The purpose of this study was to observe the effects of sodium fluoride on the bony iepair 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 ´ 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 sampl, s were drawn before and after expansion and the serum 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 osteoid 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.
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