THE EFFECT OF TYPES OF ORTHODONTIC FORCE ON THE ROOT RESORPTION AND REPAIR IN RAT MOLAR

교정력 양상이 백서의 치근 흡수와 회복에 미치는 효과

  • Jang, Dong-Soo (Department of Dentistry, Graduate School, Pusan National University) ;
  • Son, Woo-Sung (Department of Dentistry, Graduate School, Pusan National University)
  • 장동수 (부산대학교 치과대학 교정학교실) ;
  • 손우성 (부산대학교 치과대학 교정학교실)
  • Published : 1994.09.01

Abstract

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

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