Precise, simple and fast aligner treatment

Dr Chang Pi-En

Dr Ravindra Nanda

Tue. 23. June 2026

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In response to increasing patient demand for comfort and aesthetics in orthodontic treatment, aligner treatment has grown rapidly. Over the past two decades, aligners have primarily been manufactured using thermoforming techniques. This approach imposes limitations due to the material properties and production methods. For instance, the aligner trim line may lift or lose adaptation to the tooth surface during treatment, uneven aligner thickness may occur, orthodontic forces may concentrate on the incisal third and block out may be necessary in undercut areas to ensure a proper path of insertion and removal of the aligner.^1–4 Consequently, to deliver the planned orthodontic forces for tooth movement, resin attachments often need to be bonded, and patients may be instructed to use aligner seaters to help seat the aligners fully.⁵

In recent years, the Shape Memory Aligner (Graphy), crafted from innovative materials, has revolutionised conventional treatment approaches and expectations. True to its name, this aligner features shape memory properties. At oral temperatures, it continuously returns to its original shape, applying gentle and consistent orthodontic forces to move the teeth.^{4, 6, 7} Designing and printing physical dental models for thermoforming is no longer required. From the treatment plan set-up, tooth movement staging and aligner design are performed using software, and the aligners are then produced directly via 3D printing. Aligner thickness can be specified overall and then adjusted in defined areas, and margin line height can also be adjusted according to individual case requirements before printing.⁸ Compared with traditional thermoformed aligners, the overall manufacturing process is more streamlined.

The perfect fit and individualised design of Shape Memory Aligners enable more precise tooth movement and allow for reduction of the use of attachments for treatment.^{9, 10} This article presents the use of Shape Memory Aligners to treat a case of anterior spacing with crossbite without any attachments.

Figs. 1a–c: Initial extra-oral photographs.

Fig. 1b

Fig. 1c

Case presentation

A 28-year-old female patient presented with complaints of anterior diastema, anterior crossbite and lower lip protrusion. Clinical examination and imaging were performed after consulting with the patient, including intra-oral and extra-oral photographs, radiographs and an intra-oral scan.

The initial extra-oral photographs showed a straight lateral profile and lower lip protrusion (Figs. 1a–c), and the intra-oral photographs showed a Class I molar relationship and an anterior crossbite (Figs. 2a–c). Approximately 6 mm of cumulative spacing was present between the maxillary right central incisor and the left canine (Fig. 2d). Approximately 10 mm of cumulative spacing was observed in the mandibular anterior area (Fig. 2e). The Bolton ratio of the anterior teeth was 83%, corresponding to the maxillary tooth size deficiency of 2 mm, which was within the acceptable limits. The panoramic radiograph showed that the maxillary left second molar had been replaced with an implant and that the four maxillary premolars had undergone root canal treatment and been restored with crowns (Fig. 3). In addition, a periapical lesion at the maxillary right first premolar was observed, but it was asymptomatic and would thus be monitored by the endodontist during orthodontic treatment. Cephalometric analysis showed that the ANB angle was –2.8°, consistent with a Class III skeletal pattern (Fig. 4). The lower lip was positioned 2 mm behind the Ricketts’ E-line, and the upper lip was positioned 10 mm behind the Ricketts’ E-line. Given the implant and endodontically treated premolars, the stable occlusal relationship of the posterior teeth and the satisfactory soft-tissue profile, the patient agreed for treatment to focus on anterior space closure and correction of the anterior crossbite. Considering the marked anterior spacing and the limitations of the alveolar bone, the first phase of treatment was to focus on correcting the anterior crossbite. The patient was informed that some space might remain around anterior part. Further examination of the dental and alveolar conditions would determine whether to continue closing the space.

Fig. 2a–e: Initial intra-oral photographs.

Fig. 2b

Fig. 2c

Fig. 2d

Fig. 2e

Fig. 3: Initial panoramic radiograph.

Fig. 4: Initial cephalometric radiograph.

Treatment

The intra-oral scan file was exported as an STL file to DirectAlignerDesigner software (Graphy), which was used for the treatment plan set-up, during which staging, steps and aligner design (trim line, thickness, etc.) were determined (Fig. 5). Each step was limited to maximum movement of 0.3 mm and maximum angle adjustment of 3°. The aligners were designed with a straight 2 mm extended trim line (Fig. 6) for better angulation and torque control without attachments.¹¹

After set-up of the treatment plan, the aligners were printed using TA-28 Shape Memory Aligner resin (Graphy) and the UBEE 3D printer (UNIZ Technology). Residual resin was removed using a centrifuge (Tera Harz Spinner, Graphy) for 6 minutes. The supports were then removed, and the aligners were placed in Tera Harz Cure (Graphy) for post-polymerisation under nitrogen. Before delivery to the patient, each aligner underwent a quality test by boiling in 100 °C water. If no issues were detected, the aligners were then polished and cleaned in an 80˚C ultrasonic bath (Figs. 7a–h).

The patient was instructed to wear the aligners for at least 20 hours per day and wore each for seven days. In addition, the patient was instructed to immerse the aligners in warm water daily for 30–60 seconds and to pay close attention to maintaining good oral hygiene and keeping the aligners clean.

Fig. 5: DirectAlignerDesigner, for tooth segmentation, treatment plan set-up, staging and steps, and aligner design.

Fig. 6: Straight 2 mm extended trim line.

Fig. 7a: Manufacturing workflow for Shape Memory Aligners: intra-oral scan.

Fig. 7b: Treatment plan set-up and aligner design.

Fig. 7c: Resin selection.

Fig. 7d: 3D printing of the aligners.

Fig. 7e: Centrifugation to remove residual resin.

Fig. 7f: Post-polymerisation under nitrogen.

Fig. 7g: Final quality check in 100 °C water.

Fig. 7h: Polishing and cleaning in an ultrasonic bath.

Discussion and conclusion

The first phase of treatment for this case involved 28 steps (Figs. 8a–e), and minor anterior spacing in the mandible remained. The intra-oral photographs after the first phase were consistent with the treatment plan set-up (Figs. 9a–e). The objective for the second phase of treatment was to close the remaining space while controlling the torque of the mandibular anterior teeth. The pressure points were placed at the cervical third area from the mandibular right to left lateral incisors (Fig. 10a). This approach has been reported to effectively maintain and control the tooth crown and root torque, maintain anterior root torque and enable controlled torque adjustment.¹² Additionally, buttons were attached to the aligners for Class III elastic (Fig. 10b).

Figs. 8a–e: Final position set-up for the first phase of treatment.

Fig. 8b

Fig. 8c

Fig. 8d

Fig. 8e

Figs. 9a–e: Intra-oral photographs after the first phase of treatment.

Fig. 9b

Fig. 9c

Fig. 9d

Fig. 9e

Fig. 10a: Pressure points at the cervical third of the labial inner surface of the aligner.

Fig. 10b: Buttons on the aligners for Class III elastic.

The final intra-oral photographs demonstrated the anterior space closure and a stable occlusion (Figs. 11a–e). The extra-oral photographs showed that the profile had remained straight and that the previously protruding lower lip had improved owing to the retraction of the mandibular anterior teeth (Figs. 12a–c). In total, there were 40 steps, including the maintenance steps.

Shape Memory Aligners exhibit similar properties at oral temperature to nickel–titanium wire,¹³ providing consistently gentle orthodontic force. At warm temperatures, the material softens, making it easier for patients to put on and take off the aligners. Because of this characteristic, blocking out can be minimised, and the aligner can cover more tooth area, resulting in excellent fit (Figs. 13a–j). Moreover, the straight 2 mm extended trim line provides more precise orthodontic force and achieves good tooth movement control.^{11, 14} Precise delivery of orthodontic forces to move teeth can shorten the treatment duration dramatically. Owing to these advantages of the material and design, good anterior tooth angulation and torque control were achieved in the case presented even though no resin attachments were used.

Figs. 11a–c: Final extra-oral photographs.

Fig. 11b

Fig. 11c

Figs. 12a–e: Final intra-oral photographs.

Fig. 12b

Fig. 12c

Fig. 12d

Fig. 12e

Fig. 13a: Comparison of fit between a thermoformed PETG aligner and a 3D-printed Shape Memory Aligner. The thermoformed PETG aligner shows trim line fit.

Fig. 13b: The Shape Memory Aligner demonstrates good fit.

Fig. 13c: Edentulous area without block out shows poor adaptation of the thermoformed PETG aligner.

Fig. 13d: Edentulous area with snug fit of the SMA without block out.

Fig. 13e: The thermoformed PETG aligner has uneven aligner thickness between the anterior and posterior.

Fig. 13f: The Shape Memory Aligner has uniform thickness.

Fig. 13g: Comparison of fit between a thermoformed PETG aligner and a 3D-printed Shape Memory Aligner. The thermoformed PETG aligner shows poor fit at the incisor.

Fig. 13h: The Shape Memory Aligner shows good fit at the incisor.

Fig. 13i: The thermoformed PETG aligner shows poor fit at the cervical third.

Fig. 13j: The Shape Memory Aligner shows good fit at the cervical third.

Furthermore, Shape Memory Aligners provide smaller but stable orthodontic force compared with thermoformed aligners and maintain their physical and chemical properties even after one to two weeks of wear.^{15, 16} This also leads to reduced side effects during treatment.¹⁷ In the case presented, the mandibular anterior teeth underwent much retraction; however, the posterior teeth as anchorage teeth did not tip mesially during anterior teeth retraction. The crown and root angulations were maintained, preserving a stable occlusal relationship.

Unlike traditional aligner systems, the 3D-printed Shape Memory Aligner system allows for phased treatment. There is no need to give patients all aligners at once, potentially reducing environmental pollution.¹⁸ Moreover, the system offers greater flexibility, allowing for adjustments to treatment plans or other designs based on the patient’s condition.

From the perspectives of both clinicians and patients, this new generation of direct 3D-printed aligners improves treatment efficiency, convenience and patient comfort. Understanding the characteristics, advantages and limitations of various materials and applying them in clinical treatment enables better-informed material selection and simpler, improved clinical applications.

Editorial note:

The list of references can be found here. This article was published in aligners—international magazine of aligner orthodontics vol. 5, issue 1/2026.