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Published on: April 15, 2021
[Bone density changes in the apical area after rapid orthodontic extrusion of subgingivally fractured tooth]
Jun Ji1, Xiao-ping Luo, Wei Lu
1Department of Prosthodontics, Nanjing Stomatological Hospital, The Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China.
Objective:
To evaluate the bone density changes in the apical area of subgingivally fractured tooth after rapid orthodontic extrusion.
Methods:
Twelve fractured incisors in 11 patients extended 2 - 5 mm below the gingival line were selected. Two weeks after root canal therapy, the subgingival fragment was lifted up and the fracture line was brought 1.5 - 2.0 mm above the level of the gingival line by means of edgewise fixed appliance. After the extrusion completed, the tooth had been stabilized and held for 6 months. The CT Analyser software was used to measure the bone density changes in the apical area on radiographs once a month. Changes of relative value in bone density was quantitatively analyzed.
Results:
The average period of extrusion was 11 days. The relative value of bone density in the apical region was -39.6% immediately after extrusion and continuously increased afterwards. In the third month, the value (18.5%) changed most rapidly (P < 0.01).
Conclusions:
Under the continuous and proper tooth axial extrusion force, the tooth moved rapidly and steadily. The bone density in the apical area approached normal value within 3 months after treatment.
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