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Effect of Remodeling Root Surfaces by New Cementum Formation on Orthodontically Induced Tooth Root Resorption in Rats Open Access


Other title
Orthodontic tooth movement
Dental root surface resorption
Cyclosporine A
Low-level laser therapy
Type of item
Degree grantor
University of Alberta
Author or creator
Alsulaimani, Mahmoud A
Supervisor and department
Flores-Mir, Carlos (Department of Dentistry)
Dederich, Douglas (Department of Dentistry)
Examining committee member and department
Flood, Patrick (Department of Dentistry)
Doschak, Michael (Pharmacy)
Yen, Edwin (University of British Columbia)
Pehowich, Daniel (Department of Dentistry)
Medical Sciences-Orthodontics

Date accepted
Graduation date
Doctor of Philosophy
Degree level
Background: The etiology of dental root surface resorption associated with orthodontic tooth movement is not fully understood. However, under normal circumstances, the cementum layer covering the dental root surfaces provides a protective barrier against resorption. Objective: To investigate the effect of cementum layer remodeling, induced either by cyclosporine A (CsA) or by low-level laser therapy (LLLT), on the amount of root resorption caused by orthodontic tooth movement. Methods: Two different animal experiments were performed. The first experiment lasted two weeks and used three groups of female Sprague-Dawley (SD) rats as follows: six rats received daily 10mg/kg CsA subcutaneous injections; six rats received daily LLLT treatment delivered by gallium-aluminum-arsenide (GaAlAs) laser at an 830nm wavelength; and six rats received no treatment (control). In vivo micro-computed tomography (micro-CT) was used to analyze volumetric changes in the root hard tissue. The cementum thickness was also evaluated histologically. A follow-up split-mouth study was performed using nine female SD rats. The right side maxillary first molars received daily LLLT treatment using the same laser exposures as in the previous experiment for two weeks. The left side was not treated and served as the control. Immediately after LLLT treatment, orthodontic appliances were placed bilaterally to move the right and left molars mesially over four weeks. Ex vivo micro-CT was used to evaluate the volume of root resorption. The extent and severity of root resorption were then assessed histologically. Results: In the first experiment, the cementum was significantly thicker (P=0.019) over the root surfaces in the LLLT group compared with the control and CsA groups. The follow-up experiment showed significantly less (P=0.028) root resorption volume due to tooth movement on the LLLT side compared with the control side. This protective effect against root resorption was more, on average, on the root surfaces that showed more cementum growth in response to our LLLT treatment. Conclusion: Our LLLT treatment significantly increased the thickness of dental root cementum in rats. Moreover, remodeling of the rats’ dental root surfaces using our LLLT treatment resulted in a significant decrease in the volume of root surface resorption following application of orthodontic force.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
Alsulaimani M, Doschak M, Dederich D, Flores-Mir C. “Effect of low-level laser therapy on dental root cementum remodeling in rats”. Orthod Craniofac Res. 2015 May; 18 (2): 109-16

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