Effect of framework material on the color of implant-supported complete-arch fixed dental prostheses

Abstract

Statement of problem. The effect of framework material on the color of implant-supported complete-arch fixed dental prostheses is unclear. Purpose. The purpose of this in vitro study was to investigate the effect of different framework materials on the final color of implant-supported complete-arch fixed dental prostheses. Material and methods. A master model was used to simulate an edentulous maxilla with 4 implants. A screw-retained complete-arch resin prototype with a 1.5-mm cut back on the facial surfaces of the teeth was fabricated. The master model and resin prototype were scanned and digitized with a laser scanner. A computer-aided design (CAD) model was constructed using software and used for milling titanium (Ti) and zirconia (Zir) frameworks. Four Zir frameworks were milled from solid presintered Zir blocks, and 4 Ti frameworks were milled from solid Ti blocks. The Zir frameworks were then sintered. To simulate gingiva on the Zir and Ti frameworks, feldspathic porcelain was layered on the facial aspects of the teeth (except for the molars) and glazed. Color coordinates (L*, a*, b*) of anterior teeth and gingiva on both Zir and Ti frameworks were measured with a spectroradiometer, and color differences (CIEDE2000) were calculated between Zir and Ti frameworks using the CIEDE2000 formula. The color coordinates of the teeth and gingival porcelain on the frameworks were analyzed using an ANOVA (alpha=.05). Results. For the teeth, the 3-way ANOVA revealed a significant interaction for material, tooth, and coordinate (P=.014), material and coordinate (P<.001), and tooth and coordinate (P<.001). For the gingival porcelain, the 2-way ANOVA revealed a significant interaction between material and coordinate (P<.001). The L* values of the teeth and gingival porcelain on Zir frameworks were statistically different from those on the teeth and gingival porcelain on the Ti frameworks (P<.001). The maxillary right central incisor on the Ti frameworks had a significantly higher a* (P=.013) and b* value (P<.001) than those on the Zir framework. The color differences (CIEDE2000) of teeth and gingival porcelain between Ti and Zir frameworks were 6.6 and 8.6, respectively. Conclusions. Feldspathic porcelain layered for teeth and gingiva was lighter on Zir frameworks than on Ti frameworks. Porcelain on the facial aspects of teeth was redder and yellower on Ti compared with Zir. Gingival porcelain on Zir was yellower than that on Ti. The color of layering porcelain on the teeth and gingival areas was significantly different when different frameworks (Ti or Zir) were used.