Study On The Adjustment Of The Expansion Coefficient Of Dental Zirconia Ceramic With The Negative Thermal Expansion Material Zr₂WP₂O₁₂

ObjectiveTo avoiding chipping of the veneering porcelain layered on zirconia frameworks,more researches are focused on the surface modification of zirconia,instead of focusing on an important internal factor-mismatch of coefficients of thermal expansion between zirconia and veneering porcelain.In this research,commercial zirconia（Cercon Smart ZrO₂）was composited with the negative thermal expansion material(Zr₂WP₂O₁₂)innovatively.The Cercon Smart ZrO₂/Zr₂WP₂O₁₂2 composite ceramic was prepared to adjust the coefficient of thermal expansion of Cercon Smart ZrO₂.As a result,chipping of the veneering porcelain will decrease with lessening of the residual thermal stress caused by thermal incompatibility of zirconia core and veneering porcelain in all-ceramic restorations in clinical.MethodsThe negative thermal expansion material Zr₂WP₂O₁₂2 and Cercon Smart ZrO₂/Zr₂WP₂O₁₂2 composite ceramic were synthesized by solid-state reaction method.XRD,DIL and SEM were used to test and analysis the composite.And mechanical properties and physical properties of the composite were investigated.As a comparison,the same mechanical properties of domestic zirconia which is a well-known inland brand,were investigated too,to evaluate the clinical applicability of the composite.ResultsThe main contents are as follows:1.Using the solid-state reaction method,we prepared ZWP with high purity.2.Cercon Smart ZrO₂/Zr₂WP₂O₁₂2 composite ceramic were synthesized by solid-state reaction method successfully.XRD showed that the two materials did not react with each other.SEM showed the particles of the Cercon Smart ZrO₂ and Zr₂WP₂O₁₂2 were uniform size and smaller diameter.The gaps between the two were small,and the two materials formed the sosoloid.3.The coefficients of thermal expansion of Cercon Smart ZrO₂/Zr₂WP₂O₁₂composite decreased with the Zr₂WP₂O₁₂2 content increasing in a small range(The content of Zr₂WP₂O₁₂<3 wt%).4.When the content of Zr₂WP₂O₁₂2 was 2 wt%,the physical properties and mechanical properties of the composite was best and it can meet the clinical requirements theoretically.Its thermal expansion coefficient was 9.6×10^-6/℃,between Cercon Smart ZrO₂ and veneering porcelain.Conclusions1.The negative thermal expansion material Zr₂WP₂O₁₂2 and Cercon Smart ZrO₂/Zr₂WP₂O₁₂2 composite ceramic can be synthesized by solid-state reaction method.2.The negative thermal expansion material Zr₂WP₂O₁₂2 can adjust the thermal expansion coefficient of Cercon Smart ZrO₂ effectively.The coefficients of thermal expansion of Cercon Smart ZrO₂/Zr₂WP₂O₁₂2 composites are between Cercon Smart ZrO₂ and veneering porcelain.3.The content of Zr₂WP₂O₁₂2 has a great influence on the physical properties and mechanical properties of Cercon Smart ZrO_2.When the content of Zr₂WP₂O₁₂2 was 2wt%,the mechanical properties of the composite was best and it can meet the clinical requirements theoretically.