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KMID : 0988420020140020127
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Journal of Dental Science (C.N.U.)
2002 Volume.14 No. 2 p.127 ~ p.136
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The Effect of Occlusion on the Reorganization of Periodontal Fibers during Retention Periods after Tooth Movement in Rats
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Abstract
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The purpose of this study was to evaluate the effect of occlusion on the mechanical strength of periodontal fibers during retention periods after experimental tooth movement.
In the Sprague-Dawley male rats weighing 200 g or more. The intraoral elastics was inserted into the interproximal space of upper the first and second molars. After 4th day of teeth movement, the left mandibular first, second, and third molars were extracted for differentiating the occlusal side from the non-occlusal side in the experimental groups. The intraoral elastics was removed and then light cured resin was placed in the interproximal space between the bilateral upper first and second molars following undercut was made for retention. From the day beginning retention, 7 rats were sacrified at 0, 4, 8, 12, 16, 20 days respectively. For evaluating of degree on the mechanical strength of periodontal tissue, maximal shear load of the bilateral upper first molars were measured by use of Instron Universal Testing Machine.
The results of this study were obtained as follows:
1. In the occlusal side from no retention group to 4-day, 8-day, 12-day, 16-day, and retention 20-day group as time was going maximal shear load was increased and there was statistically difference from retention 12-day group(p<0.05).
2. In the non-occlusal side from no retention group to 4-day, 8-day, 12-day, 16-day, and retention 20-day group as time was going maximal shear load was increased slightly but there was no statistically difference(p>0.05).
3. The result compared with maximal shear load between occlusal and non-occlusal side showed no statistically difference until retention 8-daygroup(p>0.05), and showed statistically difference from retention 12-day to 20-day group(p<0.05).
These results show that the occlusion had an effect on mechanical strength of the periodontal fibers during retention periods after experimental tooth movement; therefore, it is suggested that consideration of occlusion is required for the type and length of retention at the time of retention planning.
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