Effects Of Saliva And UV Aging On The Color Stability For All Ceramic Laminate Veneer

Objective Obtaining a perfect aesthetic, especially with the translucent porcelainlaminate veneers; shade of the porcelain, type of the resin cement and their long termcolor stability are important factors to achieve aesthetic success. The purpose of thestudy was to assess the effect of saliva storage and UV ageing on the final color of fullceramic laminates with different resin cement systems.Methods Fourty-two disks of standardized thickness (0.5mm), diameter (10mm) andcolor (shade A3) were prepared from Diene lithium silicate glass-ceramic (IPS e.max).Forty-two bases of standardized thickness (1.0mm), diameter (10mm) and color(translucent. Light-core Bisco) were used as the underlying structure. Initially, eachgroup(fourteen specimens) of the disks were bonded to the flat surfaces of the baseswith a thin layer of different resin cement systems (Superbond C&B bond, Sun MedicalCo.,Ltd; RelyXTMVeneer bond,3M Denta l Products; VariolinkⅡbond, Ivoclar Co.,)to ensure immobilization of the specimens (baseline). With artificial saliva andultraviolet radiation effects on the specimens, color of the ceramic specimens wasmeasured with a colorimeter Data color i5. Color coordinates L*, a*, b*were recorded.and the color differences△E were calculated meanwhile. The results were analysedstatistically with ANOVA.Results(1)After the specimens were soaked in artificial saliva for7days and30days, the L*value, a*value and b*value of the three bonding agents specimens didn’t show significant difference (P>0.05). After90days, Superbond C&B group showedsignificant difference from the other two groups （P<0.05). To make longitudinalcomparison, L*, a*, and b*value of three bonding agents all changed. The L*valuedecreased, and a*and b*value increased. The results showed significant difference (P <0.05). This reflected that in the experiment, with the increase of immersion time in threebonding agents, color change has taken place. At the time of90days,△E was1.08±0.38、0.52±0.03、0.53±0.13respectively. However, as△E<1.5, the colordifference change was not easy to be perceived by naked eyes.(2). After ultraviolet irradiation for1day,7days and13days, the L*value, a*valueand b*value all changed. L*value decreased, while a*and b*value increased. Thedifference was statistically significant change (P <0.05). Color change for SuperbondC&B became more evident after7days(△E=1.59±0.26), which could be observedvisually. But color changes for RelyXTMVeneer group and Variolink II group were little,which could be accepted clinically.Conclusions Among the three kinds of bonding agents, porcelain veneer restorationsbonded with C&B chemical curing adhesive bonding was more vulnerable to ultravioletlight discoloration than saliva storage discoloration. However, porcelain veneerrestorations bonded with RelyXTMVeneer light curing adhesives agent and Variolink IIdual-cure adhesive bonding agent, the color change were little, so they are more suitablefor thin porcelain restorations bonding, such as on Porcelain veneers.