Experimental luxation injuries in immature rat teeth

The development of an experimental model in which a standardized traumatic injury is given to dental tissues of experimental animals is necessary to understand the tissue reactions of luxated human teeth. In this study we contrived a rat molar luxation device by which bilateral upper first molars are pushed horizontally toward the palate to cause a constant amount of dislocation. The pushing force is controlled with regard to strength, direction and duration. Using this device, molars of 3‐week‐old Wistar rats weighing 45‐60 g were luxated, and damage to the pulps and periodontal tissues was evaluated histologically. Every luxated tooth had approximately equal hemorrhage, cell degeneration, and irregularity of periodontal fibers in the palatal cervical region. In the buccal cervical and in the bifurcation regions, the periodontium suffered edema and hemorrhage. The periodontal fibers in these regions were elongated and, in some areas, torn. Periodontal hemorrhage was also observed at the distobuccal root apex. The severity and distribution of the tissue injury were nearly equal in almost all of the molars. Few alveolar bone fractures or root fractures were observed. From these results, it is concluded that a standardized luxational trauma can be delivered to rat molars by the use of this experimental method.