial alignment phase was initiated using either a 0.014-inch or 0.016-inch nickel– titanium (NiTi) archwire, selected according to the severity of dental crowding. Posterior lacebacks extending from the first molars (6s) to the canines (3s) were routinely applied to limit incisor proclination and to initiate controlled space management.
After sufficient leveling permitted placement of a rectangular NiTi archwire (0.016 × 0.022-inch or 0.017 × 0.025-inch), anterior space control was implemented. When no residual anterior spacing was present, an anterior laceback from canine to canine (3s–3s) was used; conversely, a power chain was applied in the presence of anterior spacing. At this stage, incorporation of a curve of Spee in the NiTi archwire was generally unnecessary, as laceback mechanics exert relatively low vertical force and the rectangular NiTi archwire was maintained for a limited duration (approximately 1–2 months). Nevertheless, there is no biomechanical constraint precluding the introduction of a curve of Spee at this phase, and it may be applied when clinically indicated.
Following progression to stainless-steel archwires, a curve of Spee in the maxillary arch or a reverse curve of Spee in the mandibular arch was incorporated using a hollow-chop plier. Space closure was then achieved using either a full-arch power chain engaging the second molars (7s) when additional anchorage reinforcement was required or a segmented approach with a power chain extending from the first or second molars (6s or 7s) to the canines (3s), combined with an anterior laceback from 3s to 3s. The anterior laceback provided stable space control while minimizing esthetic concerns and reducing chairside time, as only posterior power chains required periodic replacement.
Throughout the space-closure phase, incisor inclination was closely monitored. In the event of incipient torque loss, corrective measures included increasing the magnitude of the curve of Spee/reverse curve of Spee or advancing to a larger-dimension stainless-steel archwire (0.017 × 0.025-inch) when a 0.016 × 0.022-inch wire had been used. These adjustments allowed maintenance of anterior torque within acceptable limits while continuing space closure.
At the completion of space closure, if further torque refinement was necessary, conventional full-slot torque mechanics were employed. These included direct torque activation of the rectangular archwire or the use of auxiliary systems such as anterior torquing springs, reinforced lacebacks, passive skeletal anchorage, or interarch elastics to stabilize the anteroposterior dimension. Incisor angulation was systematically assessed at each visit through comparative analysis of serial lateral intraoral and extraoral photographs obtained at successive stages of space closure, enabling early identification and correction of unwanted changes in incisor inclination [Figure 2].
- Side-by-side photographs taken at 2-month, 10 months intervals during space closure demonstrate that the angulation of the upper incisors remained stable, so no adjustments to the wire were necessary. In contrast, the lower incisors exhibited retroclination, prompting an increase in the curve of Spee. Notably, despite occlusal stabilization in the posterior segment, the double-curve mechanics successfully opened the bite during space closure.
All patients were treated following the same protocol. Treatment duration ranged from 22 to 28 months. Jiscop® 0.022-inch slot McLaughlin–Bennett–Trevisi (MBT) brackets were used. Extractions were performed after 1–2 months after bracket placement: four first premolars were extracted in two patients, and upper first premolars with lower second premolars in one patient.
The leveling phase lasted 5–6 months. It began with a 0.014-inch NiTi archwire and lacebacks using Jiscop® 0.2 mm stainless steel (SS) ligature wire from the first molars (6s) to the canines (3s). The lacebacks were tightened at each visit until 0.016 x 0.022-inch NiTi wire could be placed. At that point, lacebacks were continued from 6s to 3s, and an additional laceback was added from 3s to 3s to prevent space opening in the anterior segment.
The space closure phase lasted 10–12 months, depending on the patient. It began once a 0.016 × 0.022-inch SS wire with a curve of Spee in the upper arch and a reverse curve in the lower arch could be inserted. En-masse retraction was performed using full-arch powerchain. At each visit, the vertical level and angulation of the incisors were checked for signs of “incisor tipping.” If it occurred, the curve of Spee was increased and/or the wire was switched to a 0.017 × 0.025-inch SS wire.
The finishing phase lasted 7–10 months and consisted of esthetic adjustments and inter-arch mechanics. It is noteworthy that none of the patients required any specific auxiliary mechanics for torque control.
