Abstract: Objective:To study the changes of multiple roots teeth in alveolar bone morphology in the implant area after immediate implantation by different depth. Methods: 44 teeth were selected from 38 patients who had been implanted for the previous multiple roots teeth. The cases were implanted from different depth in the middle of multiple roots with bone grafts and was divided into 4 groups- 0,1,2,3 mm below the bone by height of cervical border of implant neck. The CBCT images were took for immediate plant and 6 months later, reconstruct the 3-D images of plantation area and measure alveolar ridge width (5 planes), alveolar ridge width in labial and buccal (4 planes),lingual and palatal side (4 planes) with Simplant software. The morphology of alveolar bone in the planted area was analyzed statistically after immediate planting. Results: The width morphology of alveolar bone in the planted area was (1.158 0.567) mm, (0.676 0.390) mm, (0.391 0.257) mm, (0.163 0.149) mm, (0.053 0.083) mm in 5 measurement plane between immediate plant and 6 months later (P<0.01). The width morphology of alveolar bone in buccal side was (0.701 0.382) mm, (0.436 0.274) mm, (0.274 0.178) mm, (0.121 0.115) mm in 4 measurement plane (P<0.01). The width morphology of alveolar bone in lingual or palatal side was (0.448 0.308) mm, (0.233 0.170) mm, (0.119 0.119) mm, (0.041 0.056) mm in 4 measurement plane (P<0.01). The width morphology was different significantly between immediate plant and 6 months by different planting depths, The bone absorption was highest in the subosseous 0 mm group and the subosseous 1 mm group, the subosseous 2 and 3 mm group had less bone absorption (P<0.05). Conclusions: The alveolar bone width of the implanted area all decreased when multiple roots teeth were implanted immediately, and bone absorption mainly occurred in the neck of the implant; from the neck of the implant to the root, the alveolar bone absorption becomes less and less. Implantation depth of immediate implantation of multiple roots teeth should be 2 mm below bone.

Key words: [Keywords] Immediate Implant , bone resorption, CBCT