| Summary: | 碩士 === 國立陽明大學 === 牙醫學系 === 103 === Purpose
To evaluate the effect of different core/veneer thickness ratio on stress distribution in implant-supported zirconia-ceramic posterior crown.
Materials and methods
Nonlinear contact finite element analysis was used to evaluate the stress distribution in zirconia-ceramic crown under axial and oblique loading. The implant-supported maxillary first molar crown was constructed with 3mm occlusal thickness. Five models with different core/veneer thickness ration were as follows: model I 0.2 (0.5 mm/ 2.5 mm), model II 0.5 (1 mm/ 2 mm), model III 1 (1.5 mm/ 1.5 mm), model IV 2 (2 mm/ 1 mm), model V 5 (2.5 mm/ 0.5 mm). The 1st principal stress and von Mises stress were analyzed to observe the effect of different core/veneer thickness ratio on stress distribution.
Results
Either under axial loading or oblique loading, the different core/veneer thickness ratio only affected the stress distribution in the core and veneer layer. The results of 1st principal stress showed that the stress dissipation decreased as the core/veneer thickness ratio increased. The stress generated by oblique loading was greater than axial loading. Under axial loading, the model V showed relatively higher maximum von Mises stress magnitude but other models had no significant difference. As for oblique loading, the model V also showed relative higher maximum von Mises stress magnitude. Besides, the model III and IV revealed relatively favorable stress magnitude in comparison with other models.
Conclusion
The different core/veneer thickness ratio in zirconia-ceramic crown had influence on the stress distribution on crown but not the implant component or supporting bone structures. Under axial loading, the core/veneer thickness ratio as 5 is unfavorable for stress distribution. The core/veneer thickness ratio with 0.2, 0.5, 1 and 2 showed no obvious difference. As for oblique loading, the core/veneer thickness ratio as 1 and 2 is relatively favorable for stress distribution.
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