Color Stability of PMMA Resins for Complete Denture Produced by CAD/CAM and 3D Printing Technologies: An In Vitro Study.

Purpose: The purpose of this in vitro study was to evaluate the effect of a staining solution on color stability of resins for complete dentures produced with conventional and digital technologies.

Materials and methods: 60 resin specimens were prepared and divided in 6 groups of 10 specimens each: Probase Hot (PH, Ivoclar AG), IvoBase CAD (IBC, Ivoclar AG), Ivotion Dent (ID, Ivoclar AG), Ivotion Dent Multi (IDM, Ivoclar AG), Dima Print Denture Base (DPDB, Kulzer), and Dima Print Denture Teeth (DPDT, Kulzer). One surface of each specimen was polished following the manufacturer's instructions. The CIELab color differences were evaluated before and after immersion for 28 days in a coffee solution and measured as DE using two dental spectrophotometers. One specimen for each group was selected for SEM analysis at baseline and at 28-day.

Results: Data analysis was performed by Kruskal-Wallis test and post-hoc Dunn test for comparison. Regarding specimens analyzed with VITA Easyshade, IDM white zone (polished and unpolished) scored higher (∆E= 0.87 and ∆E = 1.15 respectively). All milled samples (IBC, ID, IDM pink zone), scored significantly higher as compared to PH and DPDT. Regarding Spectroshade, IDM pink zone performed better, regarding both polished and unpolished specimens (∆E=1.57 and ∆E=2.07 respectively). ID demonstrated a statistic higher color stability compared to PH and DPDT. Regarding the SEM analysis any differences in surface morphology was observed between baseline and 28-days immersion analyses.

Conclusions: Color stability is significantly higher in resin specimens obtained with digital technologies as compared to conventional resin specimens after immersion in a staining solution.