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The Effects of Beverages and Surface Treatments on the Color Stability of 3D-printed Interim Restorations.

PURPOSE
To evaluate the color stability of 3D-printed interim restorations with different surface treatments while immersed in various staining solutions or beverages (artificial saliva, tea, coffee, and wine) for 6 months.


MATERIAL AND METHODS
An acrylic tooth was prepared for an all-ceramic full-coverage restoration. A laboratory scanner (7Series Dental Model and Impression Scanner; Dental Wings Inc, Montréal, Canada) was used to digitize the prepared abutment tooth. A virtual all-ceramic full-coverage restoration was designed on the digitized abutment tooth using a laboratory CAD/CAM software (DWOS Software 6.0; Dental Wings Inc, Montréal, Canada). Eighty abutment teeth and interim restorations were 3D-printed with tooth-colored photopolymerizing resin (NextDent Crown & Bridge A3.5; NextDent B.V., Soesterberg, Netherlands). The restorations were randomly allocated into two different groups: Polish and Optiglaze. For the polish group, interim restorations were finished and polished with aluminum oxide finishers/polishers (Enhance PoGo Complete Kit; Dentsply Sirona, York, PA). For the Optiglaze group, one layer of nanofilled, light-polymerizing protective coating (Optiglaze; GC America Inc, Alsip, IL) was then applied. The 80 printed interim crowns were divided into 4 different groups depending on where they would be immersed: Artificial saliva, coffee, wine, and tea. After the sample allocations, there were 8 experimental groups. Each group was allocated with 10 specimens. Color measurements were obtained using a digital spectrophotometer (CM-2600d Spectrophotometer; Konica Minolta Healthcare Americas Inc, Wayne, NJ) in conjunction with The CIE L*a*b* system before the immersion and 6 months after the immersion. Two-way analysis of variance (ANOVA) was used to test the effects of surface treatment, immersion liquid, and their interaction on ΔE at 6-month post-immersion. Fisher's protected least significant differences (LSD) was used as post hoc test to compare groups differences (α = .05).


RESULTS
There were significant effects of surface treatment [F(1,72) = 13.39, p = .000], immersion liquid [F(3,72) = 74.18, p = .000], and their interaction [F(3,72) = 16.33, p = .000] on ΔE at 6-month post-immersion at the α = .05 level. The polish group showed significantly higher ΔE than the Optiglaze group when immersed in coffee (p<.001) and wine (p = .015). The Optiglaze group showed significantly higher ΔE than the polish group that was immersed in artificial saliva (p<.001). The wine group showed higher ΔE than all other immersion liquid groups for both polish and Optiglaze surface treatments (p<.001 for all comparisons). ΔL* showed a reduction that was significantly higher than the 2.0 acceptability threshold in the wine-polish (p<.001) and wine-Optiglaze (p<.001) groups. ΔE showed a color change that was significantly higher than the perceptibility and acceptability thresholds for all the groups under polish surface treatment (p<0.001). ΔE also showed a color change that was significantly higher than the perceptibility and acceptability thresholds for artificial saliva, tea, and wine under Optiglaze surface treatment (p = .004).


CONCLUSIONS
3D-printed interim restorations showed significant discoloration after 6-months immersions in the artificial saliva and common beverages (including tea, coffee, and wine). Among all the chromogenic beverages, red wine caused the most significant discoloration on the interim restorations. When 3D-printed interim restorations are needed for extended intraoral service, nano-filled, light polymerizing protective coating can reduce the restoration discoloration caused by chromogenic beverages. The protective effect is most significant against coffee. This article is protected by copyright. All rights reserved.