The Chroma Study Of Alumina-zirconia Nano-composite Infiltrated Ceramic

All-ceramic restorations become the main trend of restoration materials because of the excellent esthetics effects and the recurrence to the natural teeth. But the brittleness of the ceramic limited the range and the credibility. Someone uses zirconia to enhance the intensity and toughness, however, the relative opaque core ceramic materials impact the color recurrence of the all-ceramic restorations. The main factors which influence the color of all-ceramic restorations include the color of ceramic,the transmittance of ceramic,the thickness of ceramic and the background color of the teeth.In this study, the material is made by ourselves. We measure the shifts in color with PR-650 spectrophotometer. The primary purpose of this study is to investigate the effects of thickness and different treat modes to alumina glass-infiltrated ceramic on the final color of all-ceramic restoration. The other purpose is to observe the effect of zirconia content on the color, transmittance and reflection of alumina-zirconia nano-composite infiltrated ceramic. To master the shift rules of color, transmittance and reflection of core material is the basic theory of all-ceramic esthetic effects. The results indicate as following:1) The alumina matrix has optimum porosity and lower linear shrinkage, so it may be the ideal alumina matrix for infiltrated ceramic to enhance the esthetic of the all-ceramic restoration.2)With the increase of the thickness of alumina glass-infiltrated ceramic, the value increases, the tendency of color is yellow and red. The chroma of the ceramic increases. However, the increase of the thickness leads to the decrease of the transmittance and the increase of the reflection. The relationship between the thickness of the specimen and the transmittance is negative correlation.3) The different treat mode of sinter or sandblast shows: the treat of sinter increase the L~* and decrease the transmittance, while the treat of sandblast decrease the L~* and increase the transmittance; the treat of sandblast makes the reflection decrease, but after repeating several times it increases.4) The content of zirconia makes the changes of L~*,a~* and b~* in alumina-zirconia nano-composite infiltrated ceramic. With the increase of zirconia, the L~* of specimen augments, the tendency of color is yellow and green, and the chroma augments too. The increase of zirconia leads to the decrease of transmittance and the increase of reflection. All of the changes weaken when the content of zirconia is more than 20%.