Clinical Study Of Orthodontic Tooth Movement Into Healed And Recent Extraction Sites

ObjectiveThe characters about maxillary canines movement style, movement rate, external apical root resorption and alveolar bone height were compared when they retracted into different healing extraction sites, to select a clinical optimal time of tooth movement.MethodsTwenty patients with dentoalveolar maxillary protrusion were treated by extracting the maxillary first premolars. By random determination, distalization of different lateral upper canines started after 1 week and 12 weeks. Every 4 weeks use a force of approximately 100g to distalize the canines. At the same time, the patient was given a high-pull headgear and instructed to wear it at least 12 hours every day. The experiment was ended when bilateral canines have contacted with the second maxillary bicuspids completely. Recordings of the canine position at the start and the end of the distalization were made from dental cast, panoramic radiograph and periapical radiography. The characters of canine distalization were estimated.Results1. The canine in the 1-week extraction side moved faster than that in the 12-week extraction side (P<0.01).2. The canines in different extraction sides both tipped a few, but there were no significant differences in the changes of the tipping angle.3. After canine distalization, there were no significant differences in the tooth rotation angle.4. External apical root resorption and alveolar bone height of the canines have no significant difference between the two groups.ConclusionsTooth extraction site healing has not much effect on the canine movement style, external apical root resorption and alveolar bone height, when it was distalization. But canine in the 1-week extraction side moved faster than that in the 12-week extraction side (P<0.01). In practice, the optimal time of tooth movement into extraction sites was about 1 week after tooth extraction.