Side effects of twistflex retainers—3D evaluation of tooth movement after retainer debonding

Unerwünschte Nebenwirkungen von Twistflex-Retainern – eine 3-D-Evaluation von Zahnbewegungen nach Retainerentfernung



Evaluation of tooth movement after retainer debonding in retainer-associated misalignment cases.


This pilot study is based on a retrospective data analysis. Adult patients (age 25.5 ± 4.9 years) wearing fixed twistflex retainers and having visible retainer-associated misalignment were included and examined for tooth movement after retainer debonding. Orthodontic study models were taken at retainer debonding (t0) and 14 (±1) weeks later (t1). They were digitally superimposed using 2D/3D dental imaging software and tooth movement was analyzed in all three dimensions.


A total of 23 teeth (12 upper teeth: 10 incisors, 2 canines; 11 lower teeth: 7 incisors, 4 canines) were analyzed. Mean overall tipping was 1.11 ± 0.82° in the mesial/distal direction (angulation, x‑axis), 2.02 ± 1.9° in the buccal/lingual direction (inclination, y‑axis) and 1.28 ± 0.99° around the tooth axis (z-axis). Mean overall bodily movement was 0.30 ± 0.31 mm in the mesial/distal direction (angulation, x‑axis), 0.10 ± 0.13 mm in the buccal/lingual direction (inclination, y‑axis), and mean in- or extrusion 0.22 ± 0.24 mm (z-axis). Mean tipping and bodily movement were more pronounced in the upper jaw.


The present data shows that tooth movement after debonding of twistflex retainers can be expected in misalignment cases.



Evaluation von Zahnbewegungen nach Retainerentfernung in Fällen von retainerassoziierter Zahnfehlstellungen.


Diese Pilotstudie basiert auf einer retrospektiven Datenanalyse. Erwachsene Patienten (Alter 25,5 ± 4,9 Jahre) mit sichtbarer retainerassoziierter Zahnfehlstellung bei intakten Twistflex-Retainern wurden in die Studie einbezogen und hinsichtlich einer spontanen Zahnstellungskorrektur nach Retainerentfernung untersucht. Dazu wurden Gipsmodelle vom Zeitpunkt der Retainerentfernung (t0) sowie 14 (±1) Wochen danach (t1) in einer 2‑/3-D-Bildverarbeitungssoftware digital überlagert und die Zahnstellungsänderungen wurden in allen 3 Dimensionen analysiert.


Insgesamt 23 Zähne (12 Oberkieferzähne: 10 Inzisiven, 2 Eckzähne; 11 Unterkieferzähne: 7 Inzisiven, 4 Eckzähne) wurden analysiert. Die durchschnittliche Kippbewegung in beiden Kiefern betrug1,11 ± 0,82° in mesiodistaler Richtung (Angulation, x‑Achse), 2,02 ± 1,9° in bukkolingualer Richtung (Inklination, y‑Achse) und 1,28 ± 0,99° um die eigene Achse (z-Achse). Die durchschnittliche körperliche Bewegung betrug 0,30 ± 0,31 mm in mesiodistaler (Angulation, x‑Achse) und 0,10 ± 0,13 mm in bukkolingualer Richtung (Inklination, y‑Achse), die durchschnittliche In- bzw. Extrusion 0,22 ± 0,24 mm (z-Achse). Das durchschnittliche Ausmaß der Zahnbewegung war deutlicher im Oberkiefer.


Die vorgelegten Daten zeigen, dass nach dem Debonding von Twistflex-Retainern bei Zahnfehlstellungen eine Zahnbewegung erwartet werden kann.

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The authors thank Georgios Vasilakos for creating Fig. 2 and the Medical Faculties of Bonn, Jena and Aachen, Germany, for scientific support.

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Corresponding author

Correspondence to Dr. Isabel Knaup DDS.

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Conflict of interest

I. Knaup, J.R. Bartz, U. Schulze-Späte, R.B. Craveiro, C. Kirschneck and M. Wolf declare that they have no financial or nonfinancial competing interests.

Ethical standards

The study was performed in consent with the Ethics Committee of University of Aachen (EK 232-20). The study was conducted with full accordance with the ethical requirements of the World Medical Association Declaration of Helsinki (2008). Written informed consent to participate and for publication were obtained from the patients in the study.

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Knaup, I., Bartz, J.R., Schulze-Späte, U. et al. Side effects of twistflex retainers—3D evaluation of tooth movement after retainer debonding. J Orofac Orthop 82, 121–130 (2021).

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  • Orthodontic appliances, fixed
  • X‑effect
  • Retention
  • Bonded retainers
  • Orthodontic retainers


  • Festsitzende kieferorthopädische Apparaturen
  • X‑Effekt
  • Retention
  • Geklebte Retainer
  • Kieferorthopädische Retainer