The purpose of this study was to quantify the biologic effects of the tensile forces from helical springs across the maxillary incisors on the periodontal tissues of rats, 39 Sprague-Dawlely rats were divided into a control group(3 rats) and
three
experimental groups(36 rats)-group 1, pressured with a light force(50-75g), group 2, with a heavy force(250-300g) and group 3, with a heavy force(250-300g) plus laser irradiation.
Autoradiographic and histopathologic observations were performed in 12, 24, 48 and 96 hours after force application.
@ES The result were as follow :
@EN 1. Hyalinized zone of periodontal ligament began to appear at pressure side in 12 hours in group 2 and group 3 ; all decreased in 96 hours except in group 2.
2. Alveolar bone resorption began to appear in 12 hours in group 2 and group 3: Group 2 showed more resorption than group 1 and no difference to group 3.
3. Tearing of periodontal ligament ad vascular dilatation began to appear at tension side in 12 hours in all groups ; Group 2 showed more changes than group 1 and no difference to group 3 ; Decrease began to appear in 96 hours.
4. New bone formation began to appear at tension side in 12 hours and increased more and more : No differences were shown of groups
5. New capillary proliferation began to appear at pressure side in 12 hours ; The changes were the greatest in group 3, group 2, group 1, in that order.
6. Positive reaction of cells to [3H]-thymidine was the greatest in 24 hours of all groups and decreased with times ; Group 2 showed more reaction than group 1 and no difference to group 3.
KOREA J. ORTHOD 1993 ; 23(2) : 199-215.
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