关键词: [关键词] 即刻种植, 下颌第一磨牙, CBCT, 牙根间隔

Abstract: Abstract：　Objective The aim of this study is to investigate the appropriate inserting position, direction and depth of immediate implantation for mandibular first molar, by using cone-beam computed tomography (CBCT), which provides a basis for preoperative digital design and clinical operation. Methods 100 CBCT images of patients who met the inclusion criteria were selected. Measuring the width of alveolar bone, buccal and lingual bone plate and interradicular septum in mandibular first molar position, analyzing its relationship with mandibular nerve canal and lingual bone concavity. Then performing the statistical analysis. Results From the mesial to the distal side, the width of the alveolar bone and the buccal bone plate gradually increased, and the width of the lingual bone plate gradually decreased. From the coronal to apical direction, the width of the interradicular septum gradually increased, with a maximum width of (5.00±1.42) mm. The distances from the mandibular nerve canal to the mesial apex, the distal apex, the distal-lingual apex and the interradicular septum are respectively (7.47±2.38) mm, (7.19±2.49) mm, (9.59±1.94) mm and (15.90±2.39) mm. From the mesial to the distal side, the maximum distances from the mandibular nerve canal to the buccal and lingual cortical bone surfaces are (6.46±1.23) mm and (2.53±0.84) mm. The angle of the mandibular lingual bone concavity is (149.67±8.30)° , and the depth of the concavity is (1.51±0.43) mm. Conclusions Before the immediate implantation of the mandibular first molar region, it is necessary to design the inserting path using CBCT images, keeping a safe distance from the mandibular nerve canal and the lingual bone concavity. If the safe distance between the apex and the mandibular nerve canal is adequate, the interradicular septum is a suitable position for implanting. Otherwise, the implant can be placed in a mesial-lingual side and inclined slightly lingually.

Key words: Key words：　immediate implantation, mandibular first molar, CBCT, interradicular septum