Three-dimensional skeletal, dentoalveolar and temporomandibular joint changes produced by Twin Block functional appliance

  • Hanem Younes Elfeky
  • Mona Salah Fayed
  • Maged Sultan Alhammadi
  • Sanaa Abou Zeid Soliman
  • Dalia Mohamed El Boghdadi
Original Article



The aim of this study was to three-dimensionally analyze the net skeletal, dental, and temporomandibular joint (TMJ) treatment changes using Twin Block functional therapy in comparison to untreated subjects.

Materials and methods

The study (Twin Block) group comprised 22 female patients with skeletal Class II malocclusion due to mandibular retrusion. A total of 18 skeletal Class II untreated female subjects were included as controls. Skeletal, dental, and TMJ changes were evaluated using pre- and posttreatment/observational by cone beam computed tomography (CBCT) images. The treatment changes were compared with the growth changes observed in the control group using independent t‑tests.


Compared to the changes induced by normal growth, the effective mandibular length, ramus, and corpus lengths increased by 3.19, 3.47, and 2.69 mm (P < 0.001 for all), respectively. The maxillary and mandibular incisors inclination and position were significantly reduced and increased, respectively (P < 0.001). The maxillary first molars were significantly moved distally and intruded by 1 and 0.36 mm, respectively, while the lower first molars moved mesially and intruded by 2.18 and 0.59 mm, respectively. There was a significant change in the condylar dimensions: increase in length, width, and height by 1.28, 0.88, 1.59 on the right and by 1.60, 0.53, and 1.10 mm on the left sides, respectively. There was significant forward positioning of the right and left condyle by 1.5 and 1.3 mm, respectively.


Treatment with the Twin Block functional appliance results in significant skeletal, dentoalveolar, and condylar changes in both dimensions and positions.


Class II malocclusion Functional orthopedic appliance Twin Block Temporomandibular joint Cone beam computed tomography 

Dreidimensionale skelettale, dentoalveoläre und temporomandibuläre Gelenkveränderungen nach Behandlung mit der Twin-Block-Apparatur



Ziel der Studie war die Untersuchung skelettaler, dentaler und temporomandibulärer Veränderungen nach einer Twin-Block-Therapie im Vergleich mit einer unbehandelten Kontrollgruppe.

Material und Methoden

Die Interventionsgruppe (Twin Block) umfasste 22 Patientinnen mit skelettaler Klasse-II-Malokklusion und Unterkieferrücklage. 18 unbehandelte Klasse-II-Patientinnen dienten als Kontrollgruppe. Skelettale, dentale und temporomandibuläre Veränderungen wurden anhand von DVT-Aufnahmen evaluiert, die vor und nach Behandlung bzw. während der Behandlung angefertigt worden waren. Mittels t‑Tests für unabhängige Stichproben wurden die behandlungs- bzw. die wachstumsbedingten Veränderungen in der Interventions- und der Kontrollgruppe miteinander verglichen.


Im Vergleich mit den Veränderungen, die sich wachstumsbedingt ergeben haben, erhöhten sich die effektive Unterkieferlänge sowie die Längen von Ramus und Corpus mandibulae um 3,19, 3,47 bzw. 2,69 mm (p < 0,001 für alle). Inklination und Position der Oberkieferinzisivi verringerten sich signifikant (p < 0,001), Inklination und Position der Unterkieferinzisivi erhöhten sich dagegen signifikant (p < 0,001). Die ersten Molaren im Oberkiefer wurden signifikant um 1,0 bzw. 0,36 mm distalisiert und intrudiert, während die unteren ersten Molaren um 2,18 bzw. 0,59 mm mesialiert und intrudiert wurden. Es gab signifikante Veränderungen an den Kondylen: Länge, Breite und Höhe vergrößerten sich um 1,28, 0,88 bzw. 1,59 auf der rechten und um 1,60, 0,53 bzw. 1,10 mm auf der linken Seite. Auf beiden Seiten kam es zu einer signifikanten Vorverlagerung der Kondylen um 1,5 (rechts) bzw. 1,3 mm (links).


Die Behandlung mit einem Twin-Block-Funktionsgerät führte zu signifikanten skelettalen, dentoalveolären und temporomandibulären Veränderungen.


Klasse-II-Malokklusion Funktionskieferorthopädie Twin Block Kiefergelenk Digitale Volumentomographie 


Conflict of interest

H.Y. Elfeky, M.S. Fayed, M.S. Alhammadi, S.A.Z. Soliman and D.M. El Boghdadi declare that they have no competing interests.


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Copyright information

© Springer Medizin Verlag GmbH, ein Teil von Springer Nature 2018

Authors and Affiliations

  • Hanem Younes Elfeky
    • 1
  • Mona Salah Fayed
    • 2
  • Maged Sultan Alhammadi
    • 3
  • Sanaa Abou Zeid Soliman
    • 2
  • Dalia Mohamed El Boghdadi
    • 2
  1. 1.Department of Orthodontics and Dentofacial Orthopedics, Faculty of DentistryMinia UniversityMiniaEgypt
  2. 2.Department of Orthodontics and Dentofacial Orthopedics, Faculty of Oral and Dental MedicineCairo UniversityCairoEgypt
  3. 3.Department of Orthodontics and Dentofacial Orthopedics, College of DentistryJazan UniversityJazanSaudi Arabia

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