Repair of root resorption 2 to 16 weeks after the application of continuous forces on maxillary first molars in rats: a 2- and 3-dimensional quantitative evaluation

Gonzales, Carmen, Hotokezaka, Hotokezaka, Darenddeliler, M. Ali, and Yoshida, Noriaki (2010) Repair of root resorption 2 to 16 weeks after the application of continuous forces on maxillary first molars in rats: a 2- and 3-dimensional quantitative evaluation. American Journal of Orthodontics and Dentofacial Orthopedics, 137 (4). pp. 477-485.

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Introduction: Root resorption is a side effect of orthodontic treatment that occurs with the removal of hyalinized tissue. Studies have shown that a reparative process in the periodontium begins when the applied orthodontic force is discontinued or reduced below a certain level. However, quantitative 3-dimensional evaluation of root resorption repair has not been done. The aim of this study was to quantitatively assess the 2- and 3-dimensional changes of root resorption craters after 2 weeks of continuous mesially applied orthodontic forces of 50 g on rat molars and 2- to 16-week retention periods. Methods: We used 60 male Wistar rats (10 weeks old). Nickel-titanium closed-coil springs were used to apply 50-g mesial forces for 2 weeks to move the maxillary left first molars. The rats were randomly allocated to 6 groups. Those in the zero-week retention group were killed after force application. In the remaining 5 groups, the interdental spaces between the maxillary first and second molars were filled with resin to retain the molars. The molars were extracted after periods of retention from 2 and 16 weeks. The maxillary right molars were used as the controls. Mesial and distal roots (distobuccal and distopalatal) were examined by using scanning electron and 3-dimensional scanning laser microscopes. The surface area, depth, volume, and roughness of the root resorption craters were measured. Results: The area, depth, and volume of the craters decreased gradually and showed similar trends over the retention time, approaching a plateau at the 12th week. After 16 weeks of retention, the volumes of the resorption craters of the distobuccal and distopalatal roots reached recovery peaks of 69.5% and 66.7%, respectively. Small pits on the mesial roots showed recovery of 62.5% at the 12th week. The healing patterns in distal roots with severe resorption and mesial roots with shallow resorption had no significant differences. Conclusions: The resorption and repair processes during the early stages of retention are balanced, and most of the reparative process occurs after 4 weeks of passive retention after the application of orthodontic force. Frequent orthodontic reactivations should be avoided to allow recovery and repair of root surface damage.

Item ID: 45166
Item Type: Article (Research - C1)
ISSN: 1097-6752
Keywords: root resorption; repair; rat molar
Date Deposited: 13 Sep 2016 23:41
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110506 Orthodontics and Dentofacial Orthopaedics @ 70%
11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110320 Radiology and Organ Imaging @ 30%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920113 Oro-Dental Disorders @ 50%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920402 Dental Health @ 50%
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