Time-related root resorption after application of a controlled continuous orthodontic force

Area of Science:

• Orthodontics
• Dental Research
• Tissue Engineering

Background:

• Root resorption is a common side effect of orthodontic treatment.
• Understanding the factors influencing root resorption is crucial for minimizing adverse outcomes.
• Controlled application of orthodontic forces allows for investigation into cellular responses.

Purpose of the Study:

• To investigate the incidence and severity of root resorption following controlled, continuous orthodontic force application.
• To analyze the relationship between the duration of orthodontic force and the extent of root resorption.
• To identify potential individual factors contributing to root resorption during orthodontic tooth movement.

Main Methods:

• Fifty-six maxillary premolars in adolescent patients were subjected to a weekly controlled orthodontic force (50 cN).
• Contralateral premolars served as untreated controls.
• Root resorption was assessed radiographically at intervals from 1 to 7 weeks.

Main Results:

• Root resorption was observed in nearly all test teeth after one week, with significant increases in surface area and depth by week two.
• Apical root resorption reaching or exceeding halfway to the pulp was noted from the third week onwards.
• After seven weeks, test teeth exhibited over 20 times greater mean resorbed root contour compared to controls, with considerable individual variations unrelated to tooth movement.

Conclusions:

• Continuous orthodontic forces of 50 cN induce significant root resorption.
• Individual patient factors, rather than the magnitude of tooth movement, play a substantial role in the variability of root resorption.
• Further research is needed to elucidate the specific individual biological factors influencing orthodontic root resorption.