• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.153-162
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• 1996

Rapid maxillary expansion is widely used for the correction of anteroposterior discrepancies, constriction of the maxillary arch, etc. This experiment was undertaken to examine the serial changes in the osteogenesis as well as the collagen fiber bundles in the intermaxillary suture during the rapid maxillary expansion treatment. Four young female dogs aged 6 to 8 months old and not showing menarche yet were used for the experiment. The maxillary impression of dogs were taken, expansion device cast and Hyrax screw soldered at the midline in the 1st premolar area. RME device was delivered to the dogs and the activation of 0.25 mm per quarter-turn was done 2 times per day for 10 days until 5 mm separation was made. Separation of the maxilla was confirmed by X-ray. The animals were sacrificed on 0, 15, 30, 60 days from the finish of maxillary separation and preparations for light microscopy and surface electron microscopy were made. The sutures were cut into frontal serial sections for examination of the histological reactions. The following results were obtained and the conclusions made. 1. The edges of the two palatal plates bordering the midpalatal suture which at the beginning of the retention period were mainly composed of compact bone, underwent extensive resorption followed by new bone formation and gradually became spongy bone rich in bone marrow which in the 60 day retention animal became the compact bone with short intermaxillary suture space. During this transformation, newly formed trabecular bone tissues were added to the original margin. 2. Throughout the expansion period, the collagen fibers underwent successive changes such as stretching, loss of polarity, and finally fibrillogenesis. Towards the end of the expansion procedure, sharpey's fiber formation in newly formed bones were observed. 3. Bony spicules were found in the initial stage of retention on occlusal topographic X-rays, which later were confirmed to have ossified. 4. Judging from the histological changes occuring during the experimental expansion, excessive expansion will cause an excessive bleeding, and retard the remodeling of intermaxillary suture. According to the above results, the bone remodeling after rapid maxillary expansion was preceded by the migration of migratory cells into the intermaxillary suture area. The bone remodeling phenomena were on-going during the 2 months retention sample.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.85-97
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• 1998

The purpose of this study was to observe the effects of sodium fluoride on the bony repair and regeneration processes after the rapid palatal expansion in the growing dogs. Eighteen dogs were divided into experimental and control groups. They were in the late mixed dentition. The rapid Palatal expansion was undertaken in all the animals($180^{\circ}$ turn/day) for ten days. The animals were sacrificed on 0, 15 and 45 days after the finish of expansion. One mg NaF/kg of body weight/day were given orally to the experimental group. Blood samples were drawn before and after expansion and the se겨m calcium, phosphate and alkaline phosphatase level were measured. The undecalcified bone section of midpalatal suture area was made, and observed under the light microscopy The results were as follows ; 1. The day after expansion, the infiltration of inflammatory cells were prominent and the new bone formation started at the edges of the two palatal plates bodering the midpalatal suture in both groups. Especially, the newly formed osteoid were very extensive and the osteoblasts lining the osteoid were very active in the experimental group. 2. At fifteen days after expansion, the active osteoblasts lining the osteold at the surface of trabecular bony spicules and active new bone formation were observed in the both groups. However, the cellular activity and new bone formation were more prominent In the experimental group. 3. At forty five days after expansion, the continuous osteoid and new bone formation and active osteoblasts were observed in the experimental group. But these phenomena were not observed in the control group. In the control group, the numerous osteoclasts were adjacent midpalatal suture and the bony remodeling process was begun. The serum alkaline phosphatase level was maintained highly in the experimental group, but decreased in the control. According to the above results, the author reached the conclusion that sodium fluoride has the stimulation effects on the osteoid production of the osteoblasts during the healing process after the rapid Palatal expansion more continuously.