Healing of experimental midline osteotomies in the rat palate

An experimental study in the white rat (Sprague-Dawley) was undertaken to evaluate the frequency of fisula formation after palatal midline osteotomies as used in surgical-orthodontic "rapid-expansion" procedures. The mucosal incision was made in the palatal midline above the osteotomy region. The healing process was followed during three and six weeks in two groups of animals. In one of the groups the width of the osteotomy was one millimeter and in the other two millimeters. The frequency of fistula formation was in the larger osteotomy group higher and reached 85% after six weeks healing. The frequency of fistula formation was never less than 33%. Osteoid formation in the osteotomy region was almost nill in all cases.