Force magnitude and duration effects on amount of tooth movement and root resorption in the rat molar

Gonzales, Carmen, Hotokezaka, Hitoshi, Yoshimatsu, Masako, Yozgatian, Joseph H., Darendeliler, M. Ali, and Yoshida, Noriaki (2008) Force magnitude and duration effects on amount of tooth movement and root resorption in the rat molar. Angle Orthodontist, 78 (3). pp. 502-509.

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Objective: To test the hypothesis that there is no difference in the effect of different continuous moderate to very heavy forces on root resorption or amount of tooth movement.

Materials and Methods: In the study, 10, 25, 50 and 100 g mesial force were applied to the maxillary first molars of rat using nickel titanium closed-coil springs for 3 days, 14 days, and 28 days. The molars were extracted and the surface areas of the root resorption craters were measured using scanning electron microscope. The depths of the root resorption craters were measured using a threedimensional laser scanning microscope. Tooth movement of the maxillary first molar was measured in relation to the maxillary second molar on digitized lateral cephalometric radiographs.

Results: Three days after force application, the tooth movement was not proportionally related to force magnitude. However, 14 days of force application resulted in significantly more tooth movement in the 10, 25, and 50 g force groups than in the 100 g force group. A force application of 10 g produced significantly more tooth movement at 28 days than all the other three force applications. The largest and deepest resorption craters were observed in the disto-buccal root followed by distopalatal, middle-buccal, middle-palatal, and mesial root. Root resorption and tooth movement increased over time from 3 to 28 days. As heavier forces were applied, greater root resorption occurred.

Conclusion: The hypothesis is rejected. The light mesially oriented forces, as applied in this study, produced more tooth movement and less root resorption compared with heavier forces.

Item ID: 45160
Item Type: Article (Research - C1)
ISSN: 1945-7103
Keywords: root resorption; heavy force; depth; area; laser scanning microscope; SEM
Funders: Ministry of Education, Science, Sports, and Culture of Japan
Date Deposited: 06 Oct 2016 00:28
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110506 Orthodontics and Dentofacial Orthopaedics @ 90%
11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110320 Radiology and Organ Imaging @ 10%
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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