目的：检验牙周再生性手术前用锥形束CT（cone beam computed tomography，CBCT）测量牙槽骨缺损高度和体积的精确性，通过比较手术前后CBCT测得的骨密度值来确定其评估牙周再生性手术疗效的检查时机。方法：对9例患者口内的10颗因牙周破坏造成的三壁骨袋进行再生性手术，术前拍摄CBCT和平行投照根尖片，测量骨缺损的高度，并利用CBCT数据测量骨缺损体积及骨缺损周边区域的骨密度。在牙周再生性手术过程中测量骨缺损的高度，并在术中充填骨蜡以获得缺损区域的体积。术后6、12、24周再次拍摄CBCT，测量原骨缺损区域的骨密度。结果：Wilcoxon检验非参数检验显示，术前用根尖片测量的骨缺损高度比术中测量结果高出（0.822±0.222）mm，差异有统计学意义（P<0.05），但术前CBCT测量结果只较术中测量结果降低（0.150±0.171）mm（P＞0.05），可见CBCT测量结果比根尖片更精确。回归分析和BlandAltman图也提示CBCT测量结果较根尖片精确。Wilcoxon检验提示，术前CBCT测量的骨缺损体积与术中测量值的差值在0.38~2.83 mm3之间，差异无统计学意义（P＞0.05）。CBCT测量的原骨缺损区域的骨密度（CT值）在再生性手术后第6、12和24周分别是原骨缺损周边区域的（0.49±0.03）倍、（0.74±0.09）倍和（1.16±0.11）倍，可见术后24周时骨再生区域骨密度更接近术前骨缺损周边区域骨密度。结论：CBCT可以在牙周再生性手术前精确测量牙槽骨缺损的高度和体积，可选择在术后24周时拍摄CBCT进行疗效评估。

Objective：To test the accuracy and credibility of cone-beam computed tomography (CBCT) on measuring the height and volume of alveolar bone defects before periodontal regeneration surgery. By comparing the bone density measured by CBCT before and after the operation, the time to evaluate the efficacy of the periodontal regenerative surgery would be determined. Methods: Periodontal regenerative surgeries were performed on three-wall bone defects of ten teeth in nine patients. The height of bone defects was measured using both periapical film of distant parallel technique and CBCT before periodontal regenerative surgery. Before the surgery, CBCT data were used to measure the volume of the bone defects and the bone density around the defective areas. The height of the bone defects was measured during pe-riodontal regeneration surgery, and the volume of the defective areas was obtained with bone wax in opera-tion. CBCT was taken 6, 12 and 24 weeks after surgery to measure the bone density in the regenerated region. Results: The Wilcoxon test showed that the height of the bone defects measured preoperatively using periapical film was (0.822±0.222) mm deeper than the intraoperative measurement results, and the difference was statistically significant (P<0.05). Whereas CBCT measurement results was (0.150±0.171) mm less than the intraoperative measurement results, without statistical significant (P＞0.05). The regression analysis and the Bland-Altman method also showed that the results of CBCT measurement were more accurate. The Wilcoxon test showed that the bone defect volume measured by CBCT preoperatively was accurate, and the difference between the preoperative and the intraoperative measurements was not statistically significant, ranging from 0.38 to 2.83 mm3 (P＞0.05). The bone density of the regenerated areas measured by CBCT was (0.49±0.03) times in the sixth week, (0.74±0.09) times in the twelfth week and (1.16±0.11) times in the twentieth week as that of the areas around the bone defects after the surgery. Conclusion: The present data suggest that using CBCT before periodontal regenerative surgery could result in accurate measurement of height and volume of al-veolar bone defects. For the purpose of evaluating the effectiveness of regenerative surgery, CBCT could be taken 24 weeks after surgery.