The Importance of Attachments: Why Mastering Their Placement is Crucial for Treatment Success

While clear aligners have emerged as game-changers in orthodontic treatment, they initially faced some challenges in bringing about certain movements. This goes back to the basics of aligner biomechanics. Aligners move teeth by applying controlled forces, but for optimal efficiency, they must achieve a snug fit around the tooth’s crown. The greater the contact to the surface area, the more effectively these forces can facilitate movement.

In certain instances, clear aligners alone may struggle to produce the desired results. Rotating cone-shaped teeth—such as canines and premolars—can be particularly challenging due to their tapered shape, which limits contact with the aligner and reduces force efficiency. Similarly, lateral incisors often exhibit delayed movement. Their smaller size and position between the bulkier central incisors and canines make it difficult for the aligner to wrap securely around them. This is where attachments play a crucial role. Acting like handles, attachments increase the surface area for force application and enhance the aligner’s grip on the tooth. By improving control and movement precision, attachments help to ensure that teeth track more accurately to their intended positions¹. 

What are Attachments?

Attachments are small composite extensions bonded to the tooth surface to improve aligner grip and enhance force application. By acting as anchor points, they allow aligners to exert additional pressure on teeth, making complex movements more predictable and efficient².

Clinicians typically place attachments at the beginning of treatment based on a carefully planned setup, using an attachment template provided with the aligner kit. These attachments come in various shapes, each designed for specific movements or to enhance retention.

At NDX, the following attachment types are utilized, each serving a distinct purpose:

• Horizontal Beveled Rectangular Attachments – Applied to canines, molars and premolars, these assist in retention, bucco-lingual movements and posterior extrusion.
• Vertical Beveled Rectangular Attachments – Placed on molars, premolars, canines and lower incisors, they help with mesiodistal posterior movements, lower incisor rotations, anterior axis control during mesiodistal movements, angulation corrections and aligner retention.
• Rotational Attachments – Specifically designed to aid in the rotation of premolars and canines.
• Oblique Attachments – Positioned on upper lateral incisors, these assist with rotation and extrusion or rotation alone.
• Extrusive Attachments – Primarily used for anterior tooth extrusion, these also aid in torque control in cases with significant proclination.
• Root Control Attachments – Exclusively placed on upper central incisors, these facilitate mesiodistal bodily movements and angulation corrections of the central incisors.

By strategically placing these attachments, clinicians can optimize aligner performance, helping to ensure smoother and more controlled tooth movements throughout treatment.

How are attachments placed?

The process of bonding attachments must be done meticulously to achieve accurate reproduction of the attachment shape without risk of debonding.

1. Start by inserting the aligner tray number 1 to check for proper fit. Then, rinse the attachment template with cold water and let it dry. Test fit the template on the patient's teeth, ensuring that it fits snugly until the last tooth in the arch.
2. Following that, the teeth must be thoroughly cleaned, polished, dried and isolated. It's advisable to place three attachments at a time in each quadrant for better moisture control. Next, phosphoric acid is applied for 30 seconds to etch the area, which is then rinsed for 30 seconds and dried until a frosty appearance is visible. Do not etch the whole tooth. Apply it only in the area where the attachment will be placed.
3. Apply the adhesive material and follow drying and light-curing procedures as directed by the manufacturer. A helpful tip is to apply a thin layer of separating medium, like petroleum jelly, in the attachment pocket before placing the composite for easier removal of the tray.
4. Next, carefully fill the attachment template with composite material, making sure to not over or underfill it. Any excess material going out of the attachment pocket can be removed using a plastic instrument.
5. Place the attachment template filled with composite material onto the patient's teeth. Ensure it is well adapted by applying gentle pressure using your finger or a dental instrument like a probe. Then, follow the manufacturer's instructions to light-cure the composite material, starting from the most posterior tooth where moisture control is a bit challenging.
6. Carefully remove the attachment template and inspect each attachment, then use a finishing bur to carefully remove any excess composite material. Do not over-polish as this could reduce the contact with the aligner tray. After that, use dental floss to check any remaining excess composite. Finally, insert aligner number 1 into the patient's mouth and ensure it's fully seated.

Factors Influencing Attachment Placement

Both the shape and position of attachments play a vital role in achieving precise tooth movements with clear aligners. Thus, the accurate reproduction of an attachment’s shape is of crucial importance³.

 One factor influencing the accuracy of attachment reproducibility is the template used. Those that are too flexible tend to be less accurate, and those that are too stiff are likely to result in attachment debonding during their difficult removal⁴. To strike the perfect balance, NDX Aligners provide a template that is stiff enough to maintain attachment shape integrity while remaining flexible enough for easy removal and a reduced risk of debonding.

 Another consideration is the type of composite used; those with lower viscosity may result in greater excess necessitating removal and increased chair time. Paste composite showed better accuracy in reproduction of the attachment shape under pressure⁵. 

Conclusion

Attachments play a fundamental role in enhancing the effectiveness of clear aligner therapy, optimizing force application for tooth displacement and improving aligner retention. By increasing the surface area of contact between the aligner and the tooth, they facilitate complex movements that could otherwise be challenging to achieve with aligners alone.

For attachments to function effectively, their placement and bonding must be meticulously executed. Factors such as template flexibility, composite material selection, and precise bonding protocols significantly impact their accuracy and durability. By mastering attachment placement, clinicians help to ensure better aligner fit, improved tooth tracking, and ultimately, more successful treatment outcomes. With proper attachment utilization, clear aligner therapy continues to evolve, providing patients with more reliable and effective orthodontic solutions. Get Started with NDX Aligners Today

References

1. Jedlinski, M.; Mazur, M.;Greco, M.; Belfus, J.; Grocholewicz, K.; Janiszewska-Olszowska, J. Attachments for the Orthodontic Aligner Treatment—State of the Art—A Comprehensive Systematic Review. Int. J. Environ. Res. Public Health 2023, 20, 4481. https://doi.org/10.3390/ijerph20054481
2. AlMogbel, AbdulMajeed. Clear Aligner Therapy: Up to date review article. Journal of Orthodontic Science 12(1):37, September 2023. | DOI: 10.4103/jos.jos_30_23
3. Bellocchio AM, Portelli M, Ciraolo L, Ciancio E, Militi A, Peditto M, Barbera S, Nucera R. Evaluation of the Clinical Variables Affecting Attachment Reproduction Accuracy during Clear Aligner Therapy. Materials (Basel). 2023 Oct 23;16(20):6811. doi: 10.3390/ma16206811.
4. Bellocchio AM, Portelli M, Ciraolo L, Ciancio E, Militi A, Peditto M, Barbera S, Nucera R. Evaluation of the Clinical Variables Affecting Attachment Reproduction Accuracy during Clear Aligner Therapy. Materials (Basel). 2023 Oct 23;16(20):6811. doi: 10.3390/ma16206811.
5. Sultanoğlu E, Gürel HG, Gülyurt M. The Effects of Different Attachment Types and Positions on Rotation Movement in Clear Aligner Treatments: A Finite Element Analysis. Cureus. 2024 Aug 6;16(8):e66273. doi: 10.7759/cureus.66273.
6. Bruno, G.; Gracco, A.; Barone, M.; Mutinelli, S.; De Stefani, A. Invisalign® vs. Spark™ Template: Which Is the Most Effective in the Attachment Bonding Procedure? A Randomized Controlled Trial. Appl. Sci. 2021, 11, 6716. https://doi.org/10.3390/app11156716