目的

利用锥形束计算机体层摄影术（CBCT）测量青少年下颌后牙区颊舌侧牙槽骨和基骨骨皮质的密度，探讨各部位间骨密度的大小关系。

方法

随机选择90 例（男、女各45 例）12 ～16 岁的青少年CBCT 扫描图像来测定其右侧下颌后牙区（从尖牙到第二磨牙的牙槽间隔）的颊舌侧牙槽骨和基骨骨皮质的密度。

结果

下颌颊侧牙槽骨骨皮质密度由近中向远中逐渐增加，在第一磨牙与第二磨牙间最高；下颌颊侧基骨骨皮质密度也表现出同样的规律。 颊侧基骨区骨皮质的骨密度高于颊侧牙槽骨区骨皮质的骨密度，舌侧基骨区骨皮质的骨密度高于舌侧牙槽骨区骨皮质的骨密度。 男女间骨密度差异无统计学意义。

结论

下颌后牙区颊侧骨皮质密度由近中向远中逐渐增加，下颌基骨骨皮质密度比牙槽骨骨皮质密度高。 该资料为选择种植支抗的部位和种植方法的评估提供了参考信息。

Objective

The purpose of this investigation was to quantitatively evaluate and compare the density of alveolar and basal cortical bones （buccal and lingual） in the mandibular posterior area by cone-beam computed tomography （CBCT） in adolescents.

Methods

Ninety sets of CBCT images were selected randomly，which consisted of 45 boys and 45 girls ranging from 12 to 16 years old.Cortical bone densities of alveolar and basal bones （buccal and lingual） from canine to second molar areas at right side of the mandible were measured.

Results

In mandible，the density of buccal alveolar cortical bone between canine and first premolar area was the lowest，with a progressive increase from canine to second molar area，while the density of buccal alveolar cortical bone between the first molar and the second molar area was the highest. The density of buccal basal cortical bone showed the same pattern of change as well. The density of buccal basal cortical bone was significantly higher than that of buccal alveolar cortical bone （P＜0.05），with the same as to lingual side （P＜0.05）. There was no statistical difference between boys and girls （P＞0.05）.

Conclusions

There was a progressive increase in bone density from canine to second molar areas，and the density of basal cortical bone was higher than that of alveolar cortical bone. These data might provide valuable information for selecting sites and methods to place mini-screws in the mandibular posterior area.