目的:探讨设置不同粘接间隙参数对CAD/CAM PMMA全冠的固位力的影响.方法:选取5颗因正畸需要拔除的第一前磨牙作为研究对象,按全冠牙体预备标准进行牙体预备.使用口腔扫描仪(CS3600)和Exo-cad软件完成全解剖PMMA全冠的设计,依照设置粘接剂间隙参数不同分为6组.距离修复体终止线2 mm内粘接间隙0μm,终止线2 mm以上粘接间隙分别设置为20μm、40μm、60μm,记为0-20组、0-40组、0-60三组;距离修复体终止线2 mm内粘接间隙20μm,终止线2 mm以上粘接间隙分别设置为20μm、40μm、60μm,记为20-20组、20-40组、20-60三组.使用椅旁切削机完成PMMA全冠制作(n=30).通过触觉-视觉表初步评估修复体的边缘适合性和稳定性;使用体式显微镜测量边缘间隙值;万能实验机进行拉伸实验检测固位力,使用SPSS 19.0统计软件对数据进行分析.结果:针对不同粘接间隙参数,PMMA的全冠平均边缘间隙均符合临床要求.其中,0-20组平均边缘间隙最大(83±6)μm,20-60组平均边缘间隙最小(37±5)μm(P<0.05),边缘间隙与粘接间隙呈负相关.不同粘接间隙参数的设置,PMMA全冠固位力存在统计学差异(P<0.05).其中,20-20组固位力最大(61±6)MPa,0-60组固位力最小(39±5)MPa(P<0.05).结论:粘接间隙设置为20～20μm时,CAD/CAM PMMA全冠修复体的固位力和稳定性可以达到满意效果.

Objective: To measure and analyze the spherical radius of Monson of normal young people in Guangdong province using cone-beam CT (CBCT), and to establish a personalized measurement method of the spherical radius of Monson to provide a reference for clinical application of Monson spherical radius in occlusal reconstruction. Methods: Sixty healthy young adults from physical examination population at Stomatology Hospital of Guangzhou Medical University [30 males and 30 females, aged (22.1±2.0) years 18-26 years) were recruited, and their CBCT were taken. Three-dimensional reconstruction of CBCT data was carried out, and the reconstructed models were fixed, traced and measured. The difference of Monson spherical radius between male and female was compared by using a single sample t-test. Results: The Monson spherical radius was (100.72±4.89) mm. The Monson spherical radius of male and female were (103.48±4.19) mm and (97.97±3.93) mm respectively. The difference between male and female was statistically significant (P<0.01). Conclusions: CBCT can be used to accurately measure the spherical radius of Monson and can be used as a reference for reconstruction of occlusal plane.

Objective:To evaluate the feasibility of the application of newly developed self-glazed zirconia crowns without veneering porcelain in the esthetic zone by following a completely digital workflow.Methods:To compare the esthetic outcomes of two patients who had been treated for esthetic restorations in the anterior maxilla.For one case,teeth were prepared with minimally invasive approach allowing for the preservation of dental pulp vitality.Monolithic self-glazed zirconia crowns with a thickness of only 0.4 mm in the labial side was prepared.For another case,teeth were prepared based on conventional preparing procedure.Two kinds of zirconia crowns were then prepared,namely monolithic self-glazed zirconia crowns without veneering porcelain and conventional laminate-structured zirconia crowns with veneering porcelain,respectively.Results:The monolithic self-glazed zirconia crowns with a thickness of only 0.6 mm in the labial side was prepared,as well as the self-glazed zirconia crowns were applying glaze on the labial surface if necessary,that can also achieve a more natural,authentic and biomimetic appearance.Conclusion:The self-glazed zirconia crowns prepared by following a completely digital workflow can obtain superior esthetic results while allowing the minimal invasive preparation and enabling the treatment of the complicated cases with high aesthetic demands.

Objective:To fabricate an all-ceramic crown which copies the morphology of preoperative tooth in one patient with only small occlusal dentin defects with completely digital design (CDD)technology,and to find a more precise and feasible solution to fix the tooth detect.Methods:The tooth treated with root canal therapy had the complete axial surface and small occlusal dentin defects.In order to keep the morphology of preoperative tooth,the digitized crown was designed with the information of preoperative tooth by oral scanning with CS3500 and using the"Biogeneric Copy"function of exocad design software,then the digitized information of the teeth was collected and transformed and the simulate zirconia crown was mode by 3D colloidal deposition technique.The patient's comfort and satisfaction were investigated by observing the morphology,the interproximal contacts,and the occlusion of crown.Results:The morphology of definitive restoration was similar to the preoperative tooth,which presented good interproximal contact and occlusion,and the patient was greatly satisfied without discomfort and foreign body sensation.Conclusion: A more accurate and personalized restoration approach can be implemented with the application of CDD to fabricate new ceramic crowns which copy the preoperative tooth.