The purpose of this study was to investigate the effect of the pulp in replanted immature incisors on periodontal tissue. The materials were 6 beagle dogs (5-6 month old) whose maxillary left and right second incisors were extracted, replanted and physiologically (semi-rigid) splinted. Root canal treatment (pulp extirpation and calcium hydroxide filling) was performed only on the right side incisor one weekp ost-replantationO. n the same day, the splints were removed on both the left and right. The animals were given subcutaneous injections of calcein on the day of the replantation and achromycin one week and 3,5,7 weeks post-replantationD. uring a period of 15 weeks to 25 weeks postreplantation, the animals were sacrificed by perfusion under deep anesthesia 24 hours after the final labeling (calcein). The upper jaws, including incisors, were dissected and then processed into resinembedded ground sections (100μm thick). The replanted incisors and periodontal tissues of all of the sections were examined using microradiograms, fluorescent microscopy and polarizing microscopy.