Abstract:

BACKGROUND: The thickness of ceramic materials plays a crucial role in the reappearance of veneer restorations. Due to the limited space for the construction of porcelain veneer, it is difficult to cover the abutment tooth color, and the final color after restorations is achieved through the overlapping of prosthetic restorations color and abutment tooth color. In recent years, there is little evidence on the effect of veneer materials on the color.
OBJECTIVE: To evaluate the color matching of porcelain veneer restorations with different ceramic materials to shade tab. 
METHODS: Fifteen veneer restorations were fabricated by three ceramic materials (VITA Mark II, Ivoclar E.max LTCAD and Ivoclar E.max CAD Multi, A2 shade). Veneer restorations were controlled at the thickness of 0.6 mm. The color parameters of veneer restorations were measured by Olympus Crystaleye against the natural color shade resin material substrate. The color differences were calculated between veneer restoration and shade tab (A2 shade) at the cervical, central and incisal sections, respectively. The color differences (?E values) were statistically analyzed using a one-way analysis of variance.
RESULTS AND CONCLUSION: The color value of E.max CAD LT block was the closest one among the three 
blocks to the standard shade guide. The results of one-way analysis of variance for the ?E values showed that, there were significant differences between the cervical sections of the veneer restorations and the shade guide  (P < 0.05). At the cervical sections, the ?E values between three kinds of blocks with the standard shade guide showed significant differences (P < 0.05); the differences were also significant in L values at the central and incisal sections, a values at the incisal sections and b value at the shoulder sections (P < 0.05). Our findings indicate that, there are significant differences in the color of porcelain veneer restorations with different ceramic materials to shade tab. The difference is also found among the three sections of the veneer restorations. In the clinical application, the final prosthesis color effects should be noted, which can change by surface staining and bonding technology.

Key words: computer-aided design, dental porcelain, dental prosthesis, biocompatible materials