| Objective To observe if there will be any orthodontic tooth movements at the repaired areas of rats' defective alveolar bones embedded by Perioglas and HPPA (Hydroxyl poly calcium sodium phosphate), and any statistical differences in moving distances and remodeling situations of powered periodontium contrasted with the situation on the contralateral side.Methods 44 female SPF Wistar rats (6-week-old, 190±10g weight) were randomly divided into two groups: Perioglass group and HPPA group. After general anesthesia with 2% Ketamine Hydrochloride and local infiltration anesthesia with Articaine, flap operations of mucoperiosteum were done on the mesio-areas of the maxillary right first molar. Alveolar bone defects (3mm×2mm×2mm) were made in these areas with fissure bur at low speed. Perioglass and HPPA were respectively filled into the defects of different groups. The left maxillaries served as controls. 12 weeks later after the operations, 2 rats of each group were randomly chosen and killed. Histological sections of the repaired area of both experimental side and the control side were made and observed, and the bone formation situations were compared. Orthodontic appliances were fixed onto both the left and right maxillary first molars of the remaining 40 rats, with drawing force strengthened every two weeks. All the rats were killed after 8 weeks' tooth movements (20 weeks later after after the operations). The ground sections of periodontal tissues of maxillaries with both the left and right first molars were made, and distances of maxillary first molar movements were measured. Histological sections of teeth-periodontium were made. The bone formation situations of the repaired areas of alveolar bone defect filled with different materials were observed, and the data were analyzed statistically.Results 1. In the twelfth week after operations,the areas filled with Penoglas presented uniform osseous tissues without clear boundary with normal bone tissues. However,the dentisy of the osseous tissue was lower than that of the normal bone tissues.There was some lacunae left in the Perioglas-absorbing area.New bone with lower density than normal bone formed in the defect areas treated with HPPA.The new bone was surrounded by osteoid,which had a unclear boundary with HPPA.HPPA merged with the bone.2. After the twelfth week after operations,the rats' teeth could be moved by the drawing force of the orthodontic at the alveolar bone area filled with Perioglas and HPPA.3. In the twentieth week after operations, it could be observed that uniform bone formed in the defect areas treated with Perioglas and merged with the normal bone at the defect edges. The density was higher than that in the twelfth week,but still lower than that of normal bone. The lamellar bundle bone of the newly formed osseous tissue was less than that of the normal bone but the cell conut was higher. Boundary between HPPA and the normal bone was unclear.Uniform new bone filled the defect area treated with HPPA with higher density than that of the twelfth week but lower than that of normal bone.4. In the twentieth week after operation, with vuttingdisc of the rest 40 rats, it was observed that at the area filled with Perioglas the average distance of the first molar movement (x±s) was(1.52±0.26)mm; HPPA group, distance (1.55±0.20)mm. And in the contralateral side the average distance was (1.54±0.26) mm. Pairwise comparison was used to evaluate the differences in the average first molar movement distances between all the 3 groups, but it did not show any significantly differences with q test(P>0.05).5. In the twentieth week after operation, histology slice of the rest 40 rats were observed and it was showed that at the area filled with Perioglas the peridental membrane width of the pressure area of the first molar root tip (x±s) was (58±2)μm and the tension area was (114±6)μm. And at the area filled with HPPA the peridental membrane width of the pressure area of the first molar root tip was (54±2)μm and the tension area was (116±7)μm. And on the contralateral side the peridental membrane width of the pressure area was (55±3)μm and the tension area was (119±8)μm. Pairwise comparison was used to evaluate the differences of the peridental membrane width of the pressure area and tension area of first molar root tip between all the 3 groups, but it did not show any significantly differences with q test(P>0.05).6. In the twentieth week after operation, histology slice of the rest 40 rats were observed and it was showed that in the area filled with Perioglas osteoclast count in the pressured alveolar bone of the first molar (x±s) was (8.7±0.4); in HPPA group osteoclast count (8.9±0.8); in contralateral side, (9.0±0.6). Pairwise comparison was used to evaluate the differences of the osteoclast count between all the 3 groups, but it did not show any significantly differences with q test(P>0.05).Conclusion 1. The rats' teeth can be moved normally under orthodontic force at the alveolar bone filled with Perioglas and HPPA.2. There were no significant differences of the average movement distances of a orthodontic tooth and the remodeling of powered periodontium between the side filled with materials and the contralateral side. |
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