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Interrupted orthodontic force results in less root resorption than continuous force in human premolars as measured by microcomputed tomography
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Abstract
Introduction. Root resorption is an undesirable but very frequently occurring sequel of orthodontic treatment. The aim of this study was to compare root resorption caused by either continuous (CF) or interrupted (IF) orthodontic force.
Material and methods. The study was performed on human subjects on 30 first upper and lower premolars scheduled for extraction for orthodontic reasons. During four weeks before extraction 12 teeth were subjected to either CF or IF. The force was generated by a segmental titanium-molybdenum alloy cantilever spring that was activated in buccal direction. Initially a force of 60 CentiNewton was used in both CF and IF groups, the force in the former, however, was reactivated every week for 4 weeks. There was no reactivation of force in the IF group after initial application. A morphometric analysis of root resorption was performed by microcomputed tomography and the extent of tooth movement was measured on stone casts. Furthermore, a Tartarate-Resistant Acidic Phosphatase activity (TRAP), the marker enzyme of osteoclasts and cementoclasts, was determined by histochemical method. The Mann-Whitney U test was used to compare the difference in measured parameters between treatment and control tooth groups.
Results. The number of resorption craters was significantly higher and their average volume almost twice as large in the CF compared to the IF group (p < 0.05). However, the distance of tooth displacement was similar for both groups. Cementoclasts were detected with the TRAP technique on the surface of two teeth only; both were subjected to continuous force.
Conclusions. The use of IF leads to less destruction of root structure as opposed to continuous force while the same tooth movement was achieved.
Abstract
Introduction. Root resorption is an undesirable but very frequently occurring sequel of orthodontic treatment. The aim of this study was to compare root resorption caused by either continuous (CF) or interrupted (IF) orthodontic force.
Material and methods. The study was performed on human subjects on 30 first upper and lower premolars scheduled for extraction for orthodontic reasons. During four weeks before extraction 12 teeth were subjected to either CF or IF. The force was generated by a segmental titanium-molybdenum alloy cantilever spring that was activated in buccal direction. Initially a force of 60 CentiNewton was used in both CF and IF groups, the force in the former, however, was reactivated every week for 4 weeks. There was no reactivation of force in the IF group after initial application. A morphometric analysis of root resorption was performed by microcomputed tomography and the extent of tooth movement was measured on stone casts. Furthermore, a Tartarate-Resistant Acidic Phosphatase activity (TRAP), the marker enzyme of osteoclasts and cementoclasts, was determined by histochemical method. The Mann-Whitney U test was used to compare the difference in measured parameters between treatment and control tooth groups.
Results. The number of resorption craters was significantly higher and their average volume almost twice as large in the CF compared to the IF group (p < 0.05). However, the distance of tooth displacement was similar for both groups. Cementoclasts were detected with the TRAP technique on the surface of two teeth only; both were subjected to continuous force.
Conclusions. The use of IF leads to less destruction of root structure as opposed to continuous force while the same tooth movement was achieved.
Keywords
human premolars; root resorption; continuous and interrupted orthodontic force; microcomputed tomography; TRAP; cementoclasts; reparative cementum
About this articleTitle
Interrupted orthodontic force results in less root resorption than continuous force in human premolars as measured by microcomputed tomography
Journal
Folia Histochemica et Cytobiologica
Issue
Article type
Original paper
Pages
289-296
Published online
2014-12-19
Page views
2344
Article views/downloads
2906
DOI
10.5603/FHC.a2014.0037
Pubmed
Bibliographic record
Folia Histochem Cytobiol 2014;52(4):289-296.
Keywords
human premolars
root resorption
continuous and interrupted orthodontic force
microcomputed tomography
TRAP
cementoclasts
reparative cementum
Authors
Monika Sawicka
Rossella Bedini
Piotr M. Wierzbicki
Cornelis H. Pameijer
