The Effect of Cement Shade on the Optical Properties of Additively Manufactured Permanent Crown Materials.

Objectives: To investigate the effect of cement shade and printing parameters on the optical properties of additively manufactured (AM) permanent crown materials.

Methods: Two AM crown materials (Bego VarseoSmile Crown Plus and Formlabs Permanent Crown) and one conventional milled material were tested (n = 560). Dimensions for each specimen measured 10 × 10 mm and were categorized by thickness (1 and 2 mm). AM materials were additively manufactured (3D-printed) at three orientations: 0°, 45° and 90°. Specimens were cemented with four shades of dual-cure cement: light, neutral, warm, and translucent. Color change (ΔE) and translucency parameter (TP) measurements were calculated utilizing a spectrophotometer, VITA EasyShade V. Data was analyzed with a two- way ANOVA and Tukey's post hoc tests.

Results: Neutral cement shade exhibited the lowest ΔE overall (2.30 ± 0.43). Translucent cement shade exhibited the least color difference between materials. Milled materials generally exhibited higher ΔE (5.57 ± 0.26-7.17 ± 0.33) than AM materials. Material thickness significantly affected the ΔE across all shades of cement (p < 0.05). 45° print orientation for 2 mm thick specimens exhibited the greatest clinically acceptable ΔE.

Conclusion: Cement shade may cause clinically unacceptable color changes based on material choice and 3D-printing parameters. Clinicians providing permanent AM crowns must consider the impact of cement shade and printing parameters on aesthetic outcomes.