成長期ラットにおける下顎骨側方偏位に伴う上下顎骨の形態変化および偏位下位前後の形態回復に関する形態学的, 病理学的研究

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In orthodontic treatment, jaw deformity associated with functional malocclusion is often obserbed. It is considered critical to improve or minimize this deformity by improving functional factors in an early stage. To induce change in a short period of time, an appliance was developed for compulsory mouth opening and closing. In this study, morphological and histopathological changes were evaluated in rats after use of the sliding plate alone or in combination with the appliance, and after recovery. One hundred male Wister rats aged 6 weeks were divided into 6 groups. Group A served as untreated control group untried, Group B used sliding plate for a week. The sliding plate used in Groups B, C, and D were indentical. The mandible resulted in right deviation. In Group D, the appliance was used underanesthesia for 20 minutes (300 times/min). Group E was removed a sliding plate to Group C for 1 week. Group F was removed a sliding plate to Group D for 1 week. Upon completing experiment, based on the method digitized by Itoh et al, the maxilla was fixed to the maxillary retainer and the mandible was split into left and right, whereby they were examined under ultra soft x-ray generator. The film images were digitized into a computer via image scanner, and the points and angles were analyzed. The Results were as follows; 1. Maxillary angle measurements showed large (pre-pre') values in groups C and D, indicating left deviation of the incisive bone. Distance measurements for the mandible (kd-dg, kd-id, kd-am, and kd-pm) showed longer on the left side than on the right side in Groups C and D. In Group E, kd-dg was longer on the left side than the right Group, whereas, F was showed no difference between the right and left side. 2. Histopathological examination revealed thickening of the left condylar head cartilage on the left side compared with the right side in Groups B, C, and D. In particular, Groups C and D showed a thicker proliferation zone, maturation zone, and cartilage cell hypertrophy zone, and showed larger cells and more abundant of cartilage matrix on the left side than on the right side, and smooth transformation from cartilage to bone in the lysis zone on the left side. On the right side, similar findings were observed in Groups A and B. In Groups C and D, cells small in the proliferation, muturation, and cartilage cell hypertrophy zone, and the amount of cartilage matrix was slight compared with the left side. These cells were even smaller than those in Group A. In the lysis zone, the trabecula was thick, and the transformation from cartilage to bone was poor compared with Group A. 3. The cartilage zone on the left side in Group E and F after removal of the sliding plate, was similar to that in Group A. However, in the cartilage zone on the right side, the proliferation zone was especially thick in Group E, and the number of cells increased in the entire zone in Group F. 4. Scanning electron microscopy showed Group C and D having honeycomb arrangement of cartilage in the cartilage zone at the superior extremity of the condylar head, (and many small granules in the marginal area of the lacunae on the left side) , similar to Groups A and B. On the right side, cartilage lacunae in Groups C and D were irregular in size and often larger than those in Group A. There were few small granules in the marginal area of the lacunae, and fusion of spherical structures on the inner wall was observed. In the bone zone, the sides in Groups B, C and D were similar to that in Group A, with minimum calicified structures on collagen fibers. On the right side in Group C and D, addition of calcified structures was observed on the surface. 5. In Group E and F on the left side at the upper extremity of the condylar head, similar to that in Group A, a small amount of fine calcified structures was observed in the margin of the lacunae more so in Group E. It was suggested that a jaw deformity associated with functional malocclusion require early or
福岡歯科大学学会の論文
1996-06-30

成長期ラットにおける下顎骨側方偏位に伴う上下顎骨の形態変化および偏位下位前後の形態回復に関する形態学的, 病理学的研究

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