Effects of orthodontic force magnitude on cell apoptosis and RANKL-induced osteoclastogenesis

Studies in a rat model
  • S. KayaEmail author
  • M. Çifter
  • A. Çekici
  • V. Olgaç
  • H. İşsever
  • G. Işık
Original Article



The aim of this study was to evaluate the time course of orthodontic force-induced apoptosis and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in a rat model under light- and heavy-force conditions.


Male Wistar rats were divided into light-force (10 cN) and heavy-force (60 cN) groups (N = 28/group). Each group was divided into four time-course subgroups to evaluate all phases of orthodontic tooth movement. Mesialization appliances were placed on three united maxillary molars unilaterally and activated. Tooth movements were calculated, and periodontal ligament (PDL) widths were measured. Expression of Bax, Bcl‑2, caspase 3, caspase 9, and RANK–RANKL were assessed by immunohistochemistry. Expression levels at the PDL–alveolar bone border were compared between experimental and control groups and force groups.


The rate of tooth movement did not differ between the force groups. PDL widths were higher on the tension side in the heavy-force group in the post-lag phase. Pro-apoptotic protein Bax expression was elevated in the heavy-force group, whereas anti-apoptotic protein Bcl‑2 expression was elevated in the light-force group. RANK expression on days 7 and 21 and RANKL expression on day 21 differed between the force groups.


Evidence of orthodontic force-induced apoptosis is more robust with stronger forces than with weaker forces. Exuberant RANKL-induced osteoclastogenesis that was seen when applying a low force results from increased RANK and RANKL expression in the post-lag phase.


Orthodontic tooth movement Cell death Periodontal ligament Immunohistochemistry Osteoclastic activity 

Auswirkungen der kieferorthopädischen Kraftgröße auf Zellapoptose und RANKL-induzierte Osteoklastogenese

Untersuchungen am Rattenmodell



Ziel dieser Studie war es, den zeitlichen Verlauf der durch kieferorthopädische Kräfte induzierten Apoptose und der RANKL(„receptor activator of nuclear factor κB ligand“)-induzierten Osteoklastogenese in einem Rattenmodell unter verschiedenen Kraftbedingungen zu untersuchen.


Männliche Wistar-Ratten wurden je nach applizierter Kraft in 2 Gruppen unterteilt: geringere (10 cN) und höhere (60 cN; n = 28/Gruppe) Kräfte. Jede Gruppe wurde weiter in 4 Untergruppen unterteilt, um alle zeitlichen Phasen der kieferorthopädischen Zahnbewegung zu bewerten. Mesialisationsgeräte wurden auf 3 verblockten Oberkiefermolaren einseitig platziert und aktiviert. Zahnbewegungen wurden berechnet und die Breite des Parodontalligaments (PDL) gemessen. Die Expression von Bax, Bcl‑2, Caspase 3, Caspase 9 und RANK-RANKL wurde immunhistochemisch bestimmt. Die Expressionsniveaus an der PDL-Alveolarknochengrenze wurden zwischen Versuchs- und Kontroll- sowie zwischen den Kraftgruppen verglichen.


Die Geschwindigkeit der Zahnbewegung unterschied sich nicht zwischen den Kraftgruppen. Die PDL-Breiten waren auf der Spannungsseite in der 60-cN-Gruppe in der Post-lag-Phase höher. Die proapoptotische Protein-Bax-Expression war in der 60-cN-Gruppe erhöht, während die antiapoptotische Protein-Bcl-2-Expression in der 10-cN-Gruppe erhöht war. Die RANK-Expression an den Tagen 7 und 21 sowie die RANK-Expression an Tag 21 unterschieden sich zwischen den Kraftgruppen.


Der Evidenznachweis einer kieferorthopädischen kraftinduzierten Apoptose ist bei stärkeren Kräften robuster als bei schwächeren. Die übermäßige RANKL-induzierte Osteoklastogenese, die bei Anwendung einer geringen Kraft zu beobachten war, resultiert aus einer erhöhten RANK- und RANKL-Expression in der Post-lag-Phase.


Kieferorthopädische Zahnbewegung Zelltod Periodontalligament Immunhistochemie Osteoklastische Aktivität 



No external funding, apart from the support of the authors’ institution, was available for this study.


This work was supported by Istanbul University Research Fund, project no. 32969.

Compliance with ethical guidelines

Conflict of interest

S. Kaya, M. Çifter, A. Çekici, V. Olgaç, H. İşsever and G. Işık declare that they have no competing interests.

Ethical standards

This study was approved by the Istanbul University Ethics Committee for Animal Research (2 January 2013, 2012/177). This study adhered to the Animal Research Reporting in Vivo Experiment guidelines. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.

Supplementary material

56_2019_205_MOESM1_ESM.pdf (73 kb)
Supplementary Table 1: Means, ranges (Min minimum and Max maximum) and standard deviations (Std dvt) for periodontal ligament (PDL) width. E experimental, C control
56_2019_205_MOESM2_ESM.pdf (92 kb)
Supplementary Table 2: Means, ranges (Min minimum and Max maximum) and standard deviations (Std dvt) for apoptosis pathway protein immunopositive cells count values on the pressure side. E experimental, C control
56_2019_205_MOESM3_ESM.pdf (92 kb)
Supplementary Table 3: Means, ranges (Min minimum and Max maximum) and standard deviations (Std dvt) for apoptosis pathway protein immunopositive cells count values on the tension side. E experimental, C control
56_2019_205_MOESM4_ESM.pdf (92 kb)
Supplementary Table 4: Means, ranges (Min minimum and Max maximum) and standard deviations (Std dvt) for RANK–RANKL immunopositive cells count values. E experimental, C control


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Copyright information

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

Authors and Affiliations

  1. 1.Department of PeriodontologyOkan University Faculty of DentistryIstanbulTurkey
  2. 2.Department of PeriodontologyIstanbul University Faculty of DentistryIstanbulTurkey
  3. 3.Department of OrthodonticsIstanbul University Faculty of DentistryIstanbulTurkey
  4. 4.Department of Tumor Pathology and CytologyIstanbul University Institute of OncologyIstanbulTurkey
  5. 5.Public HealthIstanbul UniversityIstanbulTurkey

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