不同设计和饰/釉瓷烧结对氧化锆种植全瓷冠内部和边缘适合性的影响

Influence of different designs and porcelain/glaze firing on the marginal and internal fit of implant-supported zirconia crowns

目的研究氧化锆不同设计和饰/釉瓷烧结对种植全瓷冠内部和边缘适合性的影响。方法采用Cercon计算机辅助设计及制作(CAD/CAM)系统制作3组黏结固位氧化锆种植全瓷冠,每组8颗(n=8)。A组(常规氧化锆烤瓷全冠组):常规边缘氧化锆基底冠+饰瓷,B组(360°氧化锆颈环烤瓷全冠组):360°氧化锆颈环冠边缘基底冠+饰瓷,C组(全解剖式氧化锆全冠组):解剖形态氧化锆全冠+釉瓷。饰/釉瓷烧结前和烧结后采用硅橡胶分别复制氧化锆基底冠、氧化锆全瓷冠在基台就位后的内部及边缘间隙,Micro-CT扫描硅橡胶获得内部及边缘间隙图像,测量基底冠、氧化锆全瓷冠边缘垂直间隙(MG)、冠边缘水平间隙(HMD)、肩台区间隙(CA)、轴面中点间隙(AW)、轴面和面交界处间隙(AOT)。采用SPSS 17.0软件对测量结果进行统计学分析。结果不论饰/釉瓷烧结前还是烧结后,A组HMD均大于B组和C组(P<0.05),B、C组HMD差异无统计学意义(P>0.05),A、B、C三组间MG、CA、AW、AOT均无统计学差异(P>0.05)。饰/釉瓷烧结后,A组MG较烧结前明显减小(P<0.05),A组HMD、CA、AW、AOT及B、C两组各部位间隙与烧结前相比均无统计学差异(P>0.05)。结论 360°氧化锆颈环烤瓷全冠和全解剖式氧化锆全冠的边缘适合性优于常规氧化锆烤瓷全冠,饰瓷烧结对常规氧化锆烤瓷全冠垂直间隙的影响最明显。

Objective This study investigated the influence of different designs and porcelain/glaze firing on the marginal and internal fit of three kinds of computer aided design/computer aided manufacturing （CAD/CAM） zirconia ceramic implant- supported crowns. Methods Three groups of zirconia ceramic implant-supported crowns with different designs were produced from copings by using a Cercon CAD/CAM system （n=8）. The first two groups comprised double-layer crowns （zirconia coping＋veneer） with regular （Group A） and full circumferential zirconia-collar marginal designs （Group B）. The third group was composed of anatomic single-layer zirconia crowns without cores （Group C）. Initially, the marginal and internal gaps of the copings and crowns were individually replicated by light-body silicon and then measured by micro-computed tomographyscanning before and after porcelain/glaze firing. Five mea- surements were employed： vertical marginal gap （MG）; horizontal marginal discrepancy （HMD）; chamfer area （CA）; axial wall （AW）; and axial-occlusal transition area （AOT）. Statistical analyses were performed by SPSS 17.0. Results HMD measurements in Group A were statistically higherthan those in Groups B and C （P〈0.05）, regardless of whether the values were obtained before or after porcelain/glaze firing. By contrast, the HMD measurements in Groups B and C showed no significant difference （P〉0.05）. Moreover, no differences were noted in MG, CA, AW, and AOT among the three groups （P〉0.05）. All the measurements in the three groups showed no significant change after porcelain/glaze firing （P〉0.05）, except for MG in Group A, which significantly decreased （P〈 0.05）. Conclusion The marginal fits of the double-layer crowns with full circumferential zirconia-collar and the anatomic single-layer zirconia crowns were superior to that of the double-layer crowns with regular margins. The MG of the crowns with regular margins was obviously influenced by porcelain firing.