Effect of Different Implant Abutment Materials on Optical Properties of Translucent Monolithic Zirconia Crowns
Date of Award
Master of Science (MS)
Purpose: The purpose of this study was to evaluate the effect of implant abutment color on the final shade of monolithic translucent zirconia crowns. The null hypothesis was that abutment color or brand of zirconia would have no effect on color of monolithic translucent zirconia crowns.Material and methods: A maxillary right central incisor implant (Nobel Replace Trilobe RP) in a dentoform model was used to mill customized abutments of titanium, gold-anodized titanium, pink-anodized titanium, and zirconium dioxide. An A2 dentin shade polymethyl methacrylate abutment was used as a control. Four types of zirconia systems (BruxZir Anterior; Glidewell Laboratories, LAVA Plus High translucency zirconia; 3M ESPE, e.max ZirCAD MT; Ivoclar, Katana Zirconia HT; Kuraray Noritake) of Y-TZP were used to make 80, monolithic CAD-CAM crowns in shade A2 with 1mm thickness (20 per group). The color measurements were made using opaque try in paste as the cementing medium. The measurements were made at the mid-facial position with a spectrophotometer using a custom positioning index for reproducibility. Color differences (∆E*ab) between the test and control specimens were calculated. The data were analyzed with two-way analysis of variance (ANOVA) and compared with the Tukey post hoc test (α= 0.05).Results: According to the 2-way ANOVA results, the type of abutment material, zirconia system, and interaction of these variables significantly influenced the ∆E values. Clinically unacceptable measurements (∆E >4.0) were observed for all translucent zirconia systems against metallic abutments except for the Katana HT group. For the zirconia systems investigated, use of titanium or gold hued titanium did not register significant color differences.Conclusion: Color differences for all zirconia systems were below clinically perceptible levels (∆E <2.5) when placed on zirconia abutments. The highest color change was observed for the pink hue titanium abutment group.