CASE SERIES
Patient 1
This patient was a male subject, 20 years and 2 months old at the start of treatment. He presented with a skeletal Class I pattern (A point, nasion, B point [ANB] 4°) and a normodivergent (mesocephalic) facial profile. He had a Class I dental relationship with normal overjet and overbite. The lips were protrusive, especially the lower. Upper incisor proclination was U1 to sella nasion (SN) 104°, and lower incisor proclination was L1 to mandibular plane (MP) 102.5°.
The treatment lasted 24 months. The four first premolars were extracted. The leveling phase lasted 6 months, space closure took 11 months, and the finishing phase lasted 7 months. Class II elastics (¼”, 3.5 oz) were used for 3 months during the finishing phase, along with some lower incisor stripping to establish a Class I occlusion [Figures 3 and 4].
- Patient 1 pretreatment intra-oral pictures, extra-oral pictures, and X-ray.
- Patient 1 Lateral cephalometric values and chart. Red: Abnormal result, Green: Normal result.Red: Abnormal result, Green: Normal result, SNA: Sella nasion point A, SNB: Sella nasion point, ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, U1: Upper central incisor, L1: Lower central incisor, NA: Nasion point A, NB: Nasion point B, MP: Mandibular plane. SD: Standard deviation.
Patient 2
This patient was a 19-year-and-5-month-old female at the start of treatment. She was transferred from another clinic after receiving a combination of lower fixed appliance therapy and an upper functional appliance. She complained of a protrusive appearance and sought orthodontic treatment for correction. She agreed to full fixed appliance therapy with the extraction of all four first premolars.
The patient presented with a skeletal Class I configuration (ANB 3.2°), a normodivergent (mesocephalic) facial pattern, and a slight Class III dental relationship. The lips were protrusive, particularly the lower. Upper incisor proclination was U1 to SN 117.6°, and lower incisor proclination was L1 to MP 99°.
This was the longest treatment among the three patients, lasting 28 months. The leveling phase lasted 6 months, space closure took 12 months, and the finishing phase lasted 10 months. During the finishing phase, inter-arch Class III elastics (¼”, 3.5 oz) were used for 2 months to establish a solid Class I relationship [Figures 5 and 6].
- Patient 2 Pretreatment intra-oral pictures, extra-oral pictures, and X-ray.
- Patient 2 Lateral cephalometric values and chart. Red: Abnormal result, Green: Normal result, SNA: Sella nasion point A, SNB: Sella nasion point B, ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, U1: Upper central incisor, L1: Lower central incisor, NA: Nasion point A, NB: Nasion point B, MP: Mandibular plane. SD: Standard deviation.
Patient 3
This patient was a 19-year and 2-month-old female at the start of treatment. She presented with a skeletal Class III tendency (ANB −0.3°) and a hypodivergent (brachycephalic) facial pattern. The lips were protrusive, especially the lower. She had a slight Class III dental relationship with normal overjet and overbite. Upper incisor proclination was U1 to SN 120°, and lower incisor proclination was L1 to MP 93°.
Treatment lasted 22 months. Two first maxillary premolars and two second mandibular premolars were extracted due to a differential anchorage requirement. The leveling phase lasted 5 months, space closure took 10 months, and the finishing phase lasted 7 months. Class III elastics (¼”, 3.5 oz) were used for 2 months during the finishing phase, along with some lower incisor stripping to establish a Class I occlusion [Figures 7 and 8].
- Patient 3 pretreatment intra-oral pictures, extra-oral pictures, and X-ray.
- Patient lateral cephalometric values and chart. Red: Abnormal result, Green: Normal result. Red: Abnormal result, Green: Normal result, SNA: Sella nasion point A, SNB: Sella nasion point B, ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, U1: Upper central incisor, L1: Lower central incisor, NA: Nasion point A, NB: Nasion point B, MP: Mandibular plane. SD: Standard deviation.
Treatment results
Patient 1
There was no significant change in skeletal values. The profile improved satisfactorily, particularly at the level of the lower lip. A solid Class I relationship was achieved bilaterally, with normal overjet and overbite. Dental protrusion was reduced [Table 1].
-
Maxilla:
U1 to SN decreased from 108.2° to 92.1° (16.1° reduction)
U1 to Nasion point A (NA) reduced from 6.35 mm to 0.53 mm (5.82 mm reduction).
-
Mandible:
L1 to MP decreased from 102.6° to 83.8° (18.8° reduction)
L1 to nasion point B (NB) reduced from 11.72 mm to 5.79 mm (5.93 mm reduction).
| Measurement | Norm (Mean±SD) | Pre-treatment | Post-treatment | Category |
|---|---|---|---|---|
| SNA (°) | 81.1±3.7 | 86.4 | 82.2 | Skeletal |
| SNB (°) | 79.2±3.8 | 84.2 | 78.4 | |
| ANB (°) | 2.5±1.8 | 2.2 | 3.8 | |
| SN-MP (°) | 32.0±5.0 | 35.2 | 36.3 | |
| FMA (°) | 25.0±4.0 | 29 | 27.6 | |
| U1 – SN (°) | 105.3±6.6 | 108.3 | 92.2 | Dental |
| U1 - NA (mm) | 4.0±3.0 | 6.4 | 0.5 | |
| L1 – NB (mm) | 4.0±2.0 | 11.7 | 5.8 | |
| L1-MP (°) | 90.0±5.0 | 102.6 | 83.8 | |
| UL – E line (mm) | 0±2 | 3.6 | −3.6 | Soft tissue |
| LL – E line (mm) | 0±2 | 7.8 | 0.8 |
ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, IMPA: Incisor mandibular plane angle, L1: Lower central incisor, LL: Lower lip, MP: Mandibular plane, NA: Nasion point A, NB: Nasion point B, SNA: Sella nasion point A, SNB: Sella nasion point B, U1: Upper central incisor, UL: Upper lip, E-line: Ricketts, SD: Standard deviation.
Superimposition analysis showed that in both the maxilla and mandible, controlled tipping occurred with a very slight intrusive effect. A limitation of patient 1 is the relatively low posttreatment U1–SN and L1–MP values, which may limit generalizability, as the case was managed with orthodontic camouflage despite an initial indication for orthognathic surgery; however, the 3-year follow-up demonstrated stable dental and skeletal outcomes [Figure 9].
- Patient 1 post-treatment intra-oral pictures, extra-oral pictures, and X-ray.
Patient 2
There was no significant change in skeletal values. The profile improved satisfactorily, particularly at the level of the lower lip. A solid Class I relationship was achieved bilaterally, with normal overjet and overbite. Dental protrusion was reduced [Table 2].
-
Maxilla:
U1 to SN decreased from 117.6° to 108.9° (8.7° reduction)
U1 to NA reduced from 10.82 mm to 5.26 mm (5.56 mm reduction).
-
Mandible:
L1 to MP decreased from 99° to 85° (14° reduction)
L1 to NB reduced from 13.28 mm to 5.81 mm (7.47 mm reduction).
Superimposition showed controlled tipping in both jaws, with a very slight intrusive effect. In the mandible, an extrusion of 0.5 mm of the first molars occurred, resulting in:
An increase in SN–MP from 35° to 36° (1° change)
An increase in FMA from 25.5° to 27.5° (2° change).
Both values remained within one standard deviation of their respective normative ranges [Figure 10].
| Measurement | Norm (Mean±SD) | Pre-treatment | Post-treatment | Category |
|---|---|---|---|---|
| SNA (°) | 81.1±3.7 | 86.2 | 86.0 | Skeletal |
| SNB (°) | 79.2±3.8 | 83.0 | 83.0 | |
| ANB (°) | 2.5±1.8 | 3.2 | 3.0 | |
| SN – MP (°) | 32.0±5.0 | 35.8 | 35.2 | |
| FMA (°) | 25.0±4.0 | 29.2 | 27.3 | |
| U1 – SN (°) | 105.3±6.6 | 117.6 | 108.9 | Dental |
| U1 – NA (mm) | 4.0±3.0 | 10.8 | 5.3 | |
| L1 – NB (mm) | 4.0±2.0 | 13.3 | 5.8 | |
| L1 – MP (°) | 90.0±5.0 | 99.1 | 85.1 | |
| UL – E line (mm) | 0±2 | 2.7 | −0.3 | Soft tissue |
| LL – E line (mm) | 0±2 | 6.5 | 1.2 |
ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, IMPA: Incisor mandibular plane angle, L1: Lower central incisor, LL: Lower lip, MP: Mandibular plane, NA: Nasion point A, NB: Nasion point B, SNA: Sella nasion point A, SNB: Sella nasion point B, U1: Upper central incisor, UL: Upper lip, E-line: Ricketts, SD: Standard deviation.
- Patient 2 post-treatment intra-oral pictures, extra-oral pictures, and X-ray.
Patient 3
There was no significant change in skeletal values. The profile improved satisfactorily, particularly at the level of the lower lip. A solid Class I relationship was achieved bilaterally, with normal overjet and overbite. Dental protrusion was reduced [Table 3].
-
Maxilla:
U1 to SN decreased from 119.9° to 111.9° (8.0° reduction)
U1 to NA reduced from 10.61 mm to 6.03 mm (4.58 mm reduction).
-
Mandible:
L1 to MP decreased from 93.3° to 82.6° (10.7° reduction)
L1 to NB reduced from 7.06 mm to 1.83 mm (5.23 mm reduction).
Superimposition showed controlled tipping and translation in both arches, which explains why the reduction in angulation was slightly lower than in the other two cases, while the linear retraction remained comparable [Figure 11].
- Patient 3 post-treatment intra-oral pictures, extra-oral pictures, and X-ray.
| Measurement | Norm (Mean±SD) | Pre-treatment | Post-treatment | Category |
|---|---|---|---|---|
| SNA (°) | 81.1±3.7 | 85.5 | 84.9 | Skeletal |
| SNB (°) | 79.2±3.8 | 85.7 | 84.9 | |
| ANB (°) | 2.5±1.8 | −0.3 | 0.0 | |
| SN–MP (°) | 32.0±5.0 | 28.3 | 28.6 | |
| FMA (°) | 25.0±4.0 | 22.0 | 22.8 | |
| U1 – SN (°) | 105.3±6.6 | 119.9 | 112.0 | Dental |
| U1 – NA (mm) | 4.0±3.0 | 10.6 | 6.0 | |
| L1 – NB (mm) | 4.0±2.0 | 7.1 | 1.8 | |
| L1 – MP (°) | 90.0±5.0 | 93.3 | 82.7 | |
| UL – E line (mm) | 0±2 | 1.7 | −1.9 | Soft tissue |
| LL – E line (mm) | 0±2 | 8.5 | −1.0 |
ANB: A point, nasion, B point, FMA: Frankfort mandibular plane angle, IMPA: Incisor mandibular plane angle, L1: Lower central incisor, LL: Lower lip, MP: Mandibular plane, NA: Nasion point A, NB: Nasion point B, SNA: Sella nasion point A, SNB: Sella nasion point B, U1: Upper central incisor, UL: Upper lip, E-line: Ricketts, SD: Standard deviation.
Follow-up
Post-treatment photographs taken at debond and at the 1–3 years retention follow-up demonstrate excellent stability in all three patients. The retention protocol consisted of a removable clear retainer (TriStar® 1 mm), worn full-time (24 h/day) during the 1st year, followed by night-time wear only thereafter.
Patient 1: The treatment result is stable after 3 years of follow-up [Figure 12]
Patient 2: The treatment result is stable after 1 year’s follow-up [Figure 13]
Patient 3: The treatment result is stable after 3 years of follow-up [Figure 14].
- Patient 1 after 3-year follow-up.
- Patient 2 after 1 year follow-up.
- Patient 3 after 3-year follow-up.
DISCUSSION
Key finding
The RAW technique enabled effective control of incisor angulation during en-masse retraction using a single undersized rectangular wire. This approach produced results comparable to those typically achieved by either filling the slot or using auxiliaries for torque control
Biomechanical considerations
The reverse curve of Spee incorporated into an undersized rectangular stainless-steel archwire generates a counter-moment that mitigates anterior bowing during space closure while maintaining vertical control. Although undersized archwires may reduce torque expression, selective use of curvature, wire dimension progression, and auxiliary torque adjustments allows adequate control of incisor inclination in appropriately selected cases. This biomechanical configuration enables anterior control with minimal reliance on compliance-dependent auxiliaries.
Using an undersized wire offers significant clinical and chairside advantages over more conventional methods. Clinically, in the event of a bracket failure, the smaller wire often allows a new bracket to be repositioned without requiring a full re-leveling of the arch. As a result, such failures do not substantially increase treatment time. In contrast, when using a slot-filling wire, a failed bracket frequently necessitates a re-leveling phase, as exact repositioning is difficult. This often makes reinsertion of the wire either impossible or possible only with force levels that risk another debonding. This can extend treatment time by up to 1 month per bracket failure.[11,12] In the RAW system, torque is not expressed through bracket prescription. This makes the technique relatively insensitive to bracket brand or torque specification, if 0.022-inch slots are used. There is no need to select between low-, medium-, or high-torque brackets, and mixing different bracket brands is entirely feasible. During rebonding, only the vertical height and mesiodistal angulation need to be controlled, both of which are relatively easy to assess visually. Torque control, on the other hand, is not easily managed visually. The authors have used this technique for over a decade and have never found bracket brand or prescription to be a limiting factor; all systems have proven effective in most clinical situations.
One counterintuitive mechanical advantage of RAW is that not filling the slot can be beneficial. A 0.016 × 0.022 SS wire in a 0.022-inch slot provides approximately 40° of play in most brackets, and even more in some brands. In contrast, a 0.019 × 0.025 wire offers only about 15° of play.[13,14] As a result, the RAW system does not express any torque unless active steps are taken such as anterior wire bending or using torquing springs. Conversely, large slot-filling wires can and will express torque even when unintended if tooth anatomy and bracket positioning dictate it.[15] This is especially problematic because the clinician often realizes unwanted torque only after its effects are visible.
By design, RAW induces only tipping or controlled tipping by default. This makes it particularly safe from a periodontal perspective, as torquing teeth beyond the bony envelope is mechanically impossible without active intervention by the practitioner. This safety is further supported by evidence that alveolar bone remodeling occurs primarily near the crown, not at the apex.[16-18]
The most significant mechanical complication that can occur during space closure is the loss of torque. However, this is easily corrected, either by increasing the curve of the wire (if still in the active retraction phase), torquing the anterior segment of the wire, or using torquing springs.
The Asian population has a 3–5 times higher prevalence of skeletal Class III patterns.[19,20] This skeletal configuration is generally associated with thinner alveolar bone in the anterior region.[21,22] Despite this anatomical predisposition, loss of torque during space closure is relatively rare and has occurred only a few times in the authors’ experience. Importantly, it is not considered a clinical problem. Historically, extraction spaces were routinely closed by tipping the incisors, with angulation corrected in a subsequent phase, a standard approach in the Begg technique. This sequence has not been shown to cause iatrogenic effects. Alternative approaches, such as straight archwire mechanics combined with interarch elastics or power arms, may also be effective in controlling incisor position during space closure. However, these methods often rely on patient compliance or additional auxiliaries. In contrast, the RAW technique offers a simplified, compliance-independent biomechanical approach that may reduce treatment complexity while maintaining adequate anterior control in selected cases.
Another theoretical mechanical advantage of RAW lies in its lower friction. Because the wire does not fill the slot and has a wider range of play, RAW is a lower-friction system compared to full slot-filling mechanics. In theory, this should result in a faster rate of space closure, as suggested by laboratory studies.[23,24] However, the only available clinical study found no statistically significant difference.[25] Nonetheless, the concept remains compelling and has become a core selling point of bidimensional techniques.[26,27] In the authors’ clinical experience, treatment duration for extraction cases using RAW such as those presented here falls within the average range reported in the literature.[28-30] While lower posterior friction has not resulted in shorter treatment time, it has not caused any delays either, thanks to the system’s efficient control of incisor angulation. This eliminates the need for additional time to correct the incisor axis post-retraction.
The RAW technique may be particularly useful in clinical settings where treatment simplicity, reduced chair time, and avoidance of skeletal anchorage are desired. Careful case selection and continuous monitoring of incisor angulation remain essential to ensure predictable outcomes.
CONCLUSION
Across the three extraction cases with bialveolar protrusion, the RAW technique demonstrated consistent control of incisor inclination, effective anchorage preservation without the use of skeletal anchorage, and stable vertical skeletal relationships. Favorable occlusal and skeletal outcomes were maintained at the 2-year retention follow-up. Within the limitations of this case series, RAW represents a clinically efficient and reproducible biomechanical option for anterior control during space closure.
Acknowledgment:
We thank the patient for providing informed consent for this report and Professor Kwangchul Choy for his valuable contributions to the manuscript, particularly his biomechanical insights shared through personal communication.
Ethical approval:
Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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