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. 2020 Jul-Aug;25(4):85-100.
doi: 10.1590/2177-6709.25.4.085-100.sar.

Space closure using aligners

Ricardo Martins Machado  1
Affiliations

Space closure using aligners

Ricardo Martins Machado. Dental Press J Orthod. 2020 Jul-Aug.

Abstract
in English, Portuguese

Introduction: Due to the search for more aesthetic and comfortable alternatives to perform orthodontic treatments and to the great technological development, orthodontic aligners have assumed great importance. More and more complex treatments have been carried out with these appliances without, however, having all aspects involved in their use being studied in depth. Its biomechanical planning requires different approaches than those used in fixed orthodontics, as the force systems involved in movements, responses and side effects are distinct, and the professional must be prepared when opting for the technique.

Objective: The objective of this article is to perform an evaluation of the force systems created on the space closure with aligners, its characteristics, and problems, as well as make some suggestions to overcome the difficulties inherent to its use.

Conclusion: Space closure with aligners is possible, but depends on the correct selection of the patient, in addition to requiring the proper planning of the applied forces. The use of auxiliary resources and overcorrections to address the deficiencies of the aligner systems should always be considered. Digital planning should be used as a map of the force systems that will be applied, and not just as a marketing tool, keeping in mind that determining the objectives and the way to achieve them is the responsibility of the orthodontist, and that treatment plans must be individualized for each situation, following appropriate biomechanical precepts.

Introdução:: Devido à busca por alternativas mais estéticas e confortáveis para realizar tratamentos ortodônticos e ao grande desenvolvimento tecnológico, os alinhadores ortodônticos assumiram uma grande importância. Tratamentos cada vez mais complexos vêm sendo realizados com esses dispositivos sem que, no entanto, sejam estudados em profundidade todos os aspectos envolvidos na sua utilização. Seu planejamento biomecânico requer abordagens diferentes da Ortodontia fixa, pois os sistemas de forças envolvidos nas movimentações, respostas e efeitos colaterais são distintos, e o profissional deve estar preparado ao optar por essa técnica.

Objetivo:: O objetivo deste artigo é fazer uma avaliação dos sistemas de forças envolvidos no fechamento de espaços com alinhadores, suas características e problemas, bem como apresentar algumas sugestões para contornar as dificuldades decorrentes de seu uso.

Conclusão:: O fechamento de espaços com alinhadores é possível, mas depende da correta seleção do paciente, além de exigir o adequado planejamento das forças aplicadas. O uso de recursos auxiliares e sobrecorreções para suprir as deficiências dos sistemas de alinhadores deve ser sempre considerado. O planejamento digital deve ser usado como um mapa dos sistemas de forças que serão aplicados, e não apenas como ferramenta de marketing, tendo em mente que a determinação dos objetivos e da maneira de atingi-los é de responsabilidade do ortodontista e que os planejamentos devem ser individualizados para cada situação, seguindo preceitos biomecânicos adequados.

PubMed Disclaimer

Conflict of interest statement

The author reports no commercial, proprietary or financial interest in the products or companies described in this article.

Figures

Figure 1
Figure 1. Gartner’s Hype Cycle for new technologies.
Figure 2
Figure 2. Patient presenting diastemas with exaggerated overbite, good posterior intercuspation and good incisors exposure - example of a situation where what seems to be simple for planning with fixed orthodontics becomes a complex treatment to be performed with aligners, due to the limitations of the technique.
Figure 3
Figure 3. Examples of the difference in points of application of forces between fixed appliances and plastic aligners during intrusion (A). The brackets and wires system push teeth toward the wire (B) while aligners pull the teeth to the desired direction (C).
Figure 4
Figure 4. Examples of attachments: (A) passive or retention, (B) optimized for extrusion and (C) optimized for root inclination. The optimized attachments show active surfaces for specific movements.
Figure 5
Figure 5. Examples of the great variety of attachments and resources existing in the Invisalign system, which is only one of the many options available.
Figure 6
Figure 6. Force diagram showing the bow effect that happens during the anterior segment retraction with aligners, causing intrusion of the middle segment, mesial inclination of molars and extrusion with lingual tipping of the incisors.
Figure 7
Figure 7. Female patient, 24 years of age, with bimaxillary protrusion and severe crowding on both arches, who chose to be treated with four first premolars extraction and compensation with aligners.
Figure 8
Figure 8. Situation at the end of the first aligners sequence. The curve of Spee was deepened with incisors extrusion and mesial inclination of molars and posterior open bite.
Figure 9
Figure 9. Force system planned for the second set of aligners.
Figure 10
Figure 10. Final photographs of the patient, after the second set of aligners.
Figure 11
Figure 11. Final panoramic and cephalometric radiographs with superimpositions.
Figure 12
Figure 12. A) Patient after SARPE, starting treatment with aligners. B) Tracking loss due to excessive mesial inclination of the crowns of the incisors. C) Divergent roots. D) Power arms placed to be used along with the aligners. E) Detail of active power arms. F) Improvement of tracking. G) By the end of the aligner set (a new set of aligners was planned then for better finishing).
Figure 13
Figure 13. Clinical evolution of a reciprocal space closure, from initial condition (A); to the end of the first set of 51 aligners (B); after the second set of 16 aligners (C); and the final result, after the last sequence of 21 aligners.
Figure 14
Figure 14. Final panoramic, initial and final radiographs, with cephalometric superimpositions.
See this image and copyright information in PMC

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