Scanning electron microscopy analysis of aligner fitting on anchorage attachments

  • Edoardo MantovaniEmail author
  • Enrico Castroflorio
  • Gabriele Rossini
  • Francesco Garino
  • Giovanni Cugliari
  • Andrea Deregibus
  • Tommaso Castroflorio
Original Article



The aims of the study were (1) to evaluate the fitting of three different aligners (Invisalign [Align Technology, Santa Clara, CA, USA], CA Clear Aligner [Scheu-Dental, Iserlohn, Germany] and F22 [Sweden&Martina, Due Carrare, Italy]) on anchorage attachments using scanning electron microscopy (SEM), and (2) to analyze the influence of 2 different types of resin used to build attachments on aligner fitting.


Using STL files of a patient, six resin casts were obtained and rectangular attachments were bonded on them. Conventional bulk-fill resin was used to build upper attachments while a flowable resin was used to build the lower ones. Passive aligners were adapted on each cast and then sectioned buccolingually. Microphotographs of the obtained sections were performed using a SEM and then micrometric measurements of aligner fitting on anchorage attachments were recorded.


Analyzing the overall fitting of upper arch aligners, Invisalign provided a significantly better fitting with respect to F22 (P = 0.009); differences were not significant when comparing Invisalign with CA Clear Aligner, and CA Clear Aligner with F22. Analyzing the overall fitting of lower arch aligners, F22 provided a significantly better fitting with respect to CA Clear Aligner (P = 0.008) and Invisalign (P = 0.011). The analysis showed a significantly better fitting on upper attachments, built using conventional bulk-fill resin (P = 0.034).


Invisalign, CA Clear Aligner and F22 have comparable performance in terms of fitting on anchorage attachments. Conventional bulk-fill resin provides the best fitting on anchorage attachments.


Orthodontic treatment Orthodontic tooth movement Composite resin Auxiliaries Anchor teeth 

Rasterelektronenmikroskopische Untersuchung der Paßgenauigkeit von Alignern an Verankerungsattachments



Ziele der vorliegenden Studie waren (1) die Paßgenauigkeit von drei unterschiedlichen Alignern (Invisalign [Align Technology, Santa Clara, CA, USA], CA Clear Aligner [Scheu-Dental, Iserlohn, Germany] and F22 [Sweden&Martina, Due Carrare, Italy]) an Verankerungsattachments rasterelektronenmikroskopisch zu untersuchen (REM) und (2) den Einfluss von zwei unterschiedlichen Kompositmaterialien zum Attachmentaufbau auf die Alignerpassform zu prüfen.


Aus STL Datensätzen eines Patienten wurden sechs Modelle gedruckt und mit rechteckigen Attachments versehen. Für die Attachments im Oberkiefer wurde konventionelles Bulk-Fill Komposit verwendet, für Attachments im Unterkiefer fließfähiges Komposit. Für jedes Modell wurden passive Aligner erstellt und in bukkolingualer Richtung durchtrennt. Mikrophotographien der gewonnenen Schnitte wurden rasterelektronenmikroskopisch untersucht. Die Passform der Aligner an den Attachments wurde metrisch bestimmt.


Analysiert man die Passgenauigkeit der Aligner im Oberkiefer, zeigten Aligner von Invisalign signifikant bessere Ergebnisse als F22 Aligner (P = 0,009). Unterschiede zwischen Invisalign und CA Clear Aligner bzw. CA Clear Aligner und F22 waren statistisch nicht signifikant. Betrachtet man die Passgenauigkeit der Aligner im Unterkiefer, schnitten F22 Aligner signifikant besser als CA Clear Aligner (P = 0,008) und Invisalign ab (P = 0,011). Attachments im Oberkiefer aus konventionellem Bulk-Fill Komposit waren den Attachments im Unterkiefer signifikant überlegen (P = 0,034).


Invisalign, CA Clear Aligner und F22 zeigten vergleichbare Ergebnisse in Hinblick auf die Passgenauigkeit von Alignern an Verankerungsattachments. Generell war die Passform der Aligner an Attachments aus konventionellem Bulk-Fill Komposit besser als an Attachments aus fließfähigem Komposit.


Kieferorthopädische Behandlung Kieferorthopädische Zahnbewegung Kompositharz Hilfsstoffe Ankerzähne 


Conflict of interest

E. Mantovani, E. Castroflorio, G. Rossini, F. Garino, G. Cugliari, A. Deregibus and T. Castroflorio declare that they have no competing interests.


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Copyright information

© Springer Medizin Verlag GmbH, ein Teil von Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Orthodontics, Dental SchoolUniversity of TurinTurinItaly
  2. 2.Department of Mammalian Genetics UnitHarwell CampusOxfordshireUK
  3. 3.Department of Mechanics and Aerospace EngineeringPolitecnico of TurinTurinItaly
  4. 4.TurinItaly
  5. 5.Department of Medical SciencesUniversity of TurinTurinItaly

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