瓷烧结和不同数字制作技术对钴铬烤瓷冠适合性的影响

Influence of porcelain firing and different manufacturing techniques in fit of Co-Cr porcelain crowns

目的:探讨不同数字制作技术和不同扫描对象对所制作的钴铬烤瓷冠上瓷后边缘及内部适合性的影响,为判断影响钴铬烤瓷冠寿命的因素提供依据。方法:选取5颗完整上颌第一前磨牙,根据扫描预备后的离体牙、硅橡胶印模和石膏模型,将通过激光熔覆凝结(SLM)及计算机辅助设计-计算机辅助制造技术(CAD/CAM)制作的钴铬合金基底冠修复体分为扫描离体牙3D打印激光熔覆凝结(SLM)组、硅橡胶印模3D打印SLM组、石膏模型3D打印SLM组、扫描离体牙CAD/CAM切削组、硅橡胶印模CAD/CAM切削组和石膏模型CAD/CAM切削组,以传统失蜡铸造组作为对照组。进行瓷烧结,利用微计算机断层扫描技术(Micro-CT)对各组修复体边缘及内部适合性进行测量。结果:与对照组比较,扫描离体牙硅橡胶印模3D打印SLM组和CAD/CAM切削组修复体的绝对边缘差异(AMD)降低(P<0.05),硅橡胶印模3D打印SLM组修复体的边缘间隙(MG)较低(P<0.05)。与对照组比较,硅橡胶印模3D打印SLM组修复体的凹槽区(CA)和轴壁中点(AW)降低(P<0.05),扫描离体牙CAD/CAM切削组修复体的AW最小;与对照组比较,石膏模型3D打印SLM组和CAD/CAM切削组修复体的轴壁与牙合面转角的位置(AOT)及牙合面三分位点(OA)降低(P<0.05),以硅橡胶印模CAD/CAM切削组修复体的AOT和OA最小。与上瓷前比较,上瓷后修复体边缘和内部适合性普遍升高(P<0.05)。MG与制作工艺和扫描对象有关联(P<0.05),内部适合性平均数与制作工艺和扫描对象有关联(P<0.05)。结论:瓷烧结过程会影响钴铬烤瓷冠的边缘及内部适合性,选择性SLM技术制作的修复体边缘适合性优于CAD/CAM切削技术,CAD/CAM切削技术制作的修复体内部适合性较优越。

Objective：To explore the influence of different manufacturing techniques and different scanning objects in the marginal and internal fits of the Co-Cr porcelain crowns after procelain firing,and to provide the basis for judging the influencing factors of longevity of restorations.Methods：Five extracted maxillary premolar were selected.According to the prepared tooth,silicone rubber and stone die restoration models,which were fabricated by CAD/CAM and selective laser melting（SLM）,the restorations were divided into control group（traditinal casting）,tooth-SLM group,silicone rubber-SLM group,stone die-SLM group,tooth-CAD/CAM group,silicone rubber-CAD/CAM group,and stone die-CAD/CAM group.Then all the restorations were fired with the porcelain.The marginal and internal fits of the specinens were measured by micro-compated tomography（Micro-CT）.Results：Compared with control group,the AMD of restorations in tooth-SLM and CAD/CAM groups were decresed（P〈0.05）,and the MG of restorations in silicone rubber-SLM group was decresed（P〈0.05）.Compared with control group,the CA and AW of restorations in silicone rubber-SLM group were decresed（P〈0.05）,the AW of restorations in tooth-CAD/CAM group was the least;compared with control group,the AOT and OA of restorations in stone die-SLM group and CAD/CAM group were decresed（P〈0.05）,and the AOT and OA of restorations in silicone rubber-CAD/CAM were the least.Compared with before porcelain firing,the marginal fit and internal fit of restorations after porcelain firing were incresed（P〈0.05）.There was positive corrlation between the MG of restorations and fabricated techniques and scanning objects（P〈0.05）.There was positive corrlation between the average of internal fit of restorations and fabricated techniques and scanning objects（P〈0.05）.Conclusion：The porcelain firing can affect the marginal and internal fits of Co-Cr porcelain crowns.The restorations fabricated by SLM had a better marginal fit and the restorations fabricated by CAD/CAM has a better internal fit.