Experiment Research Of Rapid Tooth Movement With Periodontal Ligament Distraction

Orthodontic treatment usually lasts for very long because tooth moves comparatively slowly in order to keep the tooth and its periodontal tissue healthy. Patients always expect to shorten the period of treatment so that the influence of orthodontic appliances to their appearance and sociality could be reduced to minimun. For many years, scholars home and abroad have dedicated to find out a method to accelerate tooth movement on the premise that no irreversible harms to pulp, root and periodontal tissue were produced.The method of 'periodontal ligament distraction' could accelarate tooth movement speed to a great extent. Tooth moves fast to new place under heavy distraction force. However, the long-term effects on root resorption, pulp vitality and periodontal tissue health deserve attention.Eight beagles were used in this study. The mandibular second premolars were extracted and the third premolars were used as anchorage. The first premoalrs were distalized using the method of periodontal ligament distraction on experiment side, while on control side light forces about 100g were produced with NiTi coil spring. Tooth movement was measured with a sliding caliper and root surface was observed with scanning electronic microscope (SEM). Different means of histological morphology, enzyme histochemistry, immunity histochemistry, in situ hybridization were applied to make clear the tissue rebuilding of the moved teeth in different aspect of morphology, protein...