IADR Abstract Archives
Study of press-on-zirconia technique using newly developed lithium disilicate glass-ceramics
Objectives: In recent years, lithium disilicate (LDS) based glass-ceramic restorations have been widely used due to better mechanical properties as compare to feldspathic ceramics. However, adaptive cases of LDS restorations are limited up to 3-unit bridges without molar teeth. In order to overcome this disadvantage, LDS press-on-zirconia technique is proposed. The purpose of this study was to evaluate the compatibility between newly developed lithium disilicate glass-ceramics and zirconia.
Methods: Zirconia frameworks of 3-unit bridges were prepared and crown shapes were waxed up on it. Newly developed LDS press material, Initial LiSi Press (GC Corp), was heat-pressed on zirconia frameworks and devested according to normal procedures (POZ group). As control group, specialized porcelain was veneered on zirconia framework (PFZ group). Restorations were placed in a furnace at 105 ° C for 30 minutes and quenched in ice water. After the restorations were checked for cracks or flaking, the undamaged specimens were heated up using steps of 15 ° C and same tests as above were repeated until the failure of restorations. The interface between ziroconia and Initial LiSi Press was examined by SEM observation and EDS analysis.
Results: POZ showed cracks in 2 samples at 165 ° C and cracks in 1 sample at 180 ° C. In PFZ group, cracks were observed in 1 sample at 150 ° C and 2 samples at 165 °C.
It has been confirmed that POZ has the thermal shock resistance equal to or higher than conventional PFZ technique. Significant gaps and composition gradient were not detected between zirconia and Initial LiSi Press.
Conclusions: Initial LiSi press can be pressed on zirconia, and it is available expected that producing a prosthetic appliance that combines aesthetic and strength.
Methods: Zirconia frameworks of 3-unit bridges were prepared and crown shapes were waxed up on it. Newly developed LDS press material, Initial LiSi Press (GC Corp), was heat-pressed on zirconia frameworks and devested according to normal procedures (POZ group). As control group, specialized porcelain was veneered on zirconia framework (PFZ group). Restorations were placed in a furnace at 105 ° C for 30 minutes and quenched in ice water. After the restorations were checked for cracks or flaking, the undamaged specimens were heated up using steps of 15 ° C and same tests as above were repeated until the failure of restorations. The interface between ziroconia and Initial LiSi Press was examined by SEM observation and EDS analysis.
Results: POZ showed cracks in 2 samples at 165 ° C and cracks in 1 sample at 180 ° C. In PFZ group, cracks were observed in 1 sample at 150 ° C and 2 samples at 165 °C.
It has been confirmed that POZ has the thermal shock resistance equal to or higher than conventional PFZ technique. Significant gaps and composition gradient were not detected between zirconia and Initial LiSi Press.
Conclusions: Initial LiSi press can be pressed on zirconia, and it is available expected that producing a prosthetic appliance that combines aesthetic and strength.