[The study of rapid maxillary expansion in the laboratory animals]

Forty rabbits were used to study the rapid maxillary expansion. The widths of the dental arch and the base arch were measured. The histologic changes of the palatal medius suture tissue and periodontal tissue of the anchorage teeth after various degree of rapid maxillary expansion were observed. The result indicated that the width of dental arch and base arch were increased by expansion force. The increasing width of the dental arch almost were caused by the expansion of the medius suture chiefly. The stronger the force, the more the expansion of the palatal medius sutures, but this kind of force might cause the damage of the anchorage tooth periodontal tissue and delay the repairing and remodeling response of the tissue. The medius suture tissue has stronger endurance to the heavy expansion force.