Influence of porcelain firing and different manufacturing techniques in fit of Co-Cr porcelain crowns / 吉林大学学报(医学版)

ABSTRACT

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